Xpantastic!

Voice 1 seems to be bad, so I've turned it off.

With Voice 1 Off, This is the status of Autotune

VCOs- PASS
PW - PASS
RES- PASS
VCF- PASS
VCA- FAIL
(With VCO1 on, all the above tests FAIL.)

On Master Page, Page 2, Voices On.OFF, All Voices show FAIL

DAC Tests
 DAC Mono- Page 2 LED blinks about 2 times per second (Is this good or
bad? Nothing in the service manual about the blink Rate.

I hear a Buzz in the audio- which sounds like a sawtooth going about 5
times per second.

DAC OFFSET- Page 2 LED blinks about 2 times per second. Good or bad?

All other tests on the Service Page are OK

> Out of tune Points to the DAC, pray it's is not failed because it's
> even harder to find than the CEMs.


> Can you tell if the filter still sweeps well? Or - Turn off the VCO
> waves and turn the resonace all the way up,and the cutoff all the way
> down, Mod by keyboard to see if you can play the filter like a voice.

Self resonating? Yes.

> Once we know if it's the DAC or
> not we can go from there.

Also- after hitting untune on the DAC page, then doing auto tune, my
VCOs sound much better. In tune, that is.

So- it only looks like Voice 1 is fialing, and the VCA test.

Now what ?

Hi Tony,

Power Supply:
If you have a buzz in the audio output Then the power supply may be 
going. An easy way to tell is to get a new large capacitor of the 
same value and voltage . And use jumper leads to jump it across the 
suspect cap. If the buzz goes away then Replace Em. You will probobly
not be able to find exact matches. So some retrofitting may be in 
order. 
You probobly know this Tony, but these caps have a polarity to them. 
So you have to notice where + is and put the new one in the same 
way.  + to +.  Also you can go higher in capacitance and voltage 
ratings but not lower.


Voice 1 Problem:
I suspect a bypass capacitor located at the output of each voice. I 
keep seeing this part failing in more and more M12/Xpanders.( mine 
included) So get a new 2.2uF 50 volt electrolytic cap. and replace 
C749 (for Voice 1). It is toward the front of the board. This same 
value part is all over the voice circuits. So.. It would not be a bad 
Idea to get a bunch of em, and replace all Cx49s. Again you gotta 
observe polarity.

I don't know about the DAC mono test, but if you can get the voices 
to tune, then the DAC's probobly good.

Good Luck
Karl


--- In xpantastic@yahoogroups.com, "Tony Cappellini" <cappy2112@...> 
wrote:
>
> Voice 1 seems to be bad, so I've turned it off.
> 
> With Voice 1 Off, This is the status of Autotune
> 
> VCOs- PASS
> PW - PASS
> RES- PASS
> VCF- PASS
> VCA- FAIL
> (With VCO1 on, all the above tests FAIL.)
> 
> On Master Page, Page 2, Voices On.OFF, All Voices show FAIL
> 
> DAC Tests
>  DAC Mono- Page 2 LED blinks about 2 times per second (Is this good 
or
> bad? Nothing in the service manual about the blink Rate.
> 
> I hear a Buzz in the audio- which sounds like a sawtooth going 
about 5
> times per second.
> 
> DAC OFFSET- Page 2 LED blinks about 2 times per second. Good or bad?
> 
> All other tests on the Service Page are OK
> 
> > Out of tune Points to the DAC, pray it's is not failed because 
it's
> > even harder to find than the CEMs.
> 
> 
> > Can you tell if the filter still sweeps well? Or - Turn off the 
VCO
> > waves and turn the resonace all the way up,and the cutoff all the 
way
> > down, Mod by keyboard to see if you can play the filter like a 
voice.

> 
> Self resonating? Yes.
> 
> > Once we know if it's the DAC or
> > not we can go from there.
> 
> Also- after hitting untune on the DAC page, then doing auto tune, my
> VCOs sound much better. In tune, that is.
> 
> So- it only looks like Voice 1 is fialing, and the VCA test.
> 
> Now what ?
>

> Power Supply:
> If you have a buzz in the audio output Then the power supply may be
> going.

Perhaps I should upload a short mp3 of it and let the court decide.

Would someone upload (or just email me) an mp3 of what I should be
hearing during the Dac test- just so I know what to expect in the
future?


I will try your suggestions Karl, thanks for the tips.

BTW My Xpander came to life after I pressed Untune, then ran Autotune.
The output level is much higher, and has more presence.

Before- when I posted the message about looking for someone local to
do a side by side audio comparsion- my XPander had a weak output and
sounded
dull.

Hey Tony,

I was looking in the Xpander Service Manual. I Have a PDF copy, but I 
don't remember were I got it. Anyway, It says that When you do the 
DAC mono test you should hear none or very seldom beep on the audio. 
But thats it, nothing on what to do if you hear lots of beeps
(page 35) 
The next page describes a software reset - Hold down clear (at the 
end of the MOD row) And turn Power On. The M12 service manual has 
none of this.

--- In xpantastic@yahoogroups.com, "Tony Cappellini" <cappy2112@...> 
>wrote:
> BTW My Xpander came to life after I pressed Untune, then ran 
> Autotune. The output level is much higher, and has more presence.

You know, I have done really bizzare mod stuff with mine (every  
mod routed to itself etc..) I have sometimes locked it up. Maybe you 
created a ghost in the machine and the untuning / retuning fixed it. 
The manual says untuning clears all the software clibration 
registers.  

Karl

Hi Tony,

I did find this link to some xpander pages in PDF:

http://matrix-12.tripod.com/home.htm

Karl

All of you,

Guys, trust Karl: he's a genius. He fixed my Xpander in no time
across the atlantic !! Do exactly the steps he recommends.
Best regards to all,
Philippe

I will.
I hope to take a look inside this weekend. During the week is difficult


>>He fixed my Xpander in no time across the atlantic
Karl- my car is making a noise that also sounds like my Xpander.
Any idea what is wrong ;-)

On Fri, Sep 5, 2008 at 8:23 AM, philipperyckman <caractere@...> wrote:
> All of you,
>
> Guys, trust Karl: he's a genius. He fixed my Xpander in no time
> across the atlantic !! Do exactly the steps he recommends.
> Best regards to all,
> Philippe
>
>

There�s nothing wrong with it,- use it as a synth ...
Try to create a wovel sounding selfplaying patch which sings the song 
"Rolling Home" ...

:-D

>
> Karl- my car is making a noise that also sounds like my Xpander.
> Any idea what is wrong ;-)
>
>

Thanks. I have an original Xander srvice manual, with color schematics.

Karl,
I went through all the DC voltmeter measurements in the service manuel.
Everything looks good (to me) except for Step 3, +5M text.
On the right side of D4 (as I am facing the Processor Board, sometimes
I measured 6.6 v, other times I measured 3.9 to 4.9 volts.
I suspect there is a bad solder joing on D4, so I will reflow this.


> Power Supply:
> If you have a buzz in the audio output Then the power supply may be
> going. An easy way to tell is to get a new large capacitor of the
> same value and voltage . And use jumper leads to jump it across the
> suspect cap. If the buzz goes away then Replace Em. You will probobly
> not be able to find exact matches. So some retrofitting may be in
> order.

I looked at C3 and there is some dry dusty residue on the negative side of C3.
There is less residue on the negative side of C1.

These caps are old, so I might as well just replace them all at the same time.
There are 4 more electrolytic caps on the PS board, but their leads
are right up against the PCB, so I can't see if they are leaking.

> Voice 1 Problem:
> I suspect a bypass capacitor located at the output of each voice. I
> keep seeing this part failing in more and more M12/Xpanders.( mine
> included) So get a new 2.2uF 50 volt electrolytic cap. and replace
> C749 (for Voice 1). It is toward the front of the board. This same
> value part is all over the voice circuits. So.. It would not be a bad
> Idea to get a bunch of em, and replace all Cx49s. Again you gotta
> observe polarity.

I dont want to trust my baby Xpander to my shaky hands that haven't
used a soldering iron regularly since 1985, so I will have a pro do
this for me.
It will be worth the money to have all the voices re-capped.

>
> I don't know about the DAC mono test, but if you can get the voices
> to tune, then the DAC's probobly good.

In a previous email you referred to a RARE DAC. The service manual
references several whose part numbers look like easy to find
components to me.
Which rare DAC are you referring to?

Thanks


Tony

Hi Tony,
Have been out of pocket for a few days ( building a parade float).
Back now.
--- In xpantastic@yahoogroups.com, "Tony Cappellini" <cappy2112@...> 
wrote:
> I went through all the DC voltmeter measurements in the service 
> manuel. Everything looks good (to me) except for Step 3, +5M text.
> On the right side of D4 (as I am facing the Processor Board, 
> sometimes I measured 6.6 v, other times I measured 3.9 to 4.9 volts.
> I suspect there is a bad solder joing on D4, so I will reflow this.

6.6 V seems very strange for the memory power supply. The battary 
might need changing. 
If you are re-flowing the + side of this circuit ( M+5V) you better 
make sure you have an un-grounded soldering Iron.  If not 
the +Mem supply will be shorted to ground and then the MEM will be 
lost.
Hope I caught you in time.
I notice in the Xpander schematics D4 exsists twice. One is a diode 
at the top edge of the board the other is an LED for the LFO.  Now I 
am sure you know the difference between a diode and an LED but I 
thought I would mention it. This was changed in the M12 schems.

> I looked at C3 and there is some dry dusty residue on the negative 
> side of C3.
> There is less residue on the negative side of C1.
If this is shiny brown, this may be soldering flux. This should 
always be cleaned off the circuit board.
After about 5 - 10 years this will eat the solder and cause problems

> These caps are old, so I might as well just replace them all at the 
> same time.
> There are 4 more electrolytic caps on the PS board, but their leads
> are right up against the PCB, so I can't see if they are leaking.
I have not seen this in Oberheims, but many times in old Korgs / 
Rolands.
 
> It will be worth the money to have all the voices re-capped.
Good Idea, I am thinking off doing this myself. When I change my 
battary.

> In a previous email you referred to a RARE DAC. The service manual
> references several whose part numbers look like easy to find
> components to me.
> Which rare DAC are you referring to?

Well, I be talkin about U811 the main DAC which feeds the voice 
board. The MP7614C-4 was mad by EXAR and is obsolete per their web 
site, and the HS3140C-4 was made by SIPEX and is also obsolete.
I suppose with digging you can find this part out there somewhere
(repair shop or part house which specializes in obsolete parts but
you will pay quite a bit).

Good Luck 

Karl

Thanks Phillipe,
You are too kind. Truth is, You fixed it by doing all the 
heavy lifting(real work).
I just made some suggestions.
Glad I Could Help
Karl 


--- In xpantastic@yahoogroups.com, "philipperyckman" <caractere@...> 
wrote:

>
> All of you,
> 
> Guys, trust Karl: he's a genius. He fixed my Xpander in no time
> across the atlantic !! Do exactly the steps he recommends.
> Best regards to all,
> Philippe
>

> 6.6 V seems very strange for the memory power supply. The battary
> might need changing.
The Service manual reads that this should be 4.4 V with power on, and
2.xV with power off.
With power off, the voltage reading is correct.

I will probably change the battery too, since it's been about 10 years
after it was changed last.

> If you are re-flowing the + side of this circuit ( M+5V) you better
> make sure you have an un-grounded soldering Iron. If not
> the +Mem supply will be shorted to ground and then the MEM will be
> lost.

I will have the solder tech where I work do all of this for me  since
he does soldering all day long.
I dont trust myself soldering on pcbs. He has a nice temperature
controlled iron with many removable tips.

> Hope I caught you in time.
I havne't heard of an ungrounded soldering iron before, but I assume
you mean that the iron should not have the ground prong of the
power cord connected. This is easily done with an adapter.


> I notice in the Xpander schematics D4 exsists twice. One is a diode
> at the top edge of the board the other is an LED for the LFO. Now I
The D4 I'm referring to is on the Processor board-not the voice or pot
board. This is how the service manual refers to it.


> If this is shiny brown, this may be soldering flux. This should
> always be cleaned off the circuit board.
> After about 5 - 10 years this will eat the solder and cause problems

It doesn't look like flux too me, and is far enough away from where
the solder flux would have been when it was soldered.


> Well, I be talkin about U811 the main DAC which feeds the voice
> board. The MP7614C-4 was mad by EXAR and is obsolete per their web
> site, and the HS3140C-4 was made by SIPEX and is also obsolete.

I googled for this part, and many hits were found on websites that
specialize in getting rare parts.
They want orders of $100 or more.

It might not be a bad idea for us to do a group purchase of these, if
we could find a supplier who would sell us a small order.

> I suppose with digging you can find this part out there somewhere
> (repair shop or part house which specializes in obsolete parts but
> you will pay quite a bit).

I wish there was a cross reference online that would tell you which
commercial devices also used these components
It would be much easier looking for an appliance than a chip.

If your xpander is not plugged into anything (e.g. the wall) while unsoldering the battery, I it shouldn't matter if the iron is grounded or not because there will be no circuit to complete!  Just make sure your xpander's not plugged in, and its chassis isn't touching the same ground that the iron's grounded to (like the chassis of another plugged-in device) and you should be OK.
 
MHO,
Randy

--- On Sun, 9/7/08, Tony Cappellini <cappy2112@gmail.com> wrote:

From: Tony Cappellini <cappy2112@...>
Subject: Re: The Status of my Autotune & DAC Tests was Re: [xpantastic] Re: It's official- my Xpander is sick
To: xpantastic@yahoogroups.com
Date: Sunday, September 7, 2008, 12:11 PM






> 6.6 V seems very strange for the memory power supply. The battary
> might need changing.
The Service manual reads that this should be 4.4 V with power on, and
2.xV with power off.
With power off, the voltage reading is correct.

I will probably change the battery too, since it's been about 10 years
after it was changed last.

> If you are re-flowing the + side of this circuit ( M+5V) you better
> make sure you have an un-grounded soldering Iron. If not
> the +Mem supply will be shorted to ground and then the MEM will be
> lost.

I will have the solder tech where I work do all of this for me since
he does soldering all day long.
I dont trust myself soldering on pcbs. He has a nice temperature
controlled iron with many removable tips.

> Hope I caught you in time.
I havne't heard of an ungrounded soldering iron before, but I assume
you mean that the iron should not have the ground prong of the
power cord connected. This is easily done with an adapter.

> I notice in the Xpander schematics D4 exsists twice. One is a diode
> at the top edge of the board the other is an LED for the LFO. Now I
The D4 I'm referring to is on the Processor board-not the voice or pot
board. This is how the service manual refers to it.

> If this is shiny brown, this may be soldering flux. This should
> always be cleaned off the circuit board.
> After about 5 - 10 years this will eat the solder and cause problems

It doesn't look like flux too me, and is far enough away from where
the solder flux would have been when it was soldered.

> Well, I be talkin about U811 the main DAC which feeds the voice
> board. The MP7614C-4 was mad by EXAR and is obsolete per their web
> site, and the HS3140C-4 was made by SIPEX and is also obsolete.

I googled for this part, and many hits were found on websites that
specialize in getting rare parts.
They want orders of $100 or more.

It might not be a bad idea for us to do a group purchase of these, if
we could find a supplier who would sell us a small order.

> I suppose with digging you can find this part out there somewhere
> (repair shop or part house which specializes in obsolete parts but
> you will pay quite a bit).

I wish there was a cross reference online that would tell you which
commercial devices also used these components
It would be much easier looking for an appliance than a chip.

Hi Tony,

> > Well, I be talkin about U811 the main DAC which feeds the voice
> > board. The MP7614C-4 was mad by EXAR and is obsolete per their web
> > site, and the HS3140C-4 was made by SIPEX and is also obsolete.
--- In xpantastic@yahoogroups.com, "Tony Cappellini" >wrote:
> I googled for this part, and many hits were found on websites that
> specialize in getting rare parts.
> They want orders of $100 or more.

What was the cost per part?

I have a problem every once in a while (well, more and more lately) when a part for a current product goes obsolete. What is not so clear on a web search is a lot of these "rare part" companies are working from the same stock of parts. They trade and post each other's part lists. So although you may get dozens or even hundreds of hits there are usually only a few parts out there. Last year I went looking for a very recently obsoleted part. When it was all said and done. The parts I was looking for were in Italy, there were only 25 of them, and I would have had to Pay $85.00 USA a piece + shipping. All for a part that a few months ago I was only paying $7.00 for. It was cheaper at that point to redesign.

Most of the generic logic chips in the Xpander/M12 are still
available, however many companys are discontinuing many of their
through hole parts due to:
1) Surface Mount Parts are becoming the rule of the day
2) ROHS (lead free) export rules.

> I wish there was a cross reference online that would tell you >which
> commercial devices also used these components
> It would be much easier looking for an appliance than a chip.

Tony, you may already know this but

http://www.synthtech.com/cem/cemsynth.html

has a nice list of analog synthesizers and what CEM parts are used. It's not everything but it's a start

Best Regards
Karl

Hello Randy,

Sounds right to me.  I was thinking of the times  I have seen techs
leave the synth plugged in and powered up to avoid dumping the memory.
It takes guts but some guys do it.

Best Regards

Karl
--- In xpantastic@yahoogroups.com, William Cason <randycason102@...>
wrote:
>
> If your xpander is not plugged into anything (e.g. the wall) while
unsoldering the battery, I it shouldn't matter if the iron is grounded
or not because there will be no >circuit to complete!  Just make sure
your xpander's not plugged in, and its chassis isn't touching the same
ground that the iron's grounded to (like the chassis of another
>plugged-in device) and you should be OK.
>
> MHO,
> Randy
>
> --- On Sun, 9/7/08, Tony Cappellini cappy2112@... wrote:
>
> From: Tony Cappellini cappy2112@...
> Subject: Re: The Status of my Autotune & DAC Tests was Re:
[xpantastic] Re: It's official- my Xpander is sick

> To: xpantastic@yahoogroups.com
> Date: Sunday, September 7, 2008, 12:11 PM
>
>
>
>
>
>
> > 6.6 V seems very strange for the memory power supply. The battary
> > might need changing.
> The Service manual reads that this should be 4.4 V with power on, and
> 2.xV with power off.
> With power off, the voltage reading is correct.
>
> I will probably change the battery too, since it's been about 10 years
> after it was changed last.
>
> > If you are re-flowing the + side of this circuit ( M+5V) you better
> > make sure you have an un-grounded soldering Iron. If not
> > the +Mem supply will be shorted to ground and then the MEM will be
> > lost.
>
> I will have the solder tech where I work do all of this for me since
> he does soldering all day long.
> I dont trust myself soldering on pcbs. He has a nice temperature
> controlled iron with many removable tips.
>
> > Hope I caught you in time.
> I havne't heard of an ungrounded soldering iron before, but I assume
> you mean that the iron should not have the ground prong of the
> power cord connected. This is easily done with an adapter.
>
> > I notice in the Xpander schematics D4 exsists twice. One is a diode
> > at the top edge of the board the other is an LED for the LFO. Now I
> The D4 I'm referring to is on the Processor board-not the voice or pot
> board. This is how the service manual refers to it.
>
> > If this is shiny brown, this may be soldering flux. This should
> > always be cleaned off the circuit board.
> > After about 5 - 10 years this will eat the solder and cause problems
>
> It doesn't look like flux too me, and is far enough away from where
> the solder flux would have been when it was soldered.
>
> > Well, I be talkin about U811 the main DAC which feeds the voice
> > board. The MP7614C-4 was mad by EXAR and is obsolete per their web
> > site, and the HS3140C-4 was made by SIPEX and is also obsolete.
>
> I googled for this part, and many hits were found on websites that
> specialize in getting rare parts.
> They want orders of $100 or more.
>
> It might not be a bad idea for us to do a group purchase of these, if
> we could find a supplier who would sell us a small order.
>
> > I suppose with digging you can find this part out there somewhere
> > (repair shop or part house which specializes in obsolete parts but
> > you will pay quite a bit).
>
> I wish there was a cross reference online that would tell you which
> commercial devices also used these components
> It would be much easier looking for an appliance than a chip.
>

> > They want orders of $100 or more.
>
> What was the cost per part?

Nothing is ever posted on these sites, you have to call and tell them
how many you want to buy.
Even at $50-$100 a piece, it's better than letting a $1600 (or more)
synth lay useless, if the part ever failed.

>>that a few months ago I was only paying $7.00 for. It was cheaper at that point to redesign.
How are you going to resdesign and manufacture an IC unless you have a
semiconductor fab & mfg + experience doing it?

> http://www.synthtech.com/cem/cemsynth.html
yes- many of the CEMs he has listed are alreayd sold out.
I got the last 3372 and a 3340, and still have some others from many years ago.
I don't have any 3374's though, but I heard these dont go bad on the
XP/M12 very often.

When I first moved to San Jose, I went to the company here that was
still selling these chips for $15, and bought a handfull.

Hmmm, never thought of that one!
 
Randy

--- On Tue, 9/9/08, Karl <shire03@...> wrote:

From: Karl <shire03@...>
Subject: The Status of my Autotune & DAC Tests was Re: [xpantastic] Re: It's official- my Xpander is sick
To: xpantastic@yahoogroups.com
Date: Tuesday, September 9, 2008, 1:03 AM







Hello Randy,

Sounds right to me. I was thinking of the times I have seen techs
leave the synth plugged in and powered up to avoid dumping the memory.
It takes guts but some guys do it.

Best Regards

Karl
--- In xpantastic@yahoogro ups.com, William Cason <randycason102@ ...>
wrote:
>
> If your xpander is not plugged into anything (e.g. the wall) while
unsoldering the battery, I it shouldn't matter if the iron is grounded
or not because there will be no >circuit to complete! Just make sure
your xpander's not plugged in, and its chassis isn't touching the same
ground that the iron's grounded to (like the chassis of another
>plugged-in device) and you should be OK.
>
> MHO,
> Randy
>
> --- On Sun, 9/7/08, Tony Cappellini cappy2112@.. . wrote:
>
> From: Tony Cappellini cappy2112@.. .
> Subject: Re: The Status of my Autotune & DAC Tests was Re:
[xpantastic] Re: It's official- my Xpander is sick

> To: xpantastic@yahoogro ups.com
> Date: Sunday, September 7, 2008, 12:11 PM
>
>
>
>
>
>
> > 6.6 V seems very strange for the memory power supply. The battary
> > might need changing.
> The Service manual reads that this should be 4.4 V with power on, and
> 2.xV with power off.
> With power off, the voltage reading is correct.
>
> I will probably change the battery too, since it's been about 10 years
> after it was changed last.
>
> > If you are re-flowing the + side of this circuit ( M+5V) you better
> > make sure you have an un-grounded soldering Iron. If not
> > the +Mem supply will be shorted to ground and then the MEM will be
> > lost.
>
> I will have the solder tech where I work do all of this for me since
> he does soldering all day long.
> I dont trust myself soldering on pcbs. He has a nice temperature
> controlled iron with many removable tips.
>
> > Hope I caught you in time.
> I havne't heard of an ungrounded soldering iron before, but I assume
> you mean that the iron should not have the ground prong of the
> power cord connected. This is easily done with an adapter.
>
> > I notice in the Xpander schematics D4 exsists twice. One is a diode
> > at the top edge of the board the other is an LED for the LFO. Now I
> The D4 I'm referring to is on the Processor board-not the voice or pot
> board. This is how the service manual refers to it.
>
> > If this is shiny brown, this may be soldering flux. This should
> > always be cleaned off the circuit board.
> > After about 5 - 10 years this will eat the solder and cause problems
>
> It doesn't look like flux too me, and is far enough away from where
> the solder flux would have been when it was soldered.
>
> > Well, I be talkin about U811 the main DAC which feeds the voice
> > board. The MP7614C-4 was mad by EXAR and is obsolete per their web
> > site, and the HS3140C-4 was made by SIPEX and is also obsolete.
>
> I googled for this part, and many hits were found on websites that
> specialize in getting rare parts.
> They want orders of $100 or more.
>
> It might not be a bad idea for us to do a group purchase of these, if
> we could find a supplier who would sell us a small order.
>
> > I suppose with digging you can find this part out there somewhere
> > (repair shop or part house which specializes in obsolete parts but
> > you will pay quite a bit).
>
> I wish there was a cross reference online that would tell you which
> commercial devices also used these components
> It would be much easier looking for an appliance than a chip.
>

Since the VFD's have a limited life, you may not want to leave them on
all the time.

On Tue, Sep 9, 2008 at 4:17 PM, William Cason <randycason102@...> wrote:
> Hmmm, never thought of that one!
>
> Randy
>
> --- On Tue, 9/9/08, Karl <shire03@...> wrote:
>
> From: Karl <shire03@...>
> Subject: The Status of my Autotune & DAC Tests was Re: [xpantastic] Re: It's
> official- my Xpander is sick
> To: xpantastic@yahoogroups.com
> Date: Tuesday, September 9, 2008, 1:03 AM
>
>
> Hello Randy,
>
> Sounds right to me. I was thinking of the times I have seen techs
> leave the synth plugged in and powered up to avoid dumping the memory.
> It takes guts but some guys do it.
>
> Best Regards
>
> Karl
> --- In xpantastic@yahoogro ups.com, William Cason <randycason102@ ...>
> wrote:
>>
>> If your xpander is not plugged into anything (e.g. the wall) while
> unsoldering the battery, I it shouldn't matter if the iron is grounded
> or not because there will be no >circuit to complete! Just make sure
> your xpander's not plugged in, and its chassis isn't touching the same
> ground that the iron's grounded to (like the chassis of another
>>plugged-in device) and you should be OK.
>>
>> MHO,
>> Randy
>>
>> --- On Sun, 9/7/08, Tony Cappellini cappy2112@.. . wrote:
>>
>> From: Tony Cappellini cappy2112@.. .
>> Subject: Re: The Status of my Autotune & DAC Tests was Re:
> [xpantastic] Re: It's official- my Xpander is sick
>> To: xpantastic@yahoogro ups.com
>> Date: Sunday, September 7, 2008, 12:11 PM
>>
>>
>>
>>
>>
>>
>> > 6.6 V seems very strange for the memory power supply. The battary
>> > might need changing.
>> The Service manual reads that this should be 4.4 V with power on, and
>> 2.xV with power off.
>> With power off, the voltage reading is correct.
>>
>> I will probably change the battery too, since it's been about 10 years
>> after it was changed last.
>>
>> > If you are re-flowing the + side of this circuit ( M+5V) you better
>> > make sure you have an un-grounded soldering Iron. If not
>> > the +Mem supply will be shorted to ground and then the MEM will be
>> > lost.
>>
>> I will have the solder tech where I work do all of this for me since
>> he does soldering all day long.
>> I dont trust myself soldering on pcbs. He has a nice temperature
>> controlled iron with many removable tips.
>>
>> > Hope I caught you in time.
>> I havne't heard of an ungrounded soldering iron before, but I assume
>> you mean that the iron should not have the ground prong of the
>> power cord connected. This is easily done with an adapter.
>>
>> > I notice in the Xpander schematics D4 exsists twice. One is a diode
>> > at the top edge of the board the other is an LED for the LFO. Now I
>> The D4 I'm referring to is on the Processor board-not the voice or pot
>> board. This is how the service manual refers to it.
>>
>> > If this is shiny brown, this may be soldering flux. This should
>> > always be cleaned off the circuit board.
>> > After about 5 - 10 years this will eat the solder and cause problems
>>
>> It doesn't look like flux too me, and is far enough away from where
>> the solder flux would have been when it was soldered.
>>
>> > Well, I be talkin about U811 the main DAC which feeds the voice
>> > board. The MP7614C-4 was mad by EXAR and is obsolete per their web
>> > site, and the HS3140C-4 was made by SIPEX and is also obsolete.
>>
>> I googled for this part, and many hits were found on websites that
>> specialize in getting rare parts.
>> They want orders of $100 or more.
>>
>> It might not be a bad idea for us to do a group purchase of these, if
>> we could find a supplier who would sell us a small order.
>>
>> > I suppose with digging you can find this part out there somewhere
>> > (repair shop or part house which specializes in obsolete parts but
>> > you will pay quite a bit).
>>
>> I wish there was a cross reference online that would tell you which
>> commercial devices also used these components
>> It would be much easier looking for an appliance than a chip.
>>
>
>
>