M-85 how to questions...

babeba67

Active Member
Hey gang,

My M-85 was making a low level hum so I took it into the local shop that has done repairs for me in the past. They replaced some caps, soldered some joints, etc. and it came back sounding great.

1 thing I forgot to mention to them when I dropped it off was the 3 buttons on the front that are labeled 2ohm, 4ohm, 8ohm for the lighted display when depressed. Each of these pushes in and out just fine but the meter levels don't change. I assume it's "stuck" on one of the settings (guessing 4ohm by the output level) but not sure. So, how does one go about fixing this?

2nd thing I noticed, I hooked this amp up to a yammy pre amp and ran 1 pair of speakers first on channel B then on C with no issues. However, when I hooked it up to channel A the left channel does not seem to beworking for whatever reason. Checked all external connection and all seems good. Any ideas there?

Thanks!
 
when I hooked it up to channel A the left channel does not seem to beworking for whatever reason.
Protect relay contacts fouled on RY101 or dirty speaker selection switch contacts.
 
Last edited:
I assume it's "stuck" on one of the settings (guessing 4ohm by the output level) but not sure. So, how does one go about fixing this?

Replace the switch assemblie(s).Disassemble the assemblies and try to fix the switch(s).
 
Could also be broken solder connection on the relay/speaker binding post circuit board or even a cracked board..A very common problem especially if the big ass crappy binding posts have taken and impact.

: additional to post #2
 
Last edited:
1 thing I forgot to mention to them when I dropped it off was the 3 buttons on the front that are labeled 2ohm, 4ohm, 8ohm for the lighted display when depressed. Each of these pushes in and out just fine but the meter levels don't change. I assume it's "stuck" on one of the settings (guessing 4ohm by the output level) but not sure. So, how does one go about fixing this?

Replace the switch assemblie(s).Disassemble the assemblies and try to fix the switch(s).

I believe they are also for the display only, no effect on output or anything else.
 
Back
Top Bottom