Was recapping a Seeburg PA4-L6 when a pin broke off the 12BH7 socket. I am in the process of replacing the socket, however, the photos I took of the assembly before I started don't show where a couple of the capacitors connected to the socket, so I need to refer to the schematic.
It's a narrow, deep chassis with a lot of components crammed in there, and the stuff I needed to replace was in the bottom layer. I was struggling to disconnect a component from the socket when the pin broke. &^%$&^%$!
Just need the details of what hooks to the 12BH7 socket so I can put this back together.
It's a narrow, deep chassis with a lot of components crammed in there, and the stuff I needed to replace was in the bottom layer. I was struggling to disconnect a component from the socket when the pin broke. &^%$&^%$!
Just need the details of what hooks to the 12BH7 socket so I can put this back together.
Probably the capacitors connected to the plates, pins 1 and 6. Are they around 400V ratings, between 0.05uF to .5uF?
A resistor of around 30k to 50k should also connect to each of the plates.
A resistor of around 30k to 50k should also connect to each of the plates.
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The plate resistors were obvious, but there's some doubt about the three caps. I think I have it sorted though. One cap coming from the AGC switch probably goes to the grid pin 7. The other caps were a bit of a crap shoot, but slowly rewiring the new socket and by process of elimination, installing the obvious parts first and then narrowing down to the few mystery parts.
I'm testing it now, and the preamp is not passing much signal. Generator at the RCA jack (assuming that's the input) and the analyzer connected to the output terminals. I have to feed it 0dBm to see a minute output from the preamp.
The last time I recapped one of these, I remember getting a substantial signal output.
I'm not sure if I connected the caps to the wrong plates on the 12BH7. It was a coin toss as to which went where.
A schematic would clear up this mystery.
The last time I recapped one of these, I remember getting a substantial signal output.
I'm not sure if I connected the caps to the wrong plates on the 12BH7. It was a coin toss as to which went where.
A schematic would clear up this mystery.
I mentioned it to my customer and he provided it. I wish he'd provided it from the start! I did not know he had a diagram for this unit.
