Nick Danger's Yamaha M80 Amplifier Repair/ Restoration

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.
 
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.
 
Now we just have to find a source that can repro the giant caps and I will be good to go for a lifetime.
 
It's all of the neighbors :smokin::geek:
 
Nick Danger said:
Crazy how quickly the copper oxidizes- I cleaned them a few months ago during the initial teardown!
Click to expand...

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.
 
Last edited:
brutal said:
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.
Click to expand...

Kester with some paste flux.
 
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
 
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.:wink:
 
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
 
You must log in or register to reply here.
Back
Top