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Yamaha M-60 amp restoration planning

Brad1234

Brad1234

Active Member
I have a working M-60 amp that I am planning to do a full recap of all electrolytics and looking for guidance on any other parts I should replace or test for best reliability long-term? I will replace the relay and trimmers as well. All of the corrosive glue has been removed and all of the parts affected by it are still in spec, but will be replaced anyway, just 2 1000uf caps and 2 22ohm resistors were damaged a little.

I have read thru the other posts on this model and nothing jumped out as being recommended to replace other than the electrolytics, but this unit is now 40 yrs old and wanted to get a current reading from the experts on it before ordering all of the parts. I have a lot invested already since I did bite the bullet on the (4) 33,000 uf/50v CDM 383LX main caps already. Any help will be much appreciated!

Is there a trick to getting the wire harnesses unseated from the board, they seem to be seated in there pretty good and I tried pinching them in various ways to release them with no luck. Attached are some pics of the amp.
 

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Probably an obvious one but I always replace any electrolytic of 1uf or below with polys. They'll never dry out and may sound better if in the signal path.
 
First....

Is the amp working?

If not fix it first.

Reflow every solder joint , with it working or not.

Then use it for a week or two to make sure its all ok and to fix any other
issues with it.

Then proceed with the restoration.

Athanasios
 
I'd be tempted to test or replace the 6 volt zener diodes, D113 D114, D117 D118. I'd replace the 3 center panel light bulbs too.
I'd service the relay before replacing that particular Matsushita. Old ones are high quality, I believe the contacts are silver. Up to you of course, I'm the minority opinion on this.
 
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Nashou66 said:
First....

Is the amp working?

If not fix it first.

Reflow every solder joint , with it working or not.

Then use it for a week or two to make sure its all ok and to fix any other
issues with it.

Then proceed with the restoration.

Athanasios
Click to expand...
The amp is working after cleaning off all of the glue and reinstalling the parts. I got the amp in a "not working" condition but never fired it up until I cleaned all the glue and checked affected parts. They were all still good and I put them back and fired it up slowly on variac and DBT and it works fine, bias set and holding steady for hours of play on mains. I don't plan to use it anymore until I at least recap it and check any other potential problem issues.
 
satpaul said:
Here is a recap of M65 but it is similar. But first get it running then continue. Pavel
Click to expand...
Thanks! I will check out that post, I did read the M65 is identical to the M60, except I think it has a meter shut off switch. My amp is working fine currently, just want to recap the 40 yr old electrolytics before playing it much. It has been in storage for years I was told from previous owner.
 
DatunWalnut said:
Probably an obvious one but I always replace any electrolytic of 1uf or below with polys. They'll never dry out and may sound better if in the signal path.
Click to expand...
I also use polypropylene Panasonics for everything 1uf and below on my restores. This amp just has a 0.47uf electrolytic below 10uf, so that one obviously can't be an electrolytic anymore.
 
Soundscape said:
I'd be tempted to test or replace the 6 volt zener diodes, D113 D114, D117 D118. I'd replace the 3 center panel light bulbs too.
I'd service the relay before replacing that particular Matsushita. Old ones are high quality, I believe the contacts are silver. Up to you of course, I'm the minority opinion on this.
Click to expand...
The low volt zeners are definitely suspect. With the cost of diodes it is easiest just to swap them after 40 yrs of use.
 
Any browning/heat signature on the board around TR111 and TR112 pre-drivers?

Brown stain Jones
 
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Brad1234 said:
but will be replaced anyway, just 2 1000uf caps an
Click to expand...
Fun fact...there's no exact replacements for these regarding lead spacing last I checked. But, there are some spare unused 7.5mm-8mm holes stashed under the original caps for new ones. C157,C158. I tried general purpose caps in this location before but it sounded like ass. Recommend audio grade there.

I won't be the guy recommending speaker post swaps. But someone will.

Non ferrous signal path Jones
 
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I put KW's in the 4th M-60 serviced last April. Sounded really nice and fit the cram holes well. KW's felt solid instead of that big hollow can kinda feel. They felt hefty like Chemicon KYB's but didn't sound like ass. Win win.

Ooh ooh, gotta know what's gonna replace the 5 Black gate caps in the signal path? All boned up here!
 
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