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Taking the Barn to Yamaha

Jim Coffey

Jim Coffey

Member
Howdy folks. Now that I seem to be headed in a Yamaha M-85 direction, I'm moving over here to learn what I can.....hopefully Yamaha pieces can actually grace my Barn:

https://audiokarma.org/forums/index...el-can-go-loud-too-but-always-precise.952847/

The M-85 has an appointment at the shop tomorrow morning where I will be witness to the opening. Now praying to the audio gods that we don't find anything to cease my Yamaha progress.

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Sweet!

If you're going to be using small speakers (per your other thread), be sure to keep the kiddo's away from the volume knob. ;)
 
Understood. At 26 years old my kid will get a destructive visit from me at his house if that knob gets abused at 6 feet high.
 
What a great time watching the shop throw the M-85 on the bench (not literally), hook it up to all the laboratory gadgets and watch it work! With very few exception the very good news is that every single thing works from idle to full bore. So cool the shop had all the M-85 specs on the PC screen in seconds, and all were in perfect spec as purchased. There are a few suspect solder joints and a few burned components on the board.....strange the amp had full performance. Got to 330WPC before clipping.....I think that's the term used. A bit dusty as expected and normal??? rust on the power supply? And on top of mine, starting to be remnants of the damping pads nowhere near as clean as the ones here.

Shop says the rust is no big deal as long as I don't accelerate it near a humid or corrosive environment. But I don't like the crispy old pads. I want to clean at least the tops and put some Dynamat on them or something. any thoughts or experiences here would be appreciated.

M-85 rusty power supplies.jpg


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The goofy speaker wire terminals were discussed, and recommended to me that they be replaced with a banana jack kit from Speaker-Terminal.com. Looks like $111.56 USD plus whatever tax and/or shipping and $100 shop install. Any thoughts or experiences here would also be appreciated. https://speaker-terminal.com/en/produkt/yamaha-m80-85-speaker-terminal/

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Saw this guy and his massive M-85 renovation. https://www.facebook.com/bkprecisio...-ended-up-replacing-all-outp/699202024012920/ That must have cost a few bucks!
 
One other thing....I guess my M-85 is not U.S. spec because it has adjustable voltage and what seems to me to be a tiny 120V power cord with no ground. Shop says no concern. Do some M-85's have a 3 conductor power cord with u-ground plug?
 
Yours has the silver heat sinks, then?

No problem to run with the original two conductor cable.

The speaker connections are a pain. If this is your forever amp, probably worth the cost of the upgrade.

Let us know what you think when it gets some music through it.
 
M-85's do not have ground pins. They, along with most audio from this time are floating ground. Ask your shop to look for corrosive glue under the two larger caps on the PCB. Not the big huge ones in the back, but the two biggest ones not retained by any brackets.
 
Are you going to be connecting and disconnecting speakers a lot? Then new terminals might be worth it. If you are going to install it and leave it in place for a long time I wouldn't spend the money on it.
 
The OEM speaker terminals are a weak spot, so be careful. That's probably why there are replacement kits, or at least one of the bigger reasons, is that they get broken a lot. Too good of an amp to let a broken speaker terminal keep it down.
 
Burned components???

Rusty transformer is no big deal IMO. Foam on the transformers is remove and don't replace IMO, Others may have different opinions.
 
Yes I have the silver sinks. By the other picture from the web I assume some came in black. Good to go on the floating ground if they're all that way. Will ask the shop to check further for that glue spot.

Standing by for other opinions on the transformer pads.....maybe I just love Dynamat and need an excuse.

Thanks for the replies and thoughts so far guys!
 
Jim Coffey said:
Yes I have the silver sinks. By the other picture from the web I assume some came in black. Good to go on the floating ground if they're all that way. Will ask the shop to check further for that glue spot.

Standing by for other opinions on the transformer pads.....maybe I just love Dynamat and need an excuse.

Thanks for the replies and thoughts so far guys!
Click to expand...
:lurk:
 
Tell us about dynamat. I thought it was sound proofing.

By all means, get rid of the crumbly foam. Lead the way for us on what to replace it with. I was just going to remove it and deal with transformer hum should it appear.
 
Just off the phone with an engineer at Dynamat. He thinks their Xtreme damping material would be an excellent replacement for the foam if Yamaha did intend it to deal with resonance/vibration. 100% effective up to 140 degrees, and a second layer stacked is only 50% effective so two pieces stacked are not twice as good as one.

https://www.dynamat.com/products/dynamat-xtreme/?tab=automotive

Yes Dynamat makes many other products including soundproofing. Unfortunately a little costly, but not much needed in an amplifier. Lesser cost competing products all over the market, but I've never rolled that dice. Think I'm going to do this 2021 technology to replace Yamaha's great but 1980's technology. I guess why Yamaha and some of the others are what they are that they did things like this in those days.
 
That foam was a bad idea from the get go. IMHO The power transformer put out more heat than the heatsinks do. The foam just held the heat from the transformers. I remove the disintegrating foam and give the transformers either a coat of paint or cover them with adhesive foil either aluminum or copper.
 
Oh BTW.. Trivia : The M-80/85 is not a dual mono design like some people think. Just because of two power transformers. One transformer supplies power for the positive rails and the other for the negative rails. So both transformers supply power for both channels.;)
 
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