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I recapped my M-65 and have a few questions.

N

nodak

New Member
Its my first post here and first off I'd like to thank you all. Ive been reading this subforum on and off for years and it gave me the confidence to take on a project like this. It went off without a hitch and the difference in sound was immediately apparent.

My first question is where can I download the service manual? Yes I did this without a manual. I bought a pack of caps off ebay from some guy in Canada and just switched them out two at a time and then turned it on. I figured that as long as the cap didn't blow and the protection circuit didn't click on I was doing fine. Hifiengine isnt taking new accounts so no luck there. The ones that are available are unreadable and missing pages. The reason I ask is there are a few resistors that have corrosion from the glue and I'm gonna swap them out and just want to double check that Im getting the right stuff.

Second question, Is it worth it replacing those big caps in the back? I know there aren't any drop in replacements but if recapping all the little ones made this much difference Im thinking that those big ones need to be replaced too?

Is there anything else I should do next time I open this up?



Im so stoked, I think this amp sounds better now than when I got it 5 years ago.
 
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nodak said:
My first question is where can I download the service manual?
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Contact Norman at Analogalley.com..For better than original HQ scan...

https://www.analogalley.com/osccart...d=672&osCsid=8bfb793604e497ba826a97213243b69f
nodak said:
I know there aren't any drop in replacements
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Yes there is ..kind of.. get 4 of these.
https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/383LX333M050B052VS?qs=fupM46RXT63NsdfycDrUwA==

And a roll of 1/4" wide solder wicking...

https://www.mouser.com/ProductDetail/Techspray/1813-5F?qs=MUyZ%2BuhSCNWWUFSWAqqq/Q==
 
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nodak said:
The reason I ask is there are a few resistors that have corrosion from the glue and I'm gonna swap them out and just want to double check that Im getting the right stuff.
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Probably some diodes and possibly transistor leads as well . Even jumper wires get slathered with that damn glue.
 
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IMG_20230426_165421291

  • Media owner nodak
  • Date added
Yamaha M-65 corrosion
This is the extent of the corrosion. When I said a few I should have said 1. I guess I got lucky considering what one would expect.

I think these two are R141 and R142 in the m-60 service manual from the link above, it isn't printed on the board. I have the 4 caps you linked in my cart once I figure out a good replacement for this pair of resistors I'll put in my order.

I dont know how I missed those capacitors, Ive been reading here for a while, are they new?

Also, I already have a roll of 1/8" solder wicking for some reason. Would this suffice or should I just spend the 6 bucks on the 1/4"?

Thanks Avionic. Ive been reading your posts in this sub forum for years and believe it or not I owe some of my being able to pull this off to you. I feels like I owe you a beer or something.
 
There's a freebie service manual at elektrotanya.com that's ok, kinda grainy but better than any free M60 SM.

I leave the main filter caps alone but am curious as well.

Replace resistors R141 & R142 asap. 22ohm , 1/4 watt flameproof 5% tolerance or less.
Right next to those...clean, re-tin, or replace jumpers J219,220,221

If you want to replace the 3 incandescent meter lamps with LED's I found a great recipe on the cheap...just ask.
Good job, glad to see folks service these before they fail from glue. Let us keep the original transistors holy. :beerchug:
 
Soundscape said:
There's a freebie service manual at elektrotanya.com that's ok, kinda grainy but better than any free M60 SM.

I leave the main filter caps alone but am curious as well.

Replace resistors R141 & R142 asap. 22ohm , 1/4 watt flameproof 5% tolerance or less.
Right next to those...clean, re-tin, or replace jumpers J219,220,221

If you want to replace the 3 incandescent meter lamps with LED's I found a great recipe on the cheap...just ask.
Good job, glad to see folks service these before they fail from glue. Let us keep the original transistors holy. :beerchug:
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Thanks you, that service manual is much better than anything that else that I have found.

Im gonna change the filter caps, I have to know if it will make a difference. My amp sounded good after it warmed up and you pumped some watts through it, but the difference in quality was shocking after changing the caps. My kids even commented on it and they are audio snobs. I got used to a failing amp and I have to know what changing the filter caps does or doesn't do.

When I open this back up I will hunt and find those J's, thanks for the advice.

Thanks for the compliment. This is the first time I've ever done this, but to replace it with something just as capable is a tall order. Its better to try and fail fixing it than settling for something substandard.
 
nodak said:
Im gonna change the filter caps, I have to know if it will make a difference
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I want to know as well. What you discover will answer some burning questions I've had on this piece. For reasons I'll share later.
Ain't it rewarding dude?! I notice a 40% sound quality increase on every amp that's been re-capped. I believe power amp re-caps are great starter pieces for newbies cuz there's only 18 on this main board not including the big ass main caps, and 8 on the meter board. Pre-amps & receivers are a re-cap nightmare with higher fail rates from mistakes.

The 2 resistors I cautioned you about are time bombs brother. They are important in the circuit. They see a tidal wave of energy surge upon power up. Look at the corrosion at the bottom of them. I wouldn't even turn it on again without replacing them. Notice they are also an offset height from the board, raised a 1/4 inch from the board. Follow suit with the replacements please.Definitely shy away from the class A button in the interim.

Your kids will still be enjoying that fine piece decades from now from what you've done today.

Good stuff, salute
 
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Soundscape said:
18 on this main board not including the big ass main caps, and 8 on the meter board.
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I counted up the caps I replaced and came up with 29

Soundscape said:
I want to know as well. What you discover will answer some burning questions I've had on this piece. For reasons I'll share later.
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I have just the songs for this too, ones that demand huge spikes in dynamic rage. I'm definitely gonna do a before and after test.

Soundscape said:
Pre-amps & receivers are a re-cap nightmare with higher fail rates from mistakes.
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I did see how much bigger of a job they are. There is so much room for mistakes. This amplifier was straight forward and really easy to work on.
 
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nodak said:
Its better to try and fail fixing it than settling for something substandard
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Well said...hence the myriad of membership here :beerchug:

nodak said:
OK Im gonna show my lack of knowledge but I came up with 18 Ohms on the resistor I posted. Where did I go wrong reading the colors?
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You didn't go wrong. Amazed you can make sense of the colors from the heat, time, and glue ****. Fused resistors can drift from age so I've heard. It's a 22ohm .

nodak said:
I counted up the caps I replaced and came up with 29
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Thought it was 28 (from memory). You're probably right since ya just did it

nodak said:
This amplifier was straight forward and really easy to work on.
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It's my favorite for all those reasons and more. I drive two of these with a C-80 control amp while my M-80 just sits like a cuck.
 
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nodak said:
Well I read up on resistors and it seems that this would be a good choice for a replacement?

https://www.mouser.com/ProductDetail/Vishay-Dale/RN60D22R0FB14?qs=f94C5MEAK/T6tgPDrMIvJQ==
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That's pretty good but it's not flame proof or fusible. That resistor on the print has one of those "use exact replacement" symbols next to it.
This is the best one I can find so far:

https://www.mouser.com/ProductDetail/TE-Connectivity-Holsworthy/FRN25J22R?qs=DfH2yQaBz6s2/T1FPEbNPA==
 
Soundscape said:
That's pretty good but it's not flame proof or fusible.
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The Vishays are " flame retardent epoxy coated" means they will smoke alot but no flames. Note : I've had issues with the TE's not handling the " power on" surge in this app.
 
avionic said:
The Vishays are " flame retardent epoxy coated" means they will smoke alot but no flames. Note : I've had issues with the TE's not handling the " power on" surge in this app.
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Good to know, thank you . :thumbsup: I get frustrated trying to find replacements for the cautionary note resistors.
 
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