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M-80 and it works! For now anyway

Ftlbs

Ftlbs

Active Member
I figured as long as I'm ordering parts for my other M-80 project I may as well peek at this one as well. It actually works perfectly but obviously needs some attention. It looks to me like it's an early model with no updates, SN:2861. Just curious on opinions. Address the obvious couple things that have some corrosion, or? Kinda hate to rip something apart that works but don't want another Chernobyl either. I'm hoping to get good at these since practically every broken 80/85 sold in the past couple years is probably in my garage. I was an aircraft missile systems/weapons tech in the Army and recently sold my auto restoration shop and retired so I have some knowledge and free time. Also, is this schematic an updated one? It has an orange path and orange notations on it. Thanks again!
 

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Ftlbs said:
I figured as long as I'm ordering parts for my other M-80 project I may as well peek at this one as well. It actually works perfectly but obviously needs some attention. It looks to me like it's an early model with no updates, SN:2861. Just curious on opinions. Address the obvious couple things that have some corrosion, or? Kinda hate to rip something apart that works but don't want another Chernobyl either. I'm hoping to get good at these since practically every broken 80/85 sold in the past couple years is probably in my garage. I was an aircraft missile systems/weapons tech in the Army and recently sold my auto restoration shop and retired so I have some knowledge and free time. Also, is this schematic an updated one? It has an orange path and orange notations on it. Thanks again!
Click to expand...
This one looks alot cleaner then the last one.
 
Sub SN 2401 models need TSB66H updates, but yours should have those.
There are some updates it looks like yours does not have. Not sure how important they are. From the pics it doesn't look like yours has Resistors R241-244 on the transistor legs?

I recommend a good digital service manual, like the one from analog alley. M-85 SM is best, as an M-85 is essentially an M-80 with all the updates.

Some tips if you are servicing a Yamaha M80-85 | Audiokarma Home Audio Stereo Discussion Forums

I have restored a SN 1836 unit and it took me a while to get all the updates and differences figured out.
M-80 Restore | Audiokarma Home Audio Stereo Discussion Forums
 
I was thinking it didn't have updates due to not having the resistors on the leg of those transistors. Any thoughts on the schematic? The orange made me think it's possibly an updated one?
 
Ftlbs said:
I was thinking it didn't have updates due to not having the resistors on the leg of those transistors. Any thoughts on the schematic? The orange made me think it's possibly an updated one?
Click to expand...
Use the M-85 schematic...For everything but the meter circuit board. The M-85 still has a few of the same mistakes and typo's that the M-80 schematic has.
 
Thanks. I just downloaded a nice legible copy from Norm. I wonder if the FedEx store would enlarge and laminate it. I really miss military manuals that had a lot more troubleshooting guidance.
 
Ftlbs said:
Thanks. I just downloaded a nice legible copy from Norm. I wonder if the FedEx store would enlarge and laminate it. I really miss military manuals that had a lot more troubleshooting guidance.
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When we had and Officemax. They would do 24" X 36" . Somebody sent me and M-80 schematic . Like Normans . Printed on Orajet Digital Printing Media , 26" X 36" Crystal clear reproduction and waterproof.
 
Ftlbs said:
I was thinking it didn't have updates due to not having the resistors on the leg of those transistors. Any thoughts on the schematic? The orange made me think it's possibly an updated one?
Click to expand...
The orange is the path that the audio signal travels, and voltage references. They only do one channel because the other is identical..
 
Office Depot can do what Dave said. I took an original B1 schematic to them and they enlarged it to 24x36 . The scanned copy looks great.


Athanasios
 
Thanks, I'll give them a try. The pdf I got from Norm at analog alley is very clean and legible. I'm sure it will be awesome printed in large format. It's so much better than the free download that you can't see anything on. Definitely a well spent $12.
 
I opened this one up so I could compare a working unit to the one in working on. I found this solder blob that's making a connection from the ground rail to a leg of resistor 101. It definitely shouldn't be there and I'm really curious how this thing is working like that
 

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Ftlbs said:
I opened this one up so I could compare a working unit to the one in working on. I found this solder blob that's making a connection from the ground rail to a leg of resistor 101. It definitely shouldn't be there and I'm really curious how this thing is working like that
Click to expand...
That is ugly, but those all connect to the same trace, so it doesn't matter. Perhaps a pad lifted on one of those and that is how a previous tech solved the issue.
 
Ftlbs said:
I opened this one up so I could compare a working unit to the one in working on. I found this solder blob that's making a connection from the ground rail to a leg of resistor 101. It definitely shouldn't be there and I'm really curious how this thing is working like that
Click to expand...
There was a buttload sonybond glue there; probably corroded the trace out. Ugly but it works.

So you're working on two M-80's huh? Cool. Maybe when they're all fixed you can bridge them & give the neighbors a soundgasm.
 
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I actually have an MX-1000, M-80, and 85 that work, two M-2's that I just finished that are working great and then the 80&85 that need help. I have two sets of Forte II's that I'm planning on pairing with the M-2's just for giggles. It's a sickness, it really is :)
 
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