[Boatanchors] Questions on AN/GRR-5 Receiver

[WA5CAB at cs.com]

Dave,

You don't mention what supply voltage you are trying to operate the receiver 
from but as you mention a relay clunk, I assume 115 VAC.  E-101, the Input 
Vibrator, does not run when operating on 115 VAC.  E-102, the Filament Voltage 
Vibrator runs off of the same supply that operates the relay, but through an NO 
contact on the relay.  If K-101 pulls in, then CR-101 and C-101 must be 
working.  If E-102 doesn't start, then that leaves L-108 or contacts 20/21 on K-101. 
 Check for around 6 volts on pin 4 of E-102.  If present, E-102 is running or 
E-102 is bad.  If not present, check the other side of L-108.  If present, 
L-108 is open.  If not present, check contacts 20 and 21 on K-101.  If present 
on 21 and not on 20, the relay contacts are bad.  If present on 20, start over. 
 One of the previous steps was misdiagnosed.

However, the most common failures in the PP-308/URR are the vibrators (almost 
always fixable), the loudspeaker and the filament voltage rectifiers CR-102.  
The rectifiers are mounted in the rear of the cabinet and connected to the 
cabinet wiring harness.  Check their front to back ratio, bearing in mind that 
the anodes are grounded.  If they are bad, the recommended fix is to remove the 
leads from the two halves of the rectifier to pins 2 and 4 of P-101.  Mount a 
bridge rectifier block to the rear wall of the power supply.  Connect the AC 
input terminals of the bridge to pins 2 and 4 of J-101.  Ground the negative 
bridge terminal.  Leave the positive terminal unconnected.  A PP-308 so 
modified will still work in an unmodified cabinet unless CR-102 is shorted, which 
isn't usually the case.

In a message dated 8/25/2007 10:21:09 PM Central Daylight Time, n7rk at cox.net 
writes: 
> I have an AN/GRR-5 with a dead power supply. The relay clunks when 
> turned on but the vibrators are not coming on. I have tested both 
> vibrators and they are OK and all fuses are good.
> 
> Any suggestions before I start tearing into this? I do have the manual.
> 
> I seem to recall something like this with the AN/GRR-5 I had as a kid in 
> the sixties but it's too long ago to recall what it was and the fix.
> 

Robert Downs - Houston
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