Voltages 1/2 [resolved]
- Thread starter hbonilla
- Start date
Measure the voltage at pin 8 on the 9 pin socket of the offending side, then swap tubes and remeasure.
-PB
-PB
Do you get that voltage with both 12AT7's on the offending side?
Measure the resistance of pin 8 on the offending 9 pin socket.
12V over 366 Ohms is 32mA, which is way off target.
Can you carefully check the DC voltage on pin 7 of the offending socket?
Can you carefully check the DC voltage on pin 7 of the offending socket?
The red wire in that photo that you posted is not connected to the correct terminals.
Hi Paul,
I am back from a ver long trip and ready to tackle this. You say the red wire is not in the correct terminal, can you tell me which of the two red wires ypu are talking about? A or B? Again thanks for all your help.
I checked A and as per page 48 should be connected to 7L and B6, which is as it is.
I also checked B and as per page 41 shpuld be attached to "lug closest to the chassis plate in the center of the volume potentiometer" and the other side to 10L, which is where they are now.
Are you talking about a different red wire?
I am back from a ver long trip and ready to tackle this. You say the red wire is not in the correct terminal, can you tell me which of the two red wires ypu are talking about? A or B? Again thanks for all your help.
I checked A and as per page 48 should be connected to 7L and B6, which is as it is.
I also checked B and as per page 41 shpuld be attached to "lug closest to the chassis plate in the center of the volume potentiometer" and the other side to 10L, which is where they are now.
Are you talking about a different red wire?
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Sorry, it's been about a month since I posted that, and I don't see any errors. There is something pretty wonky going on here, you have 12V at the cathode of the offending side, the correct resistor in place, and 440V on the plate. This doesn't jive with the curves for a 12AT7.
This leaves us at flaky solder joints, which is very likely your issue. You can also swap the connections at OA and OB, and if the offending voltage stays put, then you know the C4S board is working.
-PB
This leaves us at flaky solder joints, which is very likely your issue. You can also swap the connections at OA and OB, and if the offending voltage stays put, then you know the C4S board is working.
-PB
We received this amplifier in today, and a solder joint on the center lug of one of the 9 pin sockets was not flowed all the way. Upon resoldering this connection, the amplifier works properly.
-PB
-PB
