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M-80 issues again

Ftlbs

Ftlbs

Active Member
It looks like my post on my other M-80 project thread disappeared for some reason. To recap, Bright DBT. Disconnected #3 and got dim bulb and panel lights but TR111 gets very hot and starts cooking. Replaced D119&120, all caps on left channel for now, mica cap C159 by TR113 and R123,229, 231. I've tested every diode and transistor except TR101and haven't found anything wrong. Gotta be missing something someplace. Help?
 
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Replace D113 & 117 -- 7.5v zener diode.. Have another look at TR121.. in the ZDR circuit.
 
Make sure C125 is still serviceable. If it is still a Blackgate .. Get rid of it.
 
125 is a brand new Nichicon. I'll replace D113&117 tomorrow. TR111 in pic
 

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TR121 ok. C125 not shorted. Replaced D113 and 117. Now I'm getting a bright bulb, no panel lights, but no smoke either. Requested resistors in photo. WTH?
 

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Ftlbs said:
TR121 ok. C125 not shorted. Replaced D113 and 117. Now I'm getting a bright bulb, no panel lights, but no smoke either. Requested resistors in photo. WTH?
Click to expand...
One of the requested resistors is underneath one of those 3 watt resistors.. ( R187 ) If either 103 or 187 appear to be overheated the 2SK389 (TR101 ) is toast..
 
Ftlbs said:
TR121 ok. C125 not shorted. Replaced D113 and 117. Now I'm getting a bright bulb, no panel lights, but no smoke either. Requested resistors in photo. WTH?
Click to expand...
Is #3 still disconnected ? What happens when it is connected ? #3 is the +LB rail.
 
I also tested the new diodes prior to installation and also the two I removed and all tested good. Makes no sense to me
 
Unplugged #2 and got dim bulb and TR 111 started cooking again. Plugged in #3 with with #2 unplugged and R125 went up in smoke
 
I'm going to have to park this thing for a bit. The heart procedure ended up not working and it's on to the next option. Hopefully they get it figured out. I just have no energy at present and shortness of breath keeps me pretty well parked on my butt. Concentrating on anything is difficult at best. It quite frankly sucks, especially for someone who is very active. Definitely was not my retirement plan. Thanks for the assistance so far and I'll post when I can get back to it.
 
I hope cat hair isn't conductive. It's all over the boards. Top cover is a nice warm place for a kitty to hang out. Pussnobyl'd amp. Hope kitty didn't wiz in it.
After pulling the top cover off, I place every piece I work on outside on a cardboard slab transformer side down & blast out the whole chassis with low pressure air via my air compressor. Air tool held 1 or 2 feet away in the 40-60 psi range. There's too much crap for canned air to clean out, and pricey.

It's worked well so far for this redneck.

P.S. Apricot seeds are good for the heart, but they taste like ****. Best wishes champ.
 
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This isn't a medical forum so I'll keep it short, but I gotta expound a little regarding apricot seeds. It will keep the fellas servicing the M-80's and such around longer. It's natures miracle and I'm not shilling for any companies. Apricot seeds wreck cancer as well. Big pharma doesn't want anyone to know about it. Apricot seeds. Eat em up & stick around cuz I've only been doing bench work 4 years and need your help going forward. :beerchug:
 
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