M-80 refurb/repair

Thocom

AK Subscriber
Subscriber
Hi, first time posting in the Yamaha Forum. Have had Yamaha gear for the last 20 years and have never had an issue with any of it. I have one of the first digital Receivers out, the 1092 still in use as my home theater, and a new Adventage A1000 in my Basement HT as the pre/processor.

Anyway, I picked up an M-80 last weekend and haven't plugged it in yet. Looking it over, I found a 10A 250V ceramic fuse is blown. I have read the issues with the adhesive they used on the caps, and fear this may be an issue with this one..
See picture. I will dig into it and am willing to spend the time removing it. Any pointers? Should I replace every component that has come into contact with it?
Does this look like just the glue, or leaking capacitor?

Thanks,
Tom
 
Should I replace every component that has come into contact with it?
I would. Theres a jumper wire between the copper buss rails that usually is severely damaged by corrosion.
 
Power it up after cleaning and parts replace with a DBT.
You do not want that thing going Chernobyl (they will)

Look it over very closely for burnt resistors and exploded transistots.
 
Yup, they are zener.
So, I got all the glue clean up. The 1000uF caps seem to be in pretty good shape.
I'm having some issues with the parts list. It seems to be missing a boat load of parts that are listed on the drawing. Namely: R232, R230, R124, R 231, R229, R123.
Their parts list is horrible.
I was going to order the 1000uF 100V Nichicon Muse cap but these caps have three legs? Mouser carries the Muse cap in that value, but 2 legs. What's the deal? Is it just for securing the part, another - ?
I will bring them to work and test on our cap checker in the lab, but what's the third leg?

Thanks,
Tom
 

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I think that third leg is just a stabilizer.

Check to see if its pad is connected to any other components. Also check the case of the cap for markings indicating what it is. It should say something about it if it is important.
 
I think that third leg is just a stabilizer.

Check to see if its pad is connected to any other components. Also check the case of the cap for markings indicating what it is. It should say something about it if it is important.

Third leg is not used and not connected to anything but a solder pad.
 
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Yup, they are zener.
So, I got all the glue clean up. The 1000uF caps seem to be in pretty good shape.
I'm having some issues with the parts list. It seems to be missing a boat load of parts that are listed on the drawing. Namely: R232, R230, R124, R 231, R229, R123.
Their parts list is horrible.
I was going to order the 1000uF 100V Nichicon Muse cap but these caps have three legs? Mouser carries the Muse cap in that value, but 2 legs. What's the deal? Is it just for securing the part, another - ?
I will bring them to work and test on our cap checker in the lab, but what's the third leg?

Thanks,
Tom

Check my DSBG thread (in my sig) for a few of those. They may be listed.
 
All six are 330KΩ 5% 1/4 watt carbon film orange/orange/yellow/gold

You have to look at the schematic for those buggers. Get a little glue on them ? Corroded(green )leads?

Look at the disclaimer at the top of page 10 in the service manual. Second bullet statement.

Replacements can be either CF or MF.
I use these.
http://www.mouser.com/ProductDetail...GAEpiMZZMu61qfTUdNhG0IXHLFuiNndi2BdN7%2b2ESA=

Corroded? Haha, that's an understatement! Two of them are so far gone they have one side broken away from the board. Lol

Thanks guys,

Tom
 
The 1000 uF are not too far out of spec. One is 941uF and the other is around 993uF. I expected worse with this environmental nightmare of a glue that they used.lol

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SUCCESS!!!!

Sounds pretty good on a pair of Dynamo A25's driven with an iPad. Going to put on some good source and better speaks and give it a shot.

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