Nick Danger's Yamaha M80 Amplifier Repair/ Restoration

[brutal]

It's alive and well.

PS voltages are good. Bias voltages are good.

The only issue I cannot correct is the Class-A bias is higher on one channel than the other by about 10mV (107mV/95mV). Class A/B they are both dialed in @15.5mV.

It's done except I still want to pull the faceplate and recap the half dozen 'lytics that are on the meter PCB.

 

[brutal]

Is done.

Give me a ring if you still have my number. Otherwise send me a PM here and/or on AK.

 

[Lastplace]

Nice Job, I love my M & C-80 set up.

 

[Nick Danger]

Cheers, Russ! Appreciate your help on this one and will give you a call in the next day or so. Maybe I can swing by next week when I am in your neck of the woods and we can shoot the breeze.

 

[brutal]

teaser pics

 

[NavLinear]

teaser pics

Nice work Russ! I'd post some teaser photos butt we'd be way off topic.

 

[Nick Danger]

Now we just have to find a source that can repro the giant caps and I will be good to go for a lifetime.

 

[Nick Danger]

teaser pics

View attachment 19853 View attachment 19854 View attachment 19852 View attachment 19851 View attachment 19856

Crazy how quickly the copper oxidizes- I cleaned them a few months ago during the initial teardown!

 

[laatsch55]

It's that nasty Denver air.....don't happen up here....

 

[Nick Danger]

So much for the "clean mountain air".....

 

[orange]

It's all of the neighbors

 

[brutal]

Crazy how quickly the copper oxidizes- I cleaned them a few months ago during the initial teardown!

What kind of solder are you using?

There seemed to be an excess amount of residual flux. I also cleaned all the crevices well and cleaned the through hole in the PCB before reassembly. One of the pulled transistors also had lots of flux on two legs.

I probably should have it the bus bars with the lacquer spray like I've done for others, but didn't think about it before reinstalling them. I think they'll be OK now.

 

[brutal]

It's all of the neighbors legal weed

FIFY

 

[Nick Danger]

What kind of solder are you using?

There seemed to be an excess amount of residual flux. I also cleaned all the crevices well and cleaned the through hole in the PCB before reassembly. One of the pulled transistors also had lots of flux on two legs.

I probably should have it the bus bars with the lacquer spray like I've done for others, but didn't think about it before reinstalling them. I think they'll be OK now.

Kester with some paste flux.

 

[Northwinds]

Man, I remember dropping off a blown up M-80 at a local auction a few years ago. Found it and the matching preamp in a damp cellar. Both powered up but neither worked. Good to see your getting your monster back Doug

 

[Nick Danger]

Cheers, Ron. Perfect timing, too as I noticed a hum comin' from my WOPL's power supply today and it will need to be pulled from the system to figure out the issue.

 

[laatsch55]

Heard through the speakers?

 

[Nick Danger]

Nope, just the amp itself.

 

[laatsch55]

An audible vibration from the chassis?

 

[Northwinds]

I have a low frequency hum also but I can't do anything about it since this is my main amp. I only hear it when a source is not playing and it does not get any louder with volume increase. I only hear it in the speakers, not the chassis. I am wondering if the fault is in the nest of wires in back of my stand so I can't fault the amp yet