Vintage Synth Repair

a crippled dw8000 was recently passed on to me. at first i thought it 
was the key contact problem i read about, but further inspection 
revealed that within the first minute or so of turning it on, the keys 
do trigger and also it will trigger thru midi. the problem is that the 
output sound is complete distortion and not related at all to the actual 
programmed sound. i know this because every once in awhile i will hear 
the real sound for a second or two. the distortion will carry on for a 
couple minutes, then fade into silence. somtimes the distortion will 
return thru continued playing of the keys or midi input, but it always 
cuts out or fades again. if i switch it off for a few seconds and back 
on, sometimes the distortion will appear again. the battery seems fine 
as parameter changes are retained in memory. can anyone suggest what 
these symptoms indicate and what i need to do to fix it? could it be a 
faulty power supply? there is a sticker on the unit that says "enermax 
power inside". is this the factory power supply for the dw8000 or has it 
been replaced?
thanks,
shayne

I've had a DW8000 since 1989 and never had this problem (or any others) and
everything is original including the back-up battery.
Ralph


   Date: Wed, 18 Aug 2004 01:19:40 -0600

   From: Shayne Cafferata <scafferata@...>
Subject: 

a crippled dw8000 was recently passed on to me. at first i thought it 
was the key contact problem i read about, but further inspection 
revealed that within the first minute or so of turning it on, the keys 
do trigger and also it will trigger thru midi. the problem is that the 
output sound is complete distortion and not related at all to the actual 
programmed sound. i know this because every once in awhile i will hear 
the real sound for a second or two. the distortion will carry on for a 
couple minutes, then fade into silence. somtimes the distortion will 
return thru continued playing of the keys or midi input, but it always 
cuts out or fades again. if i switch it off for a few seconds and back 
on, sometimes the distortion will appear again. the battery seems fine 
as parameter changes are retained in memory. can anyone suggest what 
these symptoms indicate and what i need to do to fix it? could it be a 
faulty power supply? there is a sticker on the unit that says "enermax 
power inside". is this the factory power supply for the dw8000 or has it 
been replaced?
thanks,
shayne

...just yesterday i had to chase down a similar problem in a 
proteus.  i replaced the battery (it read full voltage, but that 
doesn't mean it will stay constant with a load on it), and resolderd 
all the connectors, cables, and especially voltage regulators (both 
in the powersupply and on the main board)....runs like a champ now.  
i'm not sure what the culprit was, but at it's age, it certainly was 
going to need a battery and resoldering soon (those voltage regs get 
hot).

deknow


--- In vintagesynthrepair@yahoogroups.com, Detko.Ralph@i... wrote:
> I've had a DW8000 since 1989 and never had this problem (or any 
others) and
> everything is original including the back-up battery.
> Ralph
> 
> 
>    Date: Wed, 18 Aug 2004 01:19:40 -0600
>    From: Shayne Cafferata <scafferata@s...>
> Subject: 
> 
> a crippled dw8000 was recently passed on to me. at first i thought 
it 
> was the key contact problem i read about, but further inspection 
> revealed that within the first minute or so of turning it on, the 
keys 
> do trigger and also it will trigger thru midi. the problem is that 
the 
> output sound is complete distortion and not related at all to the 
actual 
> programmed sound. i know this because every once in awhile i will 
hear 
> the real sound for a second or two. the distortion will carry on 
for a 
> couple minutes, then fade into silence. somtimes the distortion 
will 
> return thru continued playing of the keys or midi input, but it 
always 
> cuts out or fades again. if i switch it off for a few seconds and 
back 
> on, sometimes the distortion will appear again. the battery seems 
fine 
> as parameter changes are retained in memory. can anyone suggest 
what 
> these symptoms indicate and what i need to do to fix it? could it 
be a 
> faulty power supply? there is a sticker on the unit that 
says "enermax 
> power inside". is this the factory power supply for the dw8000 or 
has it 

> been replaced?
> thanks,
> shayne

Look over the printed circuit boards for small
electrolytic capacitors that are leaking electrolyte.
You will probably find lands on the board that have
been damaged. Clean and repair both sides of the board
and replace the defective capacitors.
-Bob

--- Shayne Cafferata <scafferata@...> wrote:

> a crippled dw8000 was recently passed on to me. at
> first i thought it 
> was the key contact problem i read about, but
> further inspection 
> revealed that within the first minute or so of
> turning it on, the keys 
> do trigger and also it will trigger thru midi. the
> problem is that the 
> output sound is complete distortion and not related
> at all to the actual 
> programmed sound. i know this because every once in
> awhile i will hear 
> the real sound for a second or two. the distortion
> will carry on for a 
> couple minutes, then fade into silence. somtimes the
> distortion will 
> return thru continued playing of the keys or midi
> input, but it always 
> cuts out or fades again. if i switch it off for a
> few seconds and back 
> on, sometimes the distortion will appear again. the
> battery seems fine 
> as parameter changes are retained in memory. can
> anyone suggest what 
> these symptoms indicate and what i need to do to fix
> it? could it be a 
> faulty power supply? there is a sticker on the unit
> that says "enermax 
> power inside". is this the factory power supply for
> the dw8000 or has it 
> been replaced?
> thanks,
> shayne
> 
> 


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Look over the printed circuit boards for small
electrolytic capacitors that are leaking electrolyte.
You will probably find lands on the board that have
been damaged. Clean and repair both sides of the board
and replace the defective capacitors.
-Bob

...just yesterday i had to chase down a similar problem in a 
proteus.  i replaced the battery (it read full voltage, but that 
doesn't mean it will stay constant with a load on it), and resolderd 
all the connectors, cables, and especially voltage regulators (both 
in the powersupply and on the main board)....runs like a champ now.  
i'm not sure what the culprit was, but at it's age, it certainly was 
going to need a battery and resoldering soon (those voltage regs get 
hot).

deknow