50 year old amps

[audio_PHIL_e]

It tends to be caps in the power department that are the ones to watch.

IMO this is right, they do seem to be the ones under the most stress, which could take other components with them if they fail. Whereas cathode bypass caps could leave your pride & joy sounding a lot worse but might leave other components intact.

 

[hiesteem]

Seems to be pros and cons to all approaches. Indeed a lottery.

Twist and risk unnecessary expense, and perhaps worse sound.

Or twist and avoid risk of a cap popping,

Stick and the chances of a cap going pop increase.

Or stick and save money, and retain the original sound.

Thanks for all the useful replies all.

I do my best to research anything I am going to spend money on. Life experience has taught me this. The guy I used took the time to assess and evaluate component options. He would ring me and discuss which way to go. He sourced some of the original parts from Poland and talked me through the process, which was lengthy. Eight months actually. The better engineers are busy and you have to wait for them until they get around to your amp.
Often it's the small caps that wear and cause problems along the chain. My engineer would fix a channel at a time, following the path and testing along the way.
Ultimately it depends on the quality of the amp and your personal needs, but with a real quality older amp that we are talking about, I say 100% get it repaired.
These amps are not going to be bettered without careful consideration and ££££ .
I am happy to give you the details of the guy I used, should the need arise in the future.
However expect to have to wait, once he has it, but be safe in the knowledge that he is excellent at this.

 

[bigrod]

I have a Pioneer SA706 from 1978 . I hadn’t run it for maybe 30+ years . I knew one of the VU bulbs was out and Des “HAPHAZARD “ told me where to get some from .. when they arrived I took the amp to a guy who specialises in mid 70s/ 80s Japanese gear .. I told him to check it out while putting 2 bulbs in ..
His comments where ,, what’s in there is as good as they get ,, did a few tests and said not to replace anything
after 40+ years it still sounds sweet . Decent phono stage too .
In fact most Japanese integrated of that era did have good phono stages , mainly because that was the best source .

 

[dave]

I am quite reluctant to re cap anything, and the thought of recapping all my gear every 10 years is ridiculous and utterly soul destroying. May be a British thing, being a bit cooler here than in the state's, but neve seemed like much of a.problem. However some brands of capacitor are know to be unreliable, some German and American in my limited experience and these should be dealt with.

I have a Revox B710, which has numerous peculiar faults, I bought a recap kit, and have done most of it, and it is mostly come back to life. Likewise swapping out an intermittent PSU cap in my Telefunken RC300, has restored it to reliability. There is also the risk of a cock up. Destroying the PCB, reversed polarity or fitting wrong values is a real possibility and risk.

Apart from that in my experience of 30 years of tinkering, one PSU cap has failed in one of my QUAD IIs.
On the other hand I had a rather nicotine stained Luxman L85v, that worked fine, completely original, and my huge early 90's Sony amp is fine apart from noisy switches.

How we fare in the future with possibly dubious quality Chinese caps, I guess we will find out, but I for one ame going to try and source quality Japanese HT caps for any future valve amp builds, much as I love my nice eBay probably fake Nichicons...

 

[rabski]

There is also the risk of a cock up. Destroying the PCB, reversed polarity or fitting wrong values is a real possibility and risk.

Very much so. Not helped also by the fact that an awful lot of PCBs are incorrectly marked. I've seen that so many times that I've put my conspiracy theory hat on to wonder if it isn't done deliberately to bring business into 'certified' repairers in some markets.

Always make your own markings or drawings. Fit replacements exactly in line with what comes out, and never rely on PCB print as to where things go, what values and which way round.

 

[Juancho]

Very much so. Not helped also by the fact that an awful lot of PCBs are incorrectly marked. I've seen that so many times that I've put my conspiracy theory hat on to wonder if it isn't done deliberately to bring business into 'certified' repairers in some markets.

Always make your own markings or drawings. Fit replacements exactly in line with what comes out, and never rely on PCB print as to where things go, what values and which way round.

+1 I always take a photo. Quickest way to make sure polarity, + - etc are correctly re-done!

 

[bigrod]

Very much so. Not helped also by the fact that an awful lot of PCBs are incorrectly marked. I've seen that so many times that I've put my conspiracy theory hat on to wonder if it isn't done deliberately to bring business into 'certified' repairers in some markets.

Always make your own markings or drawings. Fit replacements exactly in line with what comes out, and never rely on PCB print as to where things go, what values and which way round.

Very much like owning a new BMW
Without the proper codes you can’t take it to your local garage ..
Diane’s car has a warning light come on , can’t get it into BMW till 30th December. And if she needs a courtesy car it will be February.. the local garage who services my car and did Diane’s Jaguar can’t access any of the electronics ..
I thought all this had been stopped??