[sdiy] Prophet 5 rev2 conundrum

antti.s.pitkamaki at gmail.com antti.s.pitkamaki at gmail.com
Sat May 13 12:05:14 CEST 2023


My Yamaha CS40M had a similar ”crack” as this rev2. It concerned the EG generators, which went totally cockoo bananas. I thought the ADSR-sliders just needed good cleaning. Continuity checks showed there are no continuity problems. But finally the reason was cracked solder joints on the ADSR-sliders. Probing the joints pushed them enough to create continuity, so it took a while before I realized what was going on.

Cha cha cha,
Antti

Lähetetty iPhonesta

> Michael E Caloroso via Synth-diy <synth-diy at synth-diy.org> kirjoitti 13.5.2023 kello 5.18:
> 
> 
> Memorymoog owner since 1986.  The first time I opened it up to calibrate the voicecards, the tuning trimpots lifted right off the circuit boards out of their solder fillets.
> 
> Malfunctions on other gear were cured when I reflowed the fillets.
> 
> Just because the fillets look good doesn't mean they are.
> 
> MC
> 
>> On Fri, May 12, 2023 at 1:56 PM Terry Bowman via Synth-diy <synth-diy at synth-diy.org> wrote:
>> 
>>> On May 12, 2023, at 5:35 AM, Roman Sowa <modular at go2.pl> wrote:
>>> 
>>> A broken track or solder joint is the most difficult fault to find.
>>> Especially when the PCB is the size of Wyoming with milion solder joints.
>> 
>> 
>> I used to work cable TV line extenders. There was a Jerrold power supply with a stud mounted bridge rectifier bolted to the chassis. The leads came up through holes on the PC board. The holes had hollow rivets/eyelets to protect the traces. I spent many hours trying to find an intermittent and in the end it turned out to be a loose eyelet. It looked perfect, had a ton of solder on it.
>> 
>> Or have I told this story before? Hmm...
>> 
>> 
>> Terry Bowman, KA4HJH
>> "The Mac Doctor"
>> 
>> https://www.astarcloseup.com
>> 
>> "In the land of the blind the one-eyed man is king"—Max Payne
>> "In regione caecorum rex est luscus"—Desiderius Erasmus
>> 
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