Synth-DIY Yahoo! Groups Archives

Thread

Yamaha SY77 faulty

2013-02-15 by Royce

The unit arrived with missing screws in the case. 
Always a bad sign.

The service manual, kindly given to me (also the one on the web), is only 71 pages and really only goes through the tests.

My DX7 and TQ5 service manual are much more detailed.
Were these synths just 'swap the board" type devices?

Anyway the test stops at the self test with a message "* M3 IRQ CHECK ERROR. TEST ABORTED *" and you can't go on to the other tests.
The service manual only say "If Test B" the M3 test " is NG" no good "then the error may be related to one of the M3 IC's IRQ levels"
What does that mean??

The 2 M3 chips YM7119 are on the DM2 board have something to do with the Wave ROMs.
Is this test trying to read all the Wave ROMs and failing?
Is the CPU just timing out because the M3 isn't returning soon enough?
It's the interupt request part I don't get.

Anyone with any more info about this chip?
Anyone had this problem and managed to get past the IRQ test ?

I can get a few weird notes out but it sounds like misaddressing of the Wave ROMs and locks up fairly quickly. 

Thanks for the help
Royce

Re: [vintagesynthrepair] Recapping

2013-02-16 by Daniel Forró

As I'm in project of recapping my older devices, I'd like to ask all  
of you more experienced gurus here your opinion:

1. I started with changing electrolytic capacitors in PSU. Do you  
think it would be good to change all electrolytic capacitors in the  
machine (on digital and analog boards)? I want to use the opportunity  
of opening the machine and to avoid possible problems in near future...

2. Is it necessary to change also all bipolar, tantalum, ceramic,  
polyester... capacitors? Do they also deteriorate in time?

3. Is there some age of the device from which would be good to change  
capacitors? 15 - 20 - 25 - 30 and more years?

4. When changing old capacitors with nowadays non-existing values,  of  
course I must follow voltage or use higher value. Concerning capacity  
value should I use the nearest higher value, too? Modern capacitors  
are usually smaller than old ones, so size is not critical. I'm just  
afraid if in certain kind of circuits higher value couldn't be some  
problem...

5. Do you have eventually any other tips & tricks for maintenance of  
older machines? Of course I do cleaning, reseating IC's in sockets,  
cleaning and reseating all connectors, cleaning keyboards... I will  
also change displays in about 10 of my machines for modern LED  
backlighted types. I disassemble keyboards, clean them, lubricate if  
necessary, change key bushings... If necessary, I change  
microswitches... And I'd like to upgrade OS EPROM's in some of my  
instruments.

6. I have also two old Hammond organ (CV model from 1945 and M3 from  
1960). Do you think I should change capacitors (or even more  
components) in preamplifier (CV), amplifier (M3), tonewheel generators  
and vibrato lines? There are specialized firms offering sets of  
capacitors or other components for old Hammond organ.

I will add that all my old machines work well, and I know there's an  
old wisdom "don't touch it if it works", but... What's your opinion? I  
want to change capacitors because I'm nervous that old machines can  
have problems. But is it REALLY necessary to change it when machine  
works well?

Thanks for any answer.

Daniel Forro

RE: [vintagesynthrepair] Recapping

2013-02-16 by Brian

Hi Daniel

You only need to change electrolytic and tantalum caps, either when they are old 15 years plus, or when you can see a ring of sediment around the end cap of the positive terminal. This applies to the whole circuit, not just the PSU.

Certain makes of paper caps are also vulnerable to aging, this can be seen by a slight crack appearing in the outer case. These should also be changed.

Yes always use a higher voltage not lower. With regard to capacitance value, this depends on the specific use in the circuit. If this is a timing device then the value is important and should be matched. To match a specific value use a series parallel combination, but you will need the mathematics for this remembering that for capacitors you use the inverse of the rules you would use for resistors. If you need the maths try Googling. If all else fails I\u2019ll do you a master-class! If the use is in decoupling then higher values can be used OK.

So what other components age? Resistors do, especially old one known as carbon composition. The only answer here is to accurately measure the value and if more than 10% different from the stated value then change it for a modern item. Old VOX amps are prone to this, on a recent overhaul I changed something approaching 35 resistors all had changed value by a lot!

Regards

Brian G3OYU

From: vintagesynthrepair@yahoogroups.com [mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of Daniel Forró
Sent: 16 February 2013 9:00
To: vintagesynthrepair@yahoogroups.com
Subject: Re: [vintagesynthrepair] Recapping

As I'm in project of recapping my older devices, I'd like to ask all
of you more experienced gurus here your opinion:

1. I started with changing electrolytic capacitors in PSU. Do you
think it would be good to change all electrolytic capacitors in the
machine (on digital and analog boards)? I want to use the opportunity
of opening the machine and to avoid possible problems in near future...

2. Is it necessary to change also all bipolar, tantalum, ceramic,
polyester... capacitors? Do they also deteriorate in time?

3. Is there some age of the device from which would be good to change
capacitors? 15 - 20 - 25 - 30 and more years?

4. When changing old capacitors with nowadays non-existing values, of
course I must follow voltage or use higher value. Concerning capacity
value should I use the nearest higher value, too? Modern capacitors
are usually smaller than old ones, so size is not critical. I'm just
afraid if in certain kind of circuits higher value couldn't be some
problem...

5. Do you have eventually any other tips & tricks for maintenance of
older machines? Of course I do cleaning, reseating IC's in sockets,
cleaning and reseating all connectors, cleaning keyboards... I will
also change displays in about 10 of my machines for modern LED
backlighted types. I disassemble keyboards, clean them, lubricate if
necessary, change key bushings... If necessary, I change
microswitches... And I'd like to upgrade OS EPROM's in some of my
instruments.

6. I have also two old Hammond organ (CV model from 1945 and M3 from
1960). Do you think I should change capacitors (or even more
components) in preamplifier (CV), amplifier (M3), tonewheel generators
and vibrato lines? There are specialized firms offering sets of
capacitors or other components for old Hammond organ.

I will add that all my old machines work well, and I know there's an
old wisdom "don't touch it if it works", but... What's your opinion? I
want to change capacitors because I'm nervous that old machines can
have problems. But is it REALLY necessary to change it when machine
works well?

Thanks for any answer.

Daniel Forro

Re: [vintagesynthrepair] Recapping

2013-02-16 by Daniel Forró

Hi, Brian,

thanks for your answer, exactly this is kind of information I need. You know, I'm only musician and to some degree linguist, electronics and repairs are just my biggest hobby - but I think I was successful in all repairs I did in the past despite the lack of theoretical knowledge. But as much as my time allows I want to learn more theory, and try always to find some info on internet, which is sometimes time consuming. So I'm really grateful for advice from professionals like you.

All the best!

Daniel Forro

On 16 Feb, 2013, at 6:50 PM, Brian wrote:

Hi Daniel
You only need to change electrolytic and tantalum caps, either when they are old 15 years plus, or when you can see a ring of sediment around the end cap of the positive terminal. This applies to the whole circuit, not just the PSU.
Certain makes of paper caps are also vulnerable to aging, this can be seen by a slight crack appearing in the outer case. These should also be changed.
Yes always use a higher voltage not lower. With regard to capacitance value, this depends on the specific use in the circuit. If this is a timing device then the value is important and should be matched. To match a specific value use a series parallel combination, but you will need the mathematics for this remembering that for capacitors you use the inverse of the rules you would use for resistors. If you need the maths try Googling. If all else fails I’ll do you a master-class! If the use is in decoupling then higher values can be used OK.
So what other components age? Resistors do, especially old one known as carbon composition. The only answer here is to accurately measure the value and if more than 10% different from the stated value then change it for a modern item. Old VOX amps are prone to this, on a recent overhaul I changed something approaching 35 resistors all had changed value by a lot!
Regards
Brian G3OYU

Re: Yamaha SY77 faulty

2013-02-16 by Royce

Any experienced Yamaha techs out there?

The story so far...
I have reseated all of the EPROMs and CPU and all the cable connects.
No leaking Li battery so no board corrosion.

Looking at the DM2 board the supply is 5V02 with digital ground and 12V1 and -12V2 with analog ground and a line marked MTAG at 14V going to what looks like a comparator cct outputting a MUTE signal that turns the audio output off, probably used at power on and off.
There is a 5V and -5V pair of regs (off the +12 and -12V ) on the analog board buried underneath that I haven't checked.

Only caps on the DM2 board are PS decoupling electros and decoupling ceramics for the chips and a couple of ceramics for the crystal clock.

On the M3 chips there is a CLKMEL and a CLK3 pin.
The CLK3 is grounded and CLKMEL looks like an FX clock.
A CRO on this and it works on and off during boot then goes off until a note is played. So I guess the clock oscillator for the M3s are working. I've no idea about timing though.

The M3 IRQ is open collector and the pullup resistors all look good.
Like the CLKMEL the IRQ line oscillates in bursts which go on and off during boot and when a key is pressed post boot there is a constant stream at a varying frequency.

Anyone know what the IRQ error message in the test B means???

Thanks for the help. I could be a bit out of my depth here.

Any pointers would be gratefully received.

All the best
Royce 

--- In vintagesynthrepair@yahoogroups.com, "Royce" <rpcfender@...> wrote:

Show quoted textHide quoted text

>
> The unit arrived with missing screws in the case. 
> Always a bad sign.
> 
> The service manual, kindly given to me (also the one on the web), is only 71 pages and really only goes through the tests.
> 
> My DX7 and TQ5 service manual are much more detailed.
> Were these synths just 'swap the board" type devices?
> 
> Anyway the test stops at the self test with a message "* M3 IRQ CHECK ERROR. TEST ABORTED *" and you can't go on to the other tests.
> The service manual only say "If Test B" the M3 test " is NG" no good "then the error may be related to one of the M3 IC's IRQ levels"
> What does that mean??
> 
> The 2 M3 chips YM7119 are on the DM2 board have something to do with the Wave ROMs.
> Is this test trying to read all the Wave ROMs and failing?
> Is the CPU just timing out because the M3 isn't returning soon enough?
> It's the interupt request part I don't get.
> 
> Anyone with any more info about this chip?
> Anyone had this problem and managed to get past the IRQ test ?
> 
> I can get a few weird notes out but it sounds like misaddressing of the Wave ROMs and locks up fairly quickly. 
> 
> Thanks for the help
> Royce
>

RE: [vintagesynthrepair] Re: Yamaha SY77 faulty

2013-02-16 by Lorne Hammond

Not experienced but I would say that those sound like normal voltagesl.  So
I'd believe the test and look at the physical circuit at those ICs.  If
socketed I would carefully photograph the circuit, static free pull the ICs
out of any sockets and desolder the sockets and put in new ones.  I would
gently reheat solder connections to resistors and caps immediately around
the ICs and replace any transistor.  I am thinking cold solder or
microfracture breaks, failed component but usually not any ceramic caps or
resistors.  I never trust old IC sockets.  I would look closely at any logic
ICs as well.  If your clock is okay and shows up at the chip's IN pin then
its not that.  Its iss rare that the wavetable samples are messed up, unless
someone has had a magnet around.  I'd definitely change the decoupling
electrolytics.   Lorne in Canada

From: vintagesynthrepair@yahoogroups.com
[mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of Royce
Sent: Saturday, February 16, 2013 6:08 AM
To: vintagesynthrepair@yahoogroups.com
Subject: [vintagesynthrepair] Re: Yamaha SY77 faulty

Any experienced Yamaha techs out there?

The story so far...
I have reseated all of the EPROMs and CPU and all the cable connects.
No leaking Li battery so no board corrosion.

Looking at the DM2 board the supply is 5V02 with digital ground and 12V1 and
-12V2 with analog ground and a line marked MTAG at 14V going to what looks
like a comparator cct outputting a MUTE signal that turns the audio output
off, probably used at power on and off.
There is a 5V and -5V pair of regs (off the +12 and -12V ) on the analog
board buried underneath that I haven't checked.

Only caps on the DM2 board are PS decoupling electros and decoupling
ceramics for the chips and a couple of ceramics for the crystal clock.

On the M3 chips there is a CLKMEL and a CLK3 pin.
The CLK3 is grounded and CLKMEL looks like an FX clock.
A CRO on this and it works on and off during boot then goes off until a note
is played. So I guess the clock oscillator for the M3s are working. I've no
idea about timing though.

The M3 IRQ is open collector and the pullup resistors all look good.
Like the CLKMEL the IRQ line oscillates in bursts which go on and off during
boot and when a key is pressed post boot there is a constant stream at a
varying frequency.

Anyone know what the IRQ error message in the test B means???

Thanks for the help. I could be a bit out of my depth here.

Any pointers would be gratefully received.

All the best
Royce 

--- In vintagesynthrepair@yahoogroups.com
<mailto:vintagesynthrepair%40yahoogroups.com> , "Royce" wrote:
>
> The unit arrived with missing screws in the case. 
> Always a bad sign.
> 
> The service manual, kindly given to me (also the one on the web), is only
71 pages and really only goes through the tests.
> 
> My DX7 and TQ5 service manual are much more detailed.
> Were these synths just 'swap the board" type devices?
> 
> Anyway the test stops at the self test with a message "* M3 IRQ CHECK
ERROR. TEST ABORTED *" and you can't go on to the other tests.
> The service manual only say "If Test B" the M3 test " is NG" no good "then
the error may be related to one of the M3 IC's IRQ levels"
> What does that mean??
> 
> The 2 M3 chips YM7119 are on the DM2 board have something to do with the
Wave ROMs.
> Is this test trying to read all the Wave ROMs and failing?
> Is the CPU just timing out because the M3 isn't returning soon enough?
> It's the interupt request part I don't get.
> 
> Anyone with any more info about this chip?
> Anyone had this problem and managed to get past the IRQ test ?
> 
> I can get a few weird notes out but it sounds like misaddressing of the
Wave ROMs and locks up fairly quickly.

Show quoted textHide quoted text

> 
> Thanks for the help
> Royce
>

RE: [vintagesynthrepair] Recapping

2013-02-16 by Lorne Hammond

Tips:

A digital camera is a good friend to a set of schematics. I like to go on macro and shoot what I am about to work on. If you need to stop and order parts and come back weeks later

you may learn that some connectors can go on either way (ARPS for example) or you might forget which side was the + on that cap and the board is not marked.

Generally if you are changing tants or polarized capacitors on a board, do it one value at a time, so you do not accidentally put one in reversed. In a complex rebuild that can cause a lot of head scratching hours later when you boot up.

If there are sockets, then why not change them as well. They can be a mechanical or cold solder weak point. Some techs hate them. But, after your done test every pin for continuity before you reseat the ICs. Look at the pics as well before reseating because every now and then a designer is inconsistent about IC orientation (truer for older circuits, why I don\u2019;t know).

I have at least once accidentally put a socket in reversed when distracted. Then I used the socket notch to put the chip back \u201ccorrectly,\u201d surprise it didn\u2019t run. User error. Didn\u2019t kill the IC though.

Be a turtle with a camera not a hare with a desoldering sucker.

desolder plungers are great.

Too much desolder heat will double your original damage.

Cheers Lorne in canada

From: vintagesynthrepair@yahoogroups.com [mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of Daniel Forró
Sent: Saturday, February 16, 2013 1:00 AM
To: vintagesynthrepair@yahoogroups.com
Subject: Re: [vintagesynthrepair] Recapping

Re: [vintagesynthrepair] Recapping

2013-02-16 by Daniel Forró

Thanks a lot, Lorne, these are great tips.

Daniel F

On 17 Feb, 2013, at 1:44 AM, Lorne Hammond wrote:

Tips:

A digital camera is a good friend to a set of schematics. I like to go on macro and shoot what I am about to work on. If you need to stop and order parts and come back weeks later
you may learn that some connectors can go on either way (ARPS for example) or you might forget which side was the + on that cap and the board is not marked.

Generally if you are changing tants or polarized capacitors on a board, do it one value at a time, so you do not accidentally put one in reversed. In a complex rebuild that can cause a lot of head scratching hours later when you boot up.

If there are sockets, then why not change them as well. They can be a mechanical or cold solder weak point. Some techs hate them. But, after your done test every pin for continuity before you reseat the ICs. Look at the pics as well before reseating because every now and then a designer is inconsistent about IC orientation (truer for older circuits, why I don’t know).

I have at least once accidentally put a socket in reversed when distracted. Then I used the socket notch to put the chip back “correctly,” surprise it didn’t run. User error. ; Didn’t kill the IC though.

Be a turtle with a camera not a hare with a desoldering sucker.

desolder plungers are great.

Too much desolder heat will double your original damage.

Cheers Lorne in canada
From: vintagesynthrepair@yahoogroups.com [mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of Daniel Forró
Sent: Saturday, February 16, 2013 1:00 AM
To: vintagesynthrepair@yahoogroups.com
Subject: Re: [vintagesynthrepair] Recapping

As I'm in project of recapping my older devices, I'd like to ask all
of you more experienced gurus here your opinion:

1. I started with changing electrolytic capacitors in PSU. Do you
think it would be good to change all electrolytic capacitors in the
machine (on digital and analog boards)? I want to use the opportunity
of opening the machine and to avoid possible problems in near future...

2. Is it necessary to change also all bipolar, tantalum, ceramic,
polyester... capacitors? Do they also deteriorate in time?

3. Is there some age of the device from which would be good to change
capacitors? 15 - 20 - 25 - 30 and more years?

4. When changing old capacitors with nowadays non-existing values, of
course I must follow voltage or use higher value. Concerning capacity
value should I use the nearest higher value, too? Modern capacitors
are usually smaller than old ones, so size is not critical. I'm just
afraid if in certain kind of circuits higher value couldn't be some
problem...

5. Do you have eventually any other tips & tricks for maintenance of
older machines? Of course I do cleaning, reseating IC's in sockets,
cleaning and reseating all connectors, cleaning keyboards... I will
also change displays in about 10 of my machines for modern LED
backlighted types. I disassemble keyboards, clean them, lubricate if
necessary, change key bushings... If necessary, I change
microswitches... And I'd like to upgrade OS EPROM's in some of my
instruments.

6. I have also two old Hammond organ (CV model from 1945 and M3 from
1960). Do you think I should change capacitors (or even more
components) in preamplifier (CV), amplifier (M3), tonewheel generators
and vibrato lines? There are specialized firms offering sets of
capacitors or other components for old Hammond organ.

I will add that all my old machines work well, and I know there's an
old wisdom "don't touch it if it works", but... What's your opinion? I
want to change capacitors because I'm nervous that old machines can
have problems. But is it REALLY necessary to change it when machine
works well?

Thanks for any answer.

Daniel Forro

Re: Yamaha SY77 faulty

2013-02-17 by Royce

Thanks Lorne


> I'd believe the test and look at the physical circuit at those ICs.  If
> socketed I would carefully photograph the circuit, static free pull the ICs
> out of any sockets and desolder the sockets and put in new ones.  I would
> gently reheat solder connections to resistors and caps immediately around
> the ICs and replace any transistor.

The M3s are soldered surface mount. Cleaned the tracks
The IRQs seem perfectly good (with a better CRO probe)

>I am thinking cold solder or
> microfracture breaks, failed component but usually not any ceramic caps or
> resistors.  I never trust old IC sockets.  I would look closely at any logic
> ICs as well.  If your clock is okay and shows up at the chip's IN pin then
> its not that.  Its iss rare that the wavetable samples are messed up, unless
> someone has had a magnet around.  I'd definitely change the decoupling
> electrolytics.   Lorne in Canada

Re-soldered the resistors but no luck.

Thanks Lorne

Show quoted textHide quoted text

> 
>  
> 
> From: vintagesynthrepair@yahoogroups.com
> [mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of Royce
> Sent: Saturday, February 16, 2013 6:08 AM
> To: vintagesynthrepair@yahoogroups.com
> Subject: [vintagesynthrepair] Re: Yamaha SY77 faulty
> 
>  
> 
>   
> 
> Any experienced Yamaha techs out there?
> 
> The story so far...
> I have reseated all of the EPROMs and CPU and all the cable connects.
> No leaking Li battery so no board corrosion.
> 
> Looking at the DM2 board the supply is 5V02 with digital ground and 12V1 and
> -12V2 with analog ground and a line marked MTAG at 14V going to what looks
> like a comparator cct outputting a MUTE signal that turns the audio output
> off, probably used at power on and off.
> There is a 5V and -5V pair of regs (off the +12 and -12V ) on the analog
> board buried underneath that I haven't checked.
> 
> Only caps on the DM2 board are PS decoupling electros and decoupling
> ceramics for the chips and a couple of ceramics for the crystal clock.
> 
> On the M3 chips there is a CLKMEL and a CLK3 pin.
> The CLK3 is grounded and CLKMEL looks like an FX clock.
> A CRO on this and it works on and off during boot then goes off until a note
> is played. So I guess the clock oscillator for the M3s are working. I've no
> idea about timing though.
> 
> The M3 IRQ is open collector and the pullup resistors all look good.
> Like the CLKMEL the IRQ line oscillates in bursts which go on and off during
> boot and when a key is pressed post boot there is a constant stream at a
> varying frequency.
> 
> Anyone know what the IRQ error message in the test B means???
> 
> Thanks for the help. I could be a bit out of my depth here.
> 
> Any pointers would be gratefully received.
> 
> All the best
> Royce 
> 
> --- In vintagesynthrepair@yahoogroups.com
> <mailto:vintagesynthrepair%40yahoogroups.com> , "Royce" wrote:
> >
> > The unit arrived with missing screws in the case. 
> > Always a bad sign.
> > 
> > The service manual, kindly given to me (also the one on the web), is only
> 71 pages and really only goes through the tests.
> > 
> > My DX7 and TQ5 service manual are much more detailed.
> > Were these synths just 'swap the board" type devices?
> > 
> > Anyway the test stops at the self test with a message "* M3 IRQ CHECK
> ERROR. TEST ABORTED *" and you can't go on to the other tests.
> > The service manual only say "If Test B" the M3 test " is NG" no good "then
> the error may be related to one of the M3 IC's IRQ levels"
> > What does that mean??
> > 
> > The 2 M3 chips YM7119 are on the DM2 board have something to do with the
> Wave ROMs.
> > Is this test trying to read all the Wave ROMs and failing?
> > Is the CPU just timing out because the M3 isn't returning soon enough?
> > It's the interupt request part I don't get.
> > 
> > Anyone with any more info about this chip?
> > Anyone had this problem and managed to get past the IRQ test ?
> > 
> > I can get a few weird notes out but it sounds like misaddressing of the
> Wave ROMs and locks up fairly quickly. 
> > 
> > Thanks for the help
> > Royce
> >
>

Re: Yamaha SY77 faulty

2013-02-21 by Royce

More info...
When playing the synth the multiples of the 13th and 14th notes fail to sound or sound strange. 

My first thought would be the SRAM, but the SRAM is tested and passes the first test (TEST A).

Any ideas?


--- In vintagesynthrepair@yahoogroups.com, "Royce" <rpcfender@...> wrote:

Show quoted textHide quoted text

>
> Thanks Lorne
> 
> 
> > I'd believe the test and look at the physical circuit at those ICs.  If
> > socketed I would carefully photograph the circuit, static free pull the ICs
> > out of any sockets and desolder the sockets and put in new ones.  I would
> > gently reheat solder connections to resistors and caps immediately around
> > the ICs and replace any transistor.
> 
> The M3s are soldered surface mount. Cleaned the tracks
> The IRQs seem perfectly good (with a better CRO probe)
> 
> >I am thinking cold solder or
> > microfracture breaks, failed component but usually not any ceramic caps or
> > resistors.  I never trust old IC sockets.  I would look closely at any logic
> > ICs as well.  If your clock is okay and shows up at the chip's IN pin then
> > its not that.  Its iss rare that the wavetable samples are messed up, unless
> > someone has had a magnet around.  I'd definitely change the decoupling
> > electrolytics.   Lorne in Canada
> 
> Re-soldered the resistors but no luck.
> 
> Thanks Lorne
> > 
> >  
> > 
> > From: vintagesynthrepair@yahoogroups.com
> > [mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of Royce
> > Sent: Saturday, February 16, 2013 6:08 AM
> > To: vintagesynthrepair@yahoogroups.com
> > Subject: [vintagesynthrepair] Re: Yamaha SY77 faulty
> > 
> >  
> > 
> >   
> > 
> > Any experienced Yamaha techs out there?
> > 
> > The story so far...
> > I have reseated all of the EPROMs and CPU and all the cable connects.
> > No leaking Li battery so no board corrosion.
> > 
> > Looking at the DM2 board the supply is 5V02 with digital ground and 12V1 and
> > -12V2 with analog ground and a line marked MTAG at 14V going to what looks
> > like a comparator cct outputting a MUTE signal that turns the audio output
> > off, probably used at power on and off.
> > There is a 5V and -5V pair of regs (off the +12 and -12V ) on the analog
> > board buried underneath that I haven't checked.
> > 
> > Only caps on the DM2 board are PS decoupling electros and decoupling
> > ceramics for the chips and a couple of ceramics for the crystal clock.
> > 
> > On the M3 chips there is a CLKMEL and a CLK3 pin.
> > The CLK3 is grounded and CLKMEL looks like an FX clock.
> > A CRO on this and it works on and off during boot then goes off until a note
> > is played. So I guess the clock oscillator for the M3s are working. I've no
> > idea about timing though.
> > 
> > The M3 IRQ is open collector and the pullup resistors all look good.
> > Like the CLKMEL the IRQ line oscillates in bursts which go on and off during
> > boot and when a key is pressed post boot there is a constant stream at a
> > varying frequency.
> > 
> > Anyone know what the IRQ error message in the test B means???
> > 
> > Thanks for the help. I could be a bit out of my depth here.
> > 
> > Any pointers would be gratefully received.
> > 
> > All the best
> > Royce 
> > 
> > --- In vintagesynthrepair@yahoogroups.com
> > <mailto:vintagesynthrepair%40yahoogroups.com> , "Royce" wrote:
> > >
> > > The unit arrived with missing screws in the case. 
> > > Always a bad sign.
> > > 
> > > The service manual, kindly given to me (also the one on the web), is only
> > 71 pages and really only goes through the tests.
> > > 
> > > My DX7 and TQ5 service manual are much more detailed.
> > > Were these synths just 'swap the board" type devices?
> > > 
> > > Anyway the test stops at the self test with a message "* M3 IRQ CHECK
> > ERROR. TEST ABORTED *" and you can't go on to the other tests.
> > > The service manual only say "If Test B" the M3 test " is NG" no good "then
> > the error may be related to one of the M3 IC's IRQ levels"
> > > What does that mean??
> > > 
> > > The 2 M3 chips YM7119 are on the DM2 board have something to do with the
> > Wave ROMs.
> > > Is this test trying to read all the Wave ROMs and failing?
> > > Is the CPU just timing out because the M3 isn't returning soon enough?
> > > It's the interupt request part I don't get.
> > > 
> > > Anyone with any more info about this chip?
> > > Anyone had this problem and managed to get past the IRQ test ?
> > > 
> > > I can get a few weird notes out but it sounds like misaddressing of the
> > Wave ROMs and locks up fairly quickly. 
> > > 
> > > Thanks for the help
> > > Royce
> > >
> >
>

Re: Yamaha SY77 faulty

2013-02-23 by Royce

Well I now fairly certain that it is the M3PCM (YM7115) chip.
I have no desire to try and replace the chip, but I would like to get a new DM2 board (XG525). This is the voice board.

Yes, I can hear you laugh, but perhaps someone knows where there might be one sitting on a shelf.

Perhaps there is another damaged SY77 with a good DM2 board?
Does anyone know if the TG77 used the same board?

Thanks for the help
Royce

>

--- In vintagesynthrepair@yahoogroups.com, "Royce" <rpcfender@...> wrote:

Show quoted textHide quoted text

>
> More info...
> When playing the synth the multiples of the 13th and 14th notes fail to sound or sound strange. 
> 
> My first thought would be the SRAM, but the SRAM is tested and passes the first test (TEST A).
> 
> Any ideas?
> 
> 
> --- In vintagesynthrepair@yahoogroups.com, "Royce" <rpcfender@> wrote:
> >
> > Thanks Lorne
> > 
> > 
> > > I'd believe the test and look at the physical circuit at those ICs.  If
> > > socketed I would carefully photograph the circuit, static free pull the ICs
> > > out of any sockets and desolder the sockets and put in new ones.  I would
> > > gently reheat solder connections to resistors and caps immediately around
> > > the ICs and replace any transistor.
> > 
> > The M3s are soldered surface mount. Cleaned the tracks
> > The IRQs seem perfectly good (with a better CRO probe)
> > 
> > >I am thinking cold solder or
> > > microfracture breaks, failed component but usually not any ceramic caps or
> > > resistors.  I never trust old IC sockets.  I would look closely at any logic
> > > ICs as well.  If your clock is okay and shows up at the chip's IN pin then
> > > its not that.  Its iss rare that the wavetable samples are messed up, unless
> > > someone has had a magnet around.  I'd definitely change the decoupling
> > > electrolytics.   Lorne in Canada
> > 
> > Re-soldered the resistors but no luck.
> > 
> > Thanks Lorne
> > > 
> > >  
> > > 
> > > From: vintagesynthrepair@yahoogroups.com
> > > [mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of Royce
> > > Sent: Saturday, February 16, 2013 6:08 AM
> > > To: vintagesynthrepair@yahoogroups.com
> > > Subject: [vintagesynthrepair] Re: Yamaha SY77 faulty
> > > 
> > >  
> > > 
> > >   
> > > 
> > > Any experienced Yamaha techs out there?
> > > 
> > > The story so far...
> > > I have reseated all of the EPROMs and CPU and all the cable connects.
> > > No leaking Li battery so no board corrosion.
> > > 
> > > Looking at the DM2 board the supply is 5V02 with digital ground and 12V1 and
> > > -12V2 with analog ground and a line marked MTAG at 14V going to what looks
> > > like a comparator cct outputting a MUTE signal that turns the audio output
> > > off, probably used at power on and off.
> > > There is a 5V and -5V pair of regs (off the +12 and -12V ) on the analog
> > > board buried underneath that I haven't checked.
> > > 
> > > Only caps on the DM2 board are PS decoupling electros and decoupling
> > > ceramics for the chips and a couple of ceramics for the crystal clock.
> > > 
> > > On the M3 chips there is a CLKMEL and a CLK3 pin.
> > > The CLK3 is grounded and CLKMEL looks like an FX clock.
> > > A CRO on this and it works on and off during boot then goes off until a note
> > > is played. So I guess the clock oscillator for the M3s are working. I've no
> > > idea about timing though.
> > > 
> > > The M3 IRQ is open collector and the pullup resistors all look good.
> > > Like the CLKMEL the IRQ line oscillates in bursts which go on and off during
> > > boot and when a key is pressed post boot there is a constant stream at a
> > > varying frequency.
> > > 
> > > Anyone know what the IRQ error message in the test B means???
> > > 
> > > Thanks for the help. I could be a bit out of my depth here.
> > > 
> > > Any pointers would be gratefully received.
> > > 
> > > All the best
> > > Royce 
> > > 
> > > --- In vintagesynthrepair@yahoogroups.com
> > > <mailto:vintagesynthrepair%40yahoogroups.com> , "Royce" wrote:
> > > >
> > > > The unit arrived with missing screws in the case. 
> > > > Always a bad sign.
> > > > 
> > > > The service manual, kindly given to me (also the one on the web), is only
> > > 71 pages and really only goes through the tests.
> > > > 
> > > > My DX7 and TQ5 service manual are much more detailed.
> > > > Were these synths just 'swap the board" type devices?
> > > > 
> > > > Anyway the test stops at the self test with a message "* M3 IRQ CHECK
> > > ERROR. TEST ABORTED *" and you can't go on to the other tests.
> > > > The service manual only say "If Test B" the M3 test " is NG" no good "then
> > > the error may be related to one of the M3 IC's IRQ levels"
> > > > What does that mean??
> > > > 
> > > > The 2 M3 chips YM7119 are on the DM2 board have something to do with the
> > > Wave ROMs.
> > > > Is this test trying to read all the Wave ROMs and failing?
> > > > Is the CPU just timing out because the M3 isn't returning soon enough?
> > > > It's the interupt request part I don't get.
> > > > 
> > > > Anyone with any more info about this chip?
> > > > Anyone had this problem and managed to get past the IRQ test ?
> > > > 
> > > > I can get a few weird notes out but it sounds like misaddressing of the
> > > Wave ROMs and locks up fairly quickly. 
> > > > 
> > > > Thanks for the help
> > > > Royce
> > > >
> > >
> >
>

Re: [vintagesynthrepair] Recapping

2013-04-08 by 65 Lotus

Internally tanatlums look like a sponge where their charging surface area is exposed in 3-dimensions, whereas electrolytics are a couple of wound, flat pieces of foil.

Due to their inherent structure, tanatalums charge very quickly as the 3-D surface gets easily flooded with electrons, whereas for electrolytics, the electrons have to spread around the plate to be saturated. That takes time.

So, tantalums are very good for high frequency cap duties, like on the crystal (clock) circuits. For power rails, electrolytics are fine of course, but for anything that's a high frequency circuit, I'd stick with a tantalum if was spec'ed that way to begin with.

Tantalums are very unfogiving of overvoltage which is what usually kills them. Once they're saturated, the slightest voltage over their rating will do them in, where they melt into a short. They work great when used properly in a circuit where the probability that they'll ever see a spike is nil. Replacing a tant with one with a larger rating will slow down the saturation time, so again, I'd just replace it with the original rating component. I like the Vishay brand which is what we use in the aviation industry where I work.

I'm no expert (I'm a mechanical engineer however), but I spent a few hours researching the ins-and-outs of tants one day right before I did a full recap on my OB-Xa. If it was tantalum, it stayed that way.

Scott in Ohio

Show quoted textHide quoted text

----- Original Message -----

From: Daniel Forró

To: vintagesynthrepair@yahoogroups.com

Sent: Monday, April 08, 2013 11:01 AM

Subject: Re: [vintagesynthrepair] Recapping

Thanks for your explanation and the link. So can I take it as a rule of thumb and change all tantalum (in PSU, logic circuits or audio circuits) for low ESR electrolytic? Or is there some case where to change just old tantalum for new one? Could for example using of tantalum rated for higher voltage serve as a sort of better protection against possible fail?

I had this fire problem with two ceramic disk caps in the PSU of one old Russian instrument which was not in use for few years. Fortunately I could see the fire, it started immediately after switching on, so I just switched off. It was enough to change those caps and instrument is OK, but I will do complete recapping.

Daniel Forro

On 8 Apr, 2013, at 11:32 PM, Alexis V. Rogers wrote:

Tantalums were used due to size and lower ESR. You can get low ESR electrolytics these days. The problem with tantalums is that they close (short) when they fail. When used in a power supply situation, I've seen tantalums burst into flame and end up looking like burnt marshmallows.

I've never added capacitors to the IC power lines unless I was replacing with a different IC whose datasheet called for it.

And, I get my can caps through http://www.tubesandmore.com/.

Re: [vintagesynthrepair] Recapping

2013-04-09 by Daniel Forró

Thanks for your perfect explanation!

Daniel Forro

Show quoted textHide quoted text

On 9 Apr, 2013, at 2:03 AM, 65 Lotus wrote:

>
>
> Internally tanatlums look like a sponge where their charging surface  
> area is exposed in 3-dimensions, whereas electrolytics are a couple  
> of wound, flat pieces of foil.
>
> Due to their inherent structure, tanatalums charge very quickly as  
> the 3-D surface gets easily flooded with electrons, whereas for  
> electrolytics, the electrons have to spread around the plate to be  
> saturated. That takes time.
>
> So, tantalums are very good for high frequency cap duties, like on  
> the crystal (clock) circuits. For power rails, electrolytics are  
> fine of course, but for anything that's a high frequency circuit,  
> I'd stick with a tantalum if was spec'ed that way to begin with.
>
> Tantalums are very unfogiving of overvoltage which is what usually  
> kills them. Once they're saturated, the slightest voltage over their  
> rating will do them in, where they melt into a short. They work  
> great when used properly in a circuit where the probability that  
> they'll ever see a spike is nil. Replacing a tant with one with a  
> larger rating will slow down the saturation time, so again, I'd just  
> replace it with the original rating component. I like the Vishay  
> brand which is what we use in the aviation industry where I work.
>
> I'm no expert (I'm a mechanical engineer however), but I spent a few  
> hours researching the ins-and-outs of tants one day right before I  
> did a full recap on my OB-Xa. If it was tantalum, it stayed that way.
>
> Scott in Ohio
>

Re: Recapping

2013-04-10 by hughvartanian

The old electrical engineers vote, in agreement with Scott from Ohio, to respect the original design intent and replace the tantalum caps with tantalum caps.  In the old days of the 1960's and 70's there were issues with tantalum parts shorting out and blowing up and stuff.  Pretty sure these issues have been worked out OK.  I use many of them for supply decoupling by the thousands in lab equipment I have designed, as well as when re-capping old oscilloscopes/test equipment, and would do so as well in ones I run into inside electronic musical instruments.  All this said, I can't say that I have done a detailed comparison of ESR vs. frequency between low-ESR aluminum parts and the tantalum caps.

Couple of other comments to other posts: Multi-section can capacitors are being made brand new, and are generally available, as previously noted, at tubesandmore.com

Fine to go up in capacitance value, and voltage.  However, with voltage it isn't generally a good idea to go way up in voltage.  Like to use a 450V section when the original is a 50V part.  If you can't find the exact match, put in a discrete part in the event your can has a 50V (or whatever) section.  Extra sections in the can, assuming the voltage is OK, can be paralleled with other ones.

I have found, I think when re-capping a Juno 106, that they used a lot of 16V electrolytic caps on the 15V rails.  I'm not comfortable at all with this and recommend using 25V or 35V parts instead.

Note that newer aluminum caps are usually much smaller than their vintage counterparts.  Therefore, if you want to get some economy of quantity buy, you can, for example replace all the 10uf and 22uf parts with 22uf parts (for supply decoupling, anyway).

For the best reliability, try and get 105 deg C caps instead of 85 deg parts.  Across the board (no pun intended).  Not that you should lose sleep if you can't find a particular value/voltage in 105 deg, but good to try.

Mouser and digikey are great sources for parts.  Online part searching, and ordering all work pretty well (although the printed catalog is good for browsing).

Great discussions!

Hugh




--- In vintagesynthrepair@yahoogroups.com, Daniel Forró <dan.for@...> wrote:

Show quoted textHide quoted text

>
> Thanks for your perfect explanation!
> 
> Daniel Forro
> 
> 
> On 9 Apr, 2013, at 2:03 AM, 65 Lotus wrote:
> 
> >
> >
> > Internally tanatlums look like a sponge where their charging surface  
> > area is exposed in 3-dimensions, whereas electrolytics are a couple  
> > of wound, flat pieces of foil.
> >
> > Due to their inherent structure, tanatalums charge very quickly as  
> > the 3-D surface gets easily flooded with electrons, whereas for  
> > electrolytics, the electrons have to spread around the plate to be  
> > saturated. That takes time.
> >
> > So, tantalums are very good for high frequency cap duties, like on  
> > the crystal (clock) circuits. For power rails, electrolytics are  
> > fine of course, but for anything that's a high frequency circuit,  
> > I'd stick with a tantalum if was spec'ed that way to begin with.
> >
> > Tantalums are very unfogiving of overvoltage which is what usually  
> > kills them. Once they're saturated, the slightest voltage over their  
> > rating will do them in, where they melt into a short. They work  
> > great when used properly in a circuit where the probability that  
> > they'll ever see a spike is nil. Replacing a tant with one with a  
> > larger rating will slow down the saturation time, so again, I'd just  
> > replace it with the original rating component. I like the Vishay  
> > brand which is what we use in the aviation industry where I work.
> >
> > I'm no expert (I'm a mechanical engineer however), but I spent a few  
> > hours researching the ins-and-outs of tants one day right before I  
> > did a full recap on my OB-Xa. If it was tantalum, it stayed that way.
> >
> > Scott in Ohio
> >
>

Re: [vintagesynthrepair] Re: Recapping

2013-04-10 by Richard van der Meer

Thanks Hugh

for all this great info.

regarding caps if i replace a 35V version with a 50V version (which i have laying around) would that be OK

or would it be best to stick with a 35V?

Does this have something to do with the capacitor charging curve?

regards

richard

Show quoted textHide quoted text

2013/4/10 hughvartanian <bouncev@gmail.com>

The old electrical engineers vote, in agreement with Scott from Ohio, to respect the original design intent and replace the tantalum caps with tantalum caps. In the old days of the 1960's and 70's there were issues with tantalum parts shorting out and blowing up and stuff. Pretty sure these issues have been worked out OK. I use many of them for supply decoupling by the thousands in lab equipment I have designed, as well as when re-capping old oscilloscopes/test equipment, and would do so as well in ones I run into inside electronic musical instruments. All this said, I can't say that I have done a detailed comparison of ESR vs. frequency between low-ESR aluminum parts and the tantalum caps.

Couple of other comments to other posts: Multi-section can capacitors are being made brand new, and are generally available, as previously noted, at tubesandmore.com

Fine to go up in capacitance value, and voltage. However, with voltage it isn';t generally a good idea to go way up in voltage. Like to use a 450V section when the original is a 50V part. If you can't find the exact match, put in a discrete part in the event your can has a 50V (or whatever) section. Extra sections in the can, assuming the voltage is OK, can be paralleled with other ones.

I have found, I think when re-capping a Juno 106, that they used a lot of 16V electrolytic caps on the 15V rails. I';m not comfortable at all with this and recommend using 25V or 35V parts instead.

Note that newer aluminum caps are usually much smaller than their vintage counterparts. Therefore, if you want to get some economy of quantity buy, you can, for example replace all the 10uf and 22uf parts with 22uf parts (for supply decoupling, anyway).

For the best reliability, try and get 105 deg C caps instead of 85 deg parts. Across the board (no pun intended). Not that you should lose sleep if you can't find a particular value/voltage in 105 deg, but good to try.

Mouser and digikey are great sources for parts. Online part searching, and ordering all work pretty well (although the printed catalog is good for browsing).

Great discussions!

Hugh

--- In vintagesynthrepair@yahoogroups.com, Daniel Forró >
> Thanks for your perfect explanation!
>
> Daniel Forro
>
>
> On 9 Apr, 2013, at 2:03 AM, 65 Lotus wrote:
>
> >
> >
> > Internally tanatlums look like a sponge where their charging surface
> > area is exposed in 3-dimensions, whereas electrolytics are a couple
> > of wound, flat pieces of foil.
> >
> > Due to their inherent structure, tanatalums charge very quickly as
> > the 3-D surface gets easily flooded with electrons, whereas for
> > electrolytics, the electrons have to spread around the plate to be
> > saturated. That takes time.
> >
> > So, tantalums are very good for high frequency cap duties, like on
> > the crystal (clock) circuits. For power rails, electrolytics are
> > fine of course, but for anything that's a high frequency circuit,
> > I'd stick with a tantalum if was spec'ed that way to begin with.
> >
> > Tantalums are very unfogiving of overvoltage which is what usually
> > kills them. Once they're saturated, the slightest voltage over their
> > rating will do them in, where they melt into a short. They work
> > great when used properly in a circuit where the probability that
> > they'll ever see a spike is nil. Replacing a tant with one with a
> > larger rating will slow down the saturation time, so again, I'd just
> > replace it with the original rating component. I like the Vishay
> > brand which is what we use in the aviation industry where I work.
> >;
> > I'm no expert (I'm a mechanical engineer however), but I spent a few
> > hours researching the ins-and-outs of tants one day right before I
> > did a full recap on my OB-Xa. If it was tantalum, it stayed that way.
> >
> > Scott in Ohio
> >
>

--
Met vriendelijke groet / regards

Richard van der Meer

check out my music at:

http://www.youtube.com/ricardodilago

http://soundcloud.com/ricardo-di-lago

Re: [vintagesynthrepair] Re: Recapping

2013-04-10 by Mike Kearney

For recapping tube Hammonds, old tube radios and a Forbes-design tube 
Theremin I built, I've had very good luck dealing with 
http://justradios.com/

There have some helpful tips here: http://www.justradios.com/captips.html

Regards,
Mike

Re: [vintagesynthrepair] Re: Recapping

2013-04-10 by Hugh Vartanian

Hi Richard,

A 50V cap in place of a 35V part will be just fine.

I'm not sure where I picked up the idea that it wasn't a great idea to use, for example, a 450V cap in a 25V circuit. Maybe my father; I will ask him when I see him next (86 yrs old and still teaching electrical engineering at college level!) Might be because of the ESR of the higher voltage part, something to do with its life (there was this process called re-forming an old capacitor, running it up to voltage slowly or something like that, which might lead one to believe that a capacitor wants to be run somewhere in the ballpark of its rated voltage). Anyway, this all could be a wives tale I'm telling based on the construction of parts used in earlier times.

I have a longer story to answer the questions about ESR, how and why of where different types of capacitors are used, IC decoupling capacitor types/values/construction specifically in answer to the original post, etc. At work now and no time to craft that. Probably google-able.

Hugh

Show quoted textHide quoted text

On Wed, Apr 10, 2013 at 2:05 AM, Richard van der Meer <ricardodilago@...> wrote:

Thanks Hugh
for all this great info.
regarding caps if i replace a 35V version with a 50V version (which i have laying around) would that be OK
or would it be best to stick with a 35V?

Does this have something to do with the capacitor charging curve?

regards

richard

2013/4/10 hughvartanian <bouncev@...>;

The old electrical engineers vote, in agreement with Scott from Ohio, to respect the original design intent and replace the tantalum caps with tantalum caps. In the old days of the 1960's and 70's there were issues with tantalum parts shorting out and blowing up and stuff. Pretty sure these issues have been worked out OK. I use many of them for supply decoupling by the thousands in lab equipment I have designed, as well as when re-capping old oscilloscopes/test equipment, and would do so as well in ones I run into inside electronic musical instruments. All this said, I can't say that I have done a detailed comparison of ESR vs. frequency between low-ESR aluminum parts and the tantalum caps.

Couple of other comments to other posts: Multi-section can capacitors are being made brand new, and are generally available, as previously noted, at tubesandmore.com

Fine to go up in capacitance value, and voltage. However, with voltage it isn't generally a good idea to go way up in voltage. Like to use a 450V section when the original is a 50V part. If you can't find the exact match, put in a discrete part in the event your can has a 50V (or whatever) section. Extra sections in the can, assuming the voltage is OK, can be paralleled with other ones.

I have found, I think when re-capping a Juno 106, that they used a lot of 16V electrolytic caps on the 15V rails. I'm not comfortable at all with this and recommend using 25V or 35V parts instead.

Note that newer aluminum caps are usually much smaller than their vintage counterparts. Therefore, if you want to get some economy of quantity buy, you can, for example replace all the 10uf and 22uf parts with 22uf parts (for supply decoupling, anyway).

For the best reliability, try and get 105 deg C caps instead of 85 deg parts. Across the board (no pun intended). Not that you should lose sleep if you can't find a particular value/voltage in 105 deg, but good to try.

Mouser and digikey are great sources for parts. Online part searching, and ordering all work pretty well (although the printed catalog is good for browsing).

Great discussions!

Hugh

--- In vintagesynthrepair@yahoogroups.com, Daniel Forró <;dan.for@...> wrote:
>
> Thanks for your perfect explanation!
>
> Daniel Forro
>
>
> On 9 Apr, 2013, at 2:03 AM, 65 Lotus wrote:
>
> >
> >
> > Internally tanatlums look like a sponge where their charging surface
> > area is exposed in 3-dimensions, whereas electrolytics are a couple
> > of wound, flat pieces of foil.
> >
> > Due to their inherent structure, tanatalums charge very quickly as
> > the 3-D surface gets easily flooded with electrons, whereas for
> > electrolytics, the electrons have to spread around the plate to be
> > saturated. That takes time.
> >
> > So, tantalums are very good for high frequency cap duties, like on
> > the crystal (clock) circuits. For power rails, electrolytics are
> > fine of course, but for anything that's a high frequency circuit,
> > I'd stick with a tantalum if was spec'ed that way to begin with.
> >
> > Tantalums are very unfogiving of overvoltage which is what usually
> > kills them. Once they're saturated, the slightest voltage over their
> > rating will do them in, where they melt into a short. They work
> > great when used properly in a circuit where the probability that
> > they'll ever see a spike is nil. Replacing a tant with one with a
> > larger rating will slow down the saturation time, so again, I'd just
> > replace it with the original rating component. I like the Vishay
> > brand which is what we use in the aviation industry where I work.
> >;
> > I'm no expert (I'm a mechanical engineer however), but I spent a few
> > hours researching the ins-and-outs of tants one day right before I
> > did a full recap on my OB-Xa. If it was tantalum, it stayed that way.
> >
> > Scott in Ohio
> >
>

--
Met vriendelijke groet / regards

Richard van der Meer

check out my music at:

http://www.youtube.com/ricardodilago

http://soundcloud.com/ricardo-di-lago

Vintage Synth Repair

Yamaha SY77 faulty

Yamaha SY77 faulty

Re: [vintagesynthrepair] Recapping

RE: [vintagesynthrepair] Recapping

Re: [vintagesynthrepair] Recapping

Re: Yamaha SY77 faulty

RE: [vintagesynthrepair] Re: Yamaha SY77 faulty

RE: [vintagesynthrepair] Recapping

Re: [vintagesynthrepair] Recapping

Re: Yamaha SY77 faulty

Re: Yamaha SY77 faulty

Re: Yamaha SY77 faulty

Re: [vintagesynthrepair] Recapping

Re: [vintagesynthrepair] Recapping

Re: Recapping

Re: [vintagesynthrepair] Re: Recapping

Re: [vintagesynthrepair] Re: Recapping

Re: [vintagesynthrepair] Re: Recapping

Move to quarantaine