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Post-Recap: What follows?

davstev

davstev

Well-Known Member
So, recapping. It's often advised for old gear, for obvious reasons.

I've done it before, to varying results, mostly good. I am good with the careful selection and replacement of caps, but I lack the knowledge of the principles of electrical circuitry and amplification that will ensure that I get the very best of my recap, by following up with the fine-tuning. Presently considering recap of a Sansui Eight receiver.

Are there any threads here or general advice for knowing what adjustments, and in what order, we should check after a recap?

As a couple of examples, I know that measuring and adjusting bias, and measuring DC offset at speaker terminals, are important.

Does it vary from amp to amp, receiver to receiver, in terms of what should be checked? Not the values themselves, but just the things that need checking/adjusting, and the sequence in which they should be done?

Some may say, "just hand it over to a good tech", but If I can learn and do all of this myself, that would be great.

Any advice or guidance is appreciated.
 
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only four steps left.

one - follow the service manual's guide for any final adjustments (plus any advice you find on the audio forums
for identical and similar models - eg - the family).

two - make sure ALL your connections are safe - no dangling single threads of speaker wire, speaker
plugs that are never closer together than speaker terminal posts (to prevent those dangling banana
plugs from touching each other and then shorting the outputs together when your cats jump on them).
accidental speaker shorts are probably the leading cause of amplifier damage. if necessary and
do-able, use ring connectors like on cars - I wonder why? do both ends and both channels.

three. burn in. either put a dummy load or use cheap speakers. do not play them at live concert levels
(100+ DBs like within 100 yards of a 747 on take-off) - you may BLOW your unit while out of the room
and possibly set your residence on fire. do not listen to the burn-in deniers while they're temporarily
on climate change denying. ensure your unit exercises the various signal functions so you know they
all work.

four - enjoy the music.
 
Standard advice for conventional Class A or AB amplifiers is to follow the manufacturer's service manual instructions to set idle current and DC offset.
 
Bob said:
do not listen to the burn-in deniers while they're temporarily
on climate change denying.
Click to expand...
?

"Burn-in" is a standard process with electronics manufacturing and repair to identify manufacturing or assembly flaws when the unit is first run. Most failures, if they're going to occur at all, will occur within the first 24 hours. Burn-in helps catch such failures before the unit is sent to a customer.

It should be distinguished from "burn-in" as a permanent audible improvement that allegedly occurs with certain electronic components, audio devices, and interconnects or speaker leads. That is controversial, scientifically unconfirmed, and largely unrelated.
 
davstev said:
Is bias and idle current the same thing? (Just learning here.)
Click to expand...

Yes. Bias current is the amount it's biased (offset) from zero, when no signal is playing. The intention of bias, is to keep the transistors a little bit "on", so that the non-linear transition from hard off to on is avoided.
 
maxhifi said:
Yes. Bias current is the amount it's biased (offset) from zero, when no signal is playing. The intention of bias, is to keep the transistors a little bit "on", so that the non-linear transition from hard off to on is avoided.
Click to expand...

Great info, thanks.
 
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