AM-1780A schematic needed or help with resistor R73

[patracy]

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?

 

[Guyfang]

Do you know the TM number? I know someone who has a bunch of TM's, but unless I give him a number, he wont even look.

 

[patracy]

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.

 

[SCSG-G4]

ARMY Property site says AM-1780 series for all the -898 TM's, but none are distribution "A".

 

[SCSG-G4]

Nothing of any use in the -890 series on the VIC-1.

 

[SCSG-G4]

I did find a PS Magazine warning about trying to use VIC-3 parts in a VIC-1 system - it kills the control box.

 

[papakb]

TM 11-5830-340-12 has some information about the VIC-1 in it but I don't see any reference to an R73.

 

[patracy]

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.

 

[Guyfang]

Sorry. No joy. But my buddy said maybe someone he knows, may have worked on them and would have an idea what could be the problem. He will ask.

 

[SCSG-G4]

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]

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.