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Synth repair

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Synth repair

Postby nickle15 » Thu Sep 24, 2020 3:51 pm

I've been watching some videos of folks performing repairs, or discussing repairs, on old synthesizers. I think my question is pretty simple though I admit to not having a broad range of knowledge on this topic so feel free to add anything that might be helpful.

If a technician replaces electrical components that are shot or no longer perform reliably is the synth in good shape for a longer period of time going forward based on improvements in those components over time? In other words if you have to replace something on a 1983 synth would you expect the synth to perform well for longer than 37 years based on the quality of the new components? Hopefully my question makes sense.

My dad is an electrician, a retired electrical engineer, and a general all around repair superstar. I've been thinking it might be fun to work with him on restoring an old synth if I were to find the right one. But then that got me to thinking about how reliable the synth would be post repair.

Any thoughts and comments are helpful. Thanks!
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Re: Synth repair

Postby desmond » Thu Sep 24, 2020 3:56 pm

It depends, but there are no guarantees with vintage electronics.

As an example, a notorious failure point on old gear is the failing/leaking of capacitorss, so if you had all the caps replaced in your synth, then yes you've improved the reliability of the caps for another decade or so - but that doesn't mean there aren't other parts of the synth which might fail.

And sometimes parts fail for other reasons than age, too.
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Re: Synth repair

Postby nickle15 » Thu Sep 24, 2020 4:01 pm

desmond wrote:It depends, but there are no guarantees with vintage electronics.

As an example, a notorious failure point on old gear is the failing/leaking of capacitorss, so if you had all the caps replaced in your synth, then yes you've improved the reliability of the caps for another decade or so - but that doesn't mean there aren't other parts of the synth which might fail.

And sometimes parts fail for other reasons than age, too.

Excellent points - thanks. When it comes to caps, do you think those are any higher quality today over what would have been used when the synth was new?
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Re: Synth repair

Postby desmond » Thu Sep 24, 2020 4:08 pm

I'm not really much of an electronics guy (there are other here who can speak to this), but in general, a good service, cleaning, replacing known points of failure and a calibration, done properly, will indeed extend the life, usefulness and value of a vintage synth... :thumbup:
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Re: Synth repair

Postby nickle15 » Thu Sep 24, 2020 4:22 pm

desmond wrote:I'm not really much of an electronics guy (there are other here who can speak to this), but in general, a good service, cleaning, replacing known points of failure and a calibration, done properly, will indeed extend the life, usefulness and value of a vintage synth... :thumbup:

Fantastic - thanks for the reply!
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Re: Synth repair

Postby desmond » Thu Sep 24, 2020 4:22 pm

You're welcome - good luck! :thumbup:
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Re: Synth repair

Postby James Perrett » Thu Sep 24, 2020 5:28 pm

nickle15 wrote:Excellent points - thanks. When it comes to caps, do you think those are any higher quality today over what would have been used when the synth was new?

By the time synths came along they knew how to make good electrolytic capacitors. Whether the manufacturers used the good ones is a different matter but that also goes for capacitors today as there have been plenty of examples of short lived capacitors in more recent gear. Most people seem to recommend Panasonic or Nichicon 105 degree C rated replacements but they will still probably suffer from the same issues after 40 years - especially if the synth isn't used for a while.
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Re: Synth repair

Postby Folderol » Thu Sep 24, 2020 8:11 pm

Apart from random failures (which you'll always get) there was only one comparatively recent mass sort-term death of caps. This was due to a formula being stolen, but incomplete so the wrong electrolyte was used. I came across one as recently as about a year ago. They almost always have a dark green sleeve.

Even over the last 10 years performance and reliability has continued to improve, while the physical size continues to shrink - sometimes that's not an advantage! In particular, internal leakage (which all electrolytics suffer to some degree) has dropped like a stone, to the extent that you can now use them reliably in high impedance timing circuits, where previously only 'dry' types could be used.
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Re: Synth repair

Postby nathanscribe » Thu Sep 24, 2020 8:16 pm

What they said. And, conversely, there are plenty of 40 year old synths that have never been serviced and work just fine. For how long, is another matter! Caps do fail, and anything repeatedly stressed by heat is worth keeping an eye on I think. Old CMOS can fail in awkward ways. Switches, sliders, pots – they gunge up, and corrode, and wear out. An increasing number of parts are nigh on impossible to replace as they've been obsolete for many years and anything custom (Yamaha's own-brew ICs in the CS analogue, for example) are rare and very expensive when they do crop up.

A general rule of thumb for vintage synths is that at least half of the ones you've got will either not work at all or in the way you want, at any given time :D

They are great though.
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Re: Synth repair

Postby James Perrett » Thu Sep 24, 2020 10:02 pm

Folderol wrote:Apart from random failures (which you'll always get) there was only one comparatively recent mass sort-term death of caps. This was due to a formula being stolen, but incomplete so the wrong electrolyte was used. I came across one as recently as about a year ago. They almost always have a dark green sleeve.

I'm the owner of a 25 year old Fostex G24 - the only device I've owned that has needed mass capacitor replacement - all 600 of them! What is worse is all the gunk that has leaked onto the circuit board which causes all kinds of other problems. These were all early surface mount electrolytics in a package style that is no longer used.
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Re: Synth repair

Postby nickle15 » Fri Sep 25, 2020 1:58 am

Wow, thanks to all for the great insight. I really appreciate you sharing!
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Re: Synth repair

Postby Folderol » Fri Sep 25, 2020 8:21 am

James Perrett wrote:
Folderol wrote:Apart from random failures (which you'll always get) there was only one comparatively recent mass sort-term death of caps. This was due to a formula being stolen, but incomplete so the wrong electrolyte was used. I came across one as recently as about a year ago. They almost always have a dark green sleeve.

I'm the owner of a 25 year old Fostex G24 - the only device I've owned that has needed mass capacitor replacement - all 600 of them! What is worse is all the gunk that has leaked onto the circuit board which causes all kinds of other problems. These were all early surface mount electrolytics in a package style that is no longer used.
That's really weird. I've never come across that - mind you, I've mostly worked in industrial electronics. I've only had occasional SM ones dry out, along with occasional exploding ones (due to overvoltage faults) but no leakage at all. Curious, when doing a quick on-line search I see that it was quite a common problem with those machines, which rather suggests they were getting parts from dodgy Taiwanese suppliers.
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Re: Synth repair

Postby Arpangel » Sat Sep 26, 2020 3:08 pm

Some synths have proprietary IC's that are very difficult to find, if at all, the only reliable old synth I owned was a Juno 6, I had a horrible Prophet 5 that was impossible to fix, a "specialist" had numerous goes at it with no success. My ARP Odyssey was a nightmare, owing to having to find an encapsulated filter, once replaced it was never right again.
Old synths are a nightmare, you ever know what’s going to go wrong next.
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Re: Synth repair

Postby resistorman » Sun Sep 27, 2020 3:08 am

Arpangel wrote:Some synths have proprietary IC's that are very difficult to find, if at all, the only reliable old synth I owned was a Juno 6, I had a horrible Prophet 5 that was impossible to fix, a "specialist" had numerous goes at it with no success. My ARP Odyssey was a nightmare, owing to having to find an encapsulated filter, once replaced it was never right again.
Old synths are a nightmare, you ever know what’s going to go wrong next.

This is very true. A better project might be building a modern open source device together.
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