AM-1780A schematic needed or help with resistor R73

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patracy

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Trying to repair the AM-1780A I have. I've found resistor R73 is burnt. I've not found the schematics for the A model yet. Also googling the resistor numbers I can make out haven't found a value to replace it with. Does anyone have a TM for the AM-1780a with the schematic or could share what the resistor value is for this?
 

patracy

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I haven't found anything on public release for the "A" model. But I did see mention of:

TM 11-5820-898-20P. So maybe if there's the -10, 20, -34, exc. it would all share TM 11-5820-898 as the prefix I think.
 

patracy

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Well I pulled the resistor out, looks like it was a 10ohm resistor. Replaced the resistor and tried again. No love. There was one other resistor that looked like it got hot. But wasn't to the point this one was. I might try pulling that one out of the board and replace it. I did notice at least now when I key the intercom I see some current draw on my bench power supply. So some of it is working. But without a schematic, pretty much going to be a lost cause I think.

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SCSG-G4

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A long time ago, I had a stereo system that blew a resistor on one side, so I was able to look at the corresponding schematic for the other side and figure out what the value had been. When I replaced the resistor, I used four times the wattage, but the same Ohm value. Never had any more problems!
 

patracy

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There was one more discolored resistor in there. I'll pull it apart again and pull that one out to see if I have a suitable replacement. I think it was also a wirewound 2w resistor though. I also didn't think to patch audio into the input to see if it would do anything. Guess I'll at least try that before I declare it a lost cause.
 
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