Looking at a Yamaha M-80 today.

whitrzac

Active Member
A local has a yamaha m-80 amp for sale, is there anything in particular I should watch for? It looks to be in decent condition, nothing out of the ordinary from the pics, one of the speaker terminals are fubar, and the meter lights don't work

I have a m45, m55, and m65(dead) already...
 
For serial over 11051 use the M-85 adjustment procedure and parameters. Over serial number 11051 the M-80 is identical to the M-85 except for the front and rear panel lettering.

what he is also saying is that if you would need to make the required changes according to M-80 service bulletins for serial numbers lower than 11051....OR.....the lower serial number will need "more" work, additional to: Watch for cold solder joints, remove Sony glue, old caps, speaker relays etc....and in your case remove and replace the speaker posts.

If you browse the linked thread above you will find plenty more info..

Edit:
http://audiokarma.org/forums/index....ervicing-a-yamaha-m80-85.591887/#post-9998386
 
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Make sure it fires up.
Test it to see if output is about the same on each channel, gain controls work about the same.

Be prepared to throw a few dollars at It to get it repaired/glue cleaned up/upgraded.
 
I picked it up for $120. They guy said he tested it before listing and it was on ebay as working.

Protection light is on. It dims when auto a is off and goes out when the range button is pushed in.

Something is screwy. Ill look into it more when i get home.
 
I picked it up for $120. They guy said he tested it before listing and it was on ebay as working.

Protection light is on. It dims when auto a is off and goes out when the range button is pushed in.

Something is screwy. Ill look into it more when i get home.
That is probably going to be and easy fix. If the problem is on the display board. Pull the front panel and verify that the 4 plug-in connectors are plugged in.
 

I know a guy that will walk you through the repair if you want to take on that task.
I've worked on it with avionic's help before. At the time it wasn't worth the $$$ in parts to fix it.

I gave it a quick onceover. The corrosive glue strikes again.
20161029_215535_zpstxkp3o9g.jpg

20161029_215526_zpsrejoxrrm.jpg


Smells like a fishtank/pond too...
 
what you see on the back is old solder flux and not the Sony glue. Sony glue will most likely be on the component side of the board. That said, I do see that it needs a second once-over :) for those solder joints. I see a few suspicious ones without even looking too hard.
 
what you see on the back is old solder flux and not the Sony glue.
I see corrosive glue damage.Especially on the second photo. It starts on the topside and over time corrodes through the lead to the solder connection.When it gets that bad it usually damages the solder pad as well.
 
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Top photo is a 3.9KΩ 2 watt metal oxide resistor.(R226) Bottom photo is a 3volt zener diode.(D119 or 120) Both of which are typically slathered with glue.

Top photo looks like someone tried to reflow solder on oxidized solder. Fresh solder doesn't mix well with oxidated solder.
 
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I see corrosive glue damage.Especially on the second photo. It starts on the topside and over time corrodes through the lead to the solder connection.When it gets that bad it usually damages the solder pad as well.
I see...thanks for explaining!
 
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