Vintage Synth Repair

The SH-101 powers up normally but the key transpose LED stays lit and 
all the buttons do not work. And it doesn�t make any sound. 
Is this a common and easy problem to fix?

Thanks.

Dont know, but i'd start by checking the power supply.

Phil.

--- inocencio66 <paulo.simoes5@...> wrote:

> The SH-101 powers up normally but the key transpose
> LED stays lit and 
> all the buttons do not work. And it doesn\ufffdt make any
> sound. 
> Is this a common and easy problem to fix?
> 
> Thanks.
> 
> 



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--- In vintagesynthrepair@yahoogroups.com, Philip <eggwheatis@...> 
wrote:
>
> Dont know, but i'd start by checking the power supply.
> 
> Phil.
> 
> --- inocencio66 <paulo.simoes5@...> wrote:
> 
> > The SH-101 powers up normally but the key transpose
> > LED stays lit and 
> > all the buttons do not work. And it doesn´t make any
> > sound. 
> > Is this a common and easy problem to fix?
> > 
> > Thanks.
> > 

Yes, but what to check? The service manual is not of much help; well at 
least not for me: no checkpoints nor voltage references...

It seems to be the CPU giving trouble. What to look for?

I would still check the internal power supply first before doing anything. Nothing will work properly including the CPU if you have a problem here. The service

On one of the websites I found the other day someone mentioned that
the SH-101 and the MC-202 were essentially the same innerds.

This may help , if you come across a schema of the MC-202

Thanks for all the answers.

Yes, checking the psu and power rails makes a lot of sense. Perhaps 
there�s nothing wrong with the cpu chip, but I can�t trace what�s going 
on.

I do own an MC-202 and while the sound gen section is similar to the 
101, the cpu part isn�t. But the manual is much clearer and helps a bit 
to understand how the psu works...

So, just soldered new decoupling caps to the cpu and fixed a few 
possible dry joints and the unit makes sound now (everything from the 
oscs, filter and env works ok, except for the s&h and vco range).

Still the problem remains, this time the hold led is continuously lit 
and the key transpose led lights on and off at a slow, fixed rate. The 
sound is on hold mode autriggering on and off at the same rate. And 
doesn�t respond to keyboard also. 

I�m testing the unit open. Perhaps closing it, with all the ground 
wires from cv/gate connected to the chassis will make it work? Sorry 
for such a dumb question...

--- In vintagesynthrepair@yahoogroups.com, Philip <eggwheatis@...> 
wrote:

> The service manual isn't too great I agree, but I can
> see +9 fed in externally then the internal psu
> generates +5, -5, +15, +14, with all the points marked
> on the schematic.

> 
> Phil.

One more thing: Where exactly are the cheking points for the +5 and -
5? (Assuming +15 and -14 are for the synth section only)I can only 
see a +5v mention next to vr1. 

I may be misinterpreting some symbols in the shematic and wouldn´t 
want to read/adjust voltages with the voltmeter connected to the 
wrong side of a resistor or something... All I could measure well so 
far were +4.8v at cpu chip´s pin 40.

Thank you.

Hi, there are loads of point to check the
voltages..the psu in the bottom left of the schems..

Have a look round the edges of the schematic
drawing..it shows the voltages and the various symbols
that identify the voltages all over the schematic...3
+14 is a black triangle, -5 is a white triangle, +14
is a half black, half white triangle..the +5 is a dot
with a line through it, +9 is an arrow..etc.

Pin 40 on the CPU should be -5, pin 26 is +5 etc
etc...

Phil.


--- inocencio66 <paulo.simoes5@...> wrote:

> --- In vintagesynthrepair@yahoogroups.com, Philip
> <eggwheatis@...> 
> wrote:
> 
> > The service manual isn't too great I agree, but I
> can
> > see +9 fed in externally then the internal psu
> > generates +5, -5, +15, +14, with all the points
> marked
> > on the schematic.
> 
> > 
> > Phil.
> 
> One more thing: Where exactly are the cheking points
> for the +5 and -
> 5? (Assuming +15 and -14 are for the synth section
> only)I can only 
> see a +5v mention next to vr1. 
> 
> I may be misinterpreting some symbols in the
> shematic and wouldn\ufffdt 
> want to read/adjust voltages with the voltmeter
> connected to the 
> wrong side of a resistor or something... All I could
> measure well so 
> far were +4.8v at cpu chip\ufffds pin 40.
> 
> Thank you.
> 
> 
> 



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Phil, thanks once again for your help. I really had no idea.

Seems the power supply is ok as all the checkpoints read ok.
The other day when both the load and transpose leds lit up with sound 
coming out the unit was I guess due to cpu pin 40 being slightly 
shorter than the others, failing continuity test! Vintage Planet 
mention something like this in their spare parts list, btw. After 
fixing it with a bit of wire, the unit went back to the original 
problem: just the transpose led stuck, with no sound.

Nik,

One thing noted: nearly all the pins going from the cpu to the 4050 
chip read 5v dc. Is it "digital information"? I get the same reading on 
all the 4050 outputs, going into ic 9a. 4050 datasheet seems to mention 
this chip should output only 0,5v (but I could be wrong)...

Is this a sign of a fried chip? I have no other clue.

Many thanks.

No problem...

Yes it's pulsing digital signals, and to check them 
you need a logic probe or a scope. 

Then you can probe around the CPU to if you have the
correct activity. A 4050 is a buffer chip..generally
you should see the same signal on the input of the IC
as on the relevant output.

Check that the cpu is not stuck in reset..the reset
pin on the cpu should be high IE +5

Phil.




> 
> One thing noted: nearly all the pins going from the
> cpu to the 4050 
> chip read 5v dc. Is it "digital information"? I get
> the same reading on 
> all the 4050 outputs, going into ic 9a. 4050
> datasheet seems to mention 
> this chip should output only 0,5v (but I could be
> wrong)...
> 
> Is this a sign of a fried chip? I have no other
> clue.
> 
> Many thanks.
> 
> 



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--- In vintagesynthrepair@yahoogroups.com, Philip <eggwheatis@...> 
wrote:
>
> No problem...
> 
> Yes it's pulsing digital signals, and to check them 
> you need a logic probe or a scope. 
> 
> Then you can probe around the CPU to if you have the
> correct activity. A 4050 is a buffer chip..generally
> you should see the same signal on the input of the IC
> as on the relevant output.
> 
> Check that the cpu is not stuck in reset..the reset
> pin on the cpu should be high IE +5
> 
> Phil.

Very good info. 
The cpu pin 4 reads +5. 
After doublechecking, d17 (octave up) is conducting both ways, and 
(very much hopefully!) is what´s confusing the cpu. On Monday morning 
I´ll look for a replacement diode and will post the results. 

Paulo.

Replaced the diode but the problem remains. Even replaced ic7, ic8 and 
ic10, but nothing. It all leads to a faulty cpu chip. I didn�t want to 
go to the neighbourhood shop where they can scan the cpu activity since 
the guys there are not into synths, just tv repair work, but there�s 
nothing more I can do. Unless anyone here knows of more clues to 
diagnose the problem.

Paulo.

I read your post about the diode...you can't measure
diodes reliably in circuit...sure you can do a quick
check but to be sure it is faulty you need to lift one
leg out of the circuit. 

There was probably nothing wrong with it.

I did say you are in logic probe/scop territory and
without those you are working blind.

Phil.


--- inocencio66 <paulo.simoes5@...> wrote:

> Replaced the diode but the problem remains. Even
> replaced ic7, ic8 and 
> ic10, but nothing. It all leads to a faulty cpu
> chip. I didn\ufffdt want to 
> go to the neighbourhood shop where they can scan the
> cpu activity since 
> the guys there are not into synths, just tv repair
> work, but there\ufffds 
> nothing more I can do. Unless anyone here knows of
> more clues to 
> diagnose the problem.
> 
> Paulo.
> 
> 



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--- In vintagesynthrepair@yahoogroups.com, Philip <eggwheatis@...> 
wrote:
>
> I read your post about the diode...you can't measure
> diodes reliably in circuit...sure you can do a quick
> check but to be sure it is faulty you need to lift one
> leg out of the circuit. 
>
> There was probably nothing wrong with it.

Yes, that occurred to me, but these diodes d17...d29 are all in open 
circuits, and their respective switches tested ok. On the pcb they also 
reside between the cpu and the wires going to the other boards, which 
can be easily disconnected to do the measuring. 

> I did say you are in logic probe/scop territory and
> without those you are working blind.
>
>
> Phil.

Yes, I now "see" it.
There´s a large electronics store in Lisbon that sells vintage parts. 
Maybe they still got a tmp80c49 at a vintage price. I´m going there 
right now.

Cheers!

Paulo.

tmp80c49? As far as I know you can use any type of
8049 brand such as a D8049 there are usually some on
ebay.

Phil.

 
--- inocencio66 <paulo.simoes5@...> wrote:

> --- In vintagesynthrepair@yahoogroups.com, Philip
> <eggwheatis@...> 
> wrote:
> >
> > I read your post about the diode...you can't
> measure
> > diodes reliably in circuit...sure you can do a
> quick
> > check but to be sure it is faulty you need to lift
> one
> > leg out of the circuit. 
> >
> > There was probably nothing wrong with it.
> 
> Yes, that occurred to me, but these diodes d17...d29
> are all in open 
> circuits, and their respective switches tested ok.
> On the pcb they also 
> reside between the cpu and the wires going to the
> other boards, which 
> can be easily disconnected to do the measuring. 
> 
> > I did say you are in logic probe/scop territory
> and
> > without those you are working blind.
> >
> >
> > Phil.
> 
> Yes, I now "see" it.
> There\ufffds a large electronics store in Lisbon that
> sells vintage parts. 
> Maybe they still got a tmp80c49 at a vintage price.
> I\ufffdm going there 
> right now.
> 
> Cheers!
> 
> Paulo.
> 
> 
> 
> 



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--- In vintagesynthrepair@yahoogroups.com, Philip <eggwheatis@...> 
wrote:
>
> tmp80c49? As far as I know you can use any type of
> 8049 brand such as a D8049 there are usually some on
> ebay.
> 
> Phil.
That was a very useful information. Thanks. I had assumed the chip had 
to be of the same exact version/batch as stated in the manual. 
But, it has to be 80C49. 8049 won´t work and will overheat TR1. 
Different pinout and voltages (see pin 26): http://www.cpu-
world.com/info/Pinouts/8049.html . Just for future reference.

I ordered some 80C49s from ebay since I couldn´t find any at the store 
I had previously mentioned. Should arrive by Tuesday. I will post the 
results later. 

Paulo.

You can't just replace the CPU 8049 with another 8049, you need get 
it from roland if still available or from other 101 working CPU.

The fact is that the CPU it's programmed, it has an internal ROM. 
the same processor as Polysix, Juno 60 and other synthesizers.

The other option is to take a working CPU and copy the information 
with a burner capable to read and write 8049 and buy a new 8049 or 
8749. The difference between 8049 and 8749 is that the first one you 
can program it just one time and you can't erase the information. 
The 8749 it's the same version as 8049 but it has a EPROM, that you 
can erase it with a UV Eraser.

VintagePlanet.nl has the original replacement, or you can get from 
ebay 8749 CPU and reprogram.

I did this alredy with Juno 60, Polysix and PG-200.





--- In vintagesynthrepair@yahoogroups.com, "inocencio66" 
<paulo.simoes5@...> wrote:
>
> --- In vintagesynthrepair@yahoogroups.com, Philip <eggwheatis@> 
> wrote:
> >
> > tmp80c49? As far as I know you can use any type of
> > 8049 brand such as a D8049 there are usually some on
> > ebay.
> > 
> > Phil.
> That was a very useful information. Thanks. I had assumed the chip 
had 
> to be of the same exact version/batch as stated in the manual. 
> But, it has to be 80C49. 8049 won´t work and will overheat TR1. 
> Different pinout and voltages (see pin 26): http://www.cpu-
> world.com/info/Pinouts/8049.html . Just for future reference.
> 
> I ordered some 80C49s from ebay since I couldn´t find any at the 
store 
> I had previously mentioned. Should arrive by Tuesday. I will post 
the 

> results later. 
> 
> Paulo.
>

On Monday 21 April 2008 10:47, oxygeno1313 wrote:
> You can't just replace the CPU 8049 with another 8049, you need get
> it from roland if still available or from other 101 working CPU.
>
> The fact is that the CPU it's programmed, it has an internal ROM.
> the same processor as Polysix, Juno 60 and other synthesizers.

I was wondering how long it was going to take before somebody brought this 
up. :-)

> The other option is to take a working CPU and copy the information
> with a burner capable to read and write 8049 and buy a new 8049 or
> 8749.

Nope.

> The difference between 8049 and 8749 is that the first one you 
> can program it just one time and you can't erase the information.

That's incorrect.  Those are not "One-time Programmable (aka OTP) devices,  
they're mask-programmed,  which means that this gets done at the factory 
where the chip is made.  Which means that they're only practical for high 
volume applications.

> The 8749 it's the same version as 8049 but it has a EPROM, that you
> can erase it with a UV Eraser.

Yup,  but I'm not sure that you can take one and just drop it into a socket 
that's intended for an 8049 and have everything else work with no changes. A 
detailed examination of the datasheets might answer that one...


-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James 
M Dakin

--- In vintagesynthrepair@yahoogroups.com, "Roy J. Tellason" 
<rtellason@...> wrote:
>
> On Monday 21 April 2008 10:47, oxygeno1313 wrote:
> > You can't just replace the CPU 8049 with another 8049, you need 
get
> > it from roland if still available or from other 101 working CPU.
> >
> > The fact is that the CPU it's programmed, it has an internal ROM.
> > the same processor as Polysix, Juno 60 and other synthesizers.
> 
> I was wondering how long it was going to take before somebody 
brought this 
> up. :-)
> 
> > The other option is to take a working CPU and copy the information
> > with a burner capable to read and write 8049 and buy a new 8049 or
> > 8749.
> 
> Nope.
> 
> > The difference between 8049 and 8749 is that the first one you 
> > can program it just one time and you can't erase the information.
> 
> That's incorrect.  Those are not "One-time Programmable (aka OTP) 
devices,  
> they're mask-programmed,  which means that this gets done at the 
factory 
> where the chip is made.  Which means that they're only practical 
for high 
> volume applications.
> 
> > The 8749 it's the same version as 8049 but it has a EPROM, that 
you
> > can erase it with a UV Eraser.
> 
> Yup,  but I'm not sure that you can take one and just drop it into 
a socket 
> that's intended for an 8049 and have everything else work with no 
changes. A 
> detailed examination of the datasheets might answer that one...
> 
> 
> -- 
> Member of the toughest, meanest, deadliest, most unrelenting -- and
> ablest -- form of life in this section of space,  a critter that can
> be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet 
Masters"
> -
> Information is more dangerous than cannon to a society ruled by 
lies. --James 
> M Dakin
>

Well, the D80C49Cs have not arrived yet but I´ll try them anyway.
Something funny should happen.

Hello.

To anyone who were following this thread, it�s just to say I got a NOS 
CPU chip from Vintage Planet and the problem is now fixed. After 
calibration my 101 shall be as good as new. So, if you ever face the 
same problem with your synth, now you know what to do (and what NOT to 
do hah!).

Thanks to everyone who helped. It was fun and a good education.

Paulo.