I have an early quad 34 pre amp serial 6183
I'm going to see an old guy today who has most parts needed to build anything in his workshop, My 34 is quieter on the left channel and also has some popping and static.
It has never had anything done to it since new what would be the obvious parts that would need replacing and does anyone have a upgrade pdf or service walk though they can point me too please.
I also have the 303 might take it with me if anyone could point me in the right direction with that too.
Thanks
Chris
I'm going to see an old guy today who has most parts needed to build anything in his workshop, My 34 is quieter on the left channel and also has some popping and static.
It has never had anything done to it since new what would be the obvious parts that would need replacing and does anyone have a upgrade pdf or service walk though they can point me too please.
I also have the 303 might take it with me if anyone could point me in the right direction with that too.
Thanks
Chris
Advice would be locate the initial fault by measurement and diagnosis rather than just think of replacing parts.
Noise, popping and static will show instantly on a scope and so it should be straightforward to at least locate the general area causing the problem.
Capacitors are obvious favourites to replace and I believe the Quad uses tantalums in a few locations.
I wouldn't just replace in hope. Find the problem first, then think of replacing older parts.
The 303, definitely small cap replacement (electrolytics). I recall these used ROE brand which I have had issues with on the 303.
Noise, popping and static will show instantly on a scope and so it should be straightforward to at least locate the general area causing the problem.
Capacitors are obvious favourites to replace and I believe the Quad uses tantalums in a few locations.
I wouldn't just replace in hope. Find the problem first, then think of replacing older parts.
The 303, definitely small cap replacement (electrolytics). I recall these used ROE brand which I have had issues with on the 303.
Switches and pots can also get tired enough in old gear to become erratic and noisy. Deoxit (Cramolin) contact cleaner treatment should revamp them if they are part of the problem or even the main culprit. For Quad service manuals try the well known audio gear library site HiFi Engine
Balance control some time break down.
Can be fix with some glue and melt plasticitet parts with the solder.
I have done it on two 34 with the same problem.
Can be fix with some glue and melt plasticitet parts with the solder.
I have done it on two 34 with the same problem.
Capacitors are the main fault I've seen and read about here, for both the 303 amplifier and the 34 preamp. Also, as Speak points out, the 34 can have a very nasty problem with those unique tone/balance switches breaking up. My advice is don't play with them - set gently and forget, unless you want an unusable device needing a really difficult reconstruction/repair job that no professional service person would take on without the spare time and $$ incentive.
A common fault that you'll read about in several previous 34 repair threads here, is that some electrolytic caps have a tendency to leak through their PCB holes then corrode the copper tracks on the underside. This leads to loss of output as well as noise. If it has occurred, it's at least visible and an easy first check before touching or spending anything. If you buy replacement parts, go to authorized sellers with a reputation to protect - not the typical dodgy Ebay store which simply vanishes, changes identity or drops lines when there are problems with their cheapo and often fake products.
With any repair, you need to use the service manual schematic to check what it is you are looking at before blindly following some guide to fixing likely non-existent faults. I find that repair guides are only useful after you find the faults, because they suggest what might be wrong in general or by anecdote but if you want to DIY, you really need to learn how to find any problems in your gear systematically.
A lot a people take a shotgun approach to repairs when they don't understand electronic circuits nor how to use simple instruments like a multimeter to help pinpoint a problem. It works for some but when the parts are unique or unobtanium after 30-50 years since manufacture, you will be wasting your time and money by needlessly replacing the common, garden variety components that seldom break down, whilst the serious problems may remain untreated.
A common fault that you'll read about in several previous 34 repair threads here, is that some electrolytic caps have a tendency to leak through their PCB holes then corrode the copper tracks on the underside. This leads to loss of output as well as noise. If it has occurred, it's at least visible and an easy first check before touching or spending anything. If you buy replacement parts, go to authorized sellers with a reputation to protect - not the typical dodgy Ebay store which simply vanishes, changes identity or drops lines when there are problems with their cheapo and often fake products.
With any repair, you need to use the service manual schematic to check what it is you are looking at before blindly following some guide to fixing likely non-existent faults. I find that repair guides are only useful after you find the faults, because they suggest what might be wrong in general or by anecdote but if you want to DIY, you really need to learn how to find any problems in your gear systematically.
A lot a people take a shotgun approach to repairs when they don't understand electronic circuits nor how to use simple instruments like a multimeter to help pinpoint a problem. It works for some but when the parts are unique or unobtanium after 30-50 years since manufacture, you will be wasting your time and money by needlessly replacing the common, garden variety components that seldom break down, whilst the serious problems may remain untreated.
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