Vintage Synth Repair

My beautiful Quadra came out of storage after 6 years and it's got problems. Everything worked fine when it went into storage, but now when I turn it on, it produces no sound after a few minutes.  I am pretty good at mechanical repairs, but have never attempted electronic repairs.  I would love to tackle this myself rather than take it to a shop.  Any idea what I could look at first?

Thanks, all!

Jeff

First I'd look at PSU, check if all voltages are on spec values, and  
probably change all electrolytic capacitors.

Daniel Forro

On 2 Mar, 2013, at 8:41 AM, stargazer052070 wrote:

> My beautiful Quadra came out of storage after 6 years and it's got  
> problems. Everything worked fine when it went into storage, but now  
> when I turn it on, it produces no sound after a few minutes.  I am  
> pretty good at mechanical repairs, but have never attempted  
> electronic repairs.  I would love to tackle this myself rather than  
> take it to a shop.  Any idea what I could look at first?
>
> Thanks, all!
>
> Jeff

NO offense to DIY people but if you dont know basic electronics and proper soldering and inspection, SEND your unit to someone who DOES.

I've been in design and test my whole adult life ( 30+ yrs)

I've seen what well-intentioned people have tried to fix.

I just worked on a TR-909. The person that did the mods should have stayed away from it.

I own mine OWN service and repair here in Vermont and see plenty of retro keys and rhythm units.

The Quadra is full of connectors and ribbon cables that may have oxidized. The case is pretty flexible too and there's this big connector board that spans a bunch of the other boards which is hard to seat right across all the points it needs to span. You might reseat all connectors but you could also do a lot of damage in there too. Quadras are selling for quite a bunch at the moment and one of mine is a parts machine mainly because I tried to fix it myself and plugged a connector in backwards, sending voltages where they should not go. Think about it.
   PT

From: stargazer052070 <stargazer052070@...>
To: vintagesynthrepair@yahoogroups.com 
Sent: Friday, March 1, 2013 3:41 PM
Subject: [vintagesynthrepair] arp quadra sound quits

  
My beautiful Quadra came out of storage after 6 years and it's got problems. Everything worked fine when it went into storage, but now when I turn it on, it produces no sound after a few minutes. I am pretty good at mechanical repairs, but have never attempted electronic repairs. I would love to tackle this myself rather than take it to a shop. Any idea what I could look at first?

Thanks, all!

Jeff

Do not learn how on a quadra, it is immensely odd and complex.  This is
exactly the sort of job you shouldn't start with no experience.

What you need is a really good experienced tech.  It might be simple, but
you neede that experience to trace the problem down,  If you want to
practice 

desoldering you will melt traces, put things in backwards, damage componets
and fragile connectors, connect things backwards (really easy with older arp
gear), etc.  

 

Do not get me wrong I always encourage DIY but this is like starting brain
sugery with an intro to anatomy guidebook, just don't do it.

If you love the synth get it to a tech, $300 and you might have the baby
running.  What region are you in?  We'll find you a solid tech.

 

Lorne in canada

--- In vintagesynthrepair@yahoogroups.com, "stargazer052070" <stargazer052070@...> wrote:
>
> My beautiful Quadra came out of storage after 6 years and it's got problems. Everything worked fine when it went into storage, but now when I turn it on, it produces no sound after a few minutes.  I am pretty good at mechanical repairs, but have never attempted electronic repairs.  I would love to tackle this myself rather than take it to a shop.  Any idea what I could look at first?
> 
> Thanks, all!
> 
> Jeff
>

If there is no sound at all from any of the four sections, nor any of the several outputs, it does suggest power supply. I am having a similar issue, where I have to cycle the power to get a consitent output, and I'm guessing I need to rebuild the PSU.

I had a similar problem a few years ago, (no sound at all) and it was a capacitor in the power supply. +1 to the above though, there is this funky ribbon connector that connects the microprocessor to the main board, I have no idea how to replace that if broken, and the inside is frighteningly complex. I know my limits.   If you are lucky enough to own a Quadra, unless you're compfortable DIY, have someone else. For a rare and expensive box, it is worth it. And yes the battery (damnit I need to check that) just saves the program memory. 

NOTE, I've been told the battery can be replaced wiht the lithium coins for longer life (and no battery leakage.)