04-28-2017, 10:06 AM
Replaced R306 with another 1k ohm reisistor but learned something new and a possible fault. ~tube socket carbon flash or carbon trace?
on my diagram, i disconnected the red wire from T4 2nd IF.
resistance from blue to red was correct.
resistance from red to chassis was 250kohms
resistance from blue to chassis was 250kohms
with the 7h7 V3 removed, the resistances stayed the same.
i moved over to T3 1st IF circuit since its smilar to compare.
i disconnected the red wire from T3 1st IF.
resistance from blue to red was correct.
resistance from red to chassis was in the 3 to 5 Meg ohms
resistance from blue to chassis was 3 to 5 meg ohms
with the 7h7 V2 removed, the resistances stayed high.
I re-terminated all my wires and added another R306 1kohm resistor
I reinstalled V2 7h7 tube
I kept V3 tube socket empty...
I had my volt meter red lead attached to v3 7h7 pin 2... volt meter set to AC volts.
I powered up and heard the audible crinkle of R306 beginning to pass too much current.
I also saw smoke coming out of v3 pin 2 coming out the bottom and out the top.
I had no voltage reading on my meter.
we have (terry and I ) that i have a bad tube socket. something called a Carbon trace or something like that.
Looking now for a replacement Loktal socket or the option of disecting this socket, cleaning it up and re-installing the old pin. dono really yet which way i will go.
on my diagram, i disconnected the red wire from T4 2nd IF.
resistance from blue to red was correct.
resistance from red to chassis was 250kohms
resistance from blue to chassis was 250kohms
with the 7h7 V3 removed, the resistances stayed the same.
i moved over to T3 1st IF circuit since its smilar to compare.
i disconnected the red wire from T3 1st IF.
resistance from blue to red was correct.
resistance from red to chassis was in the 3 to 5 Meg ohms
resistance from blue to chassis was 3 to 5 meg ohms
with the 7h7 V2 removed, the resistances stayed high.
I re-terminated all my wires and added another R306 1kohm resistor
I reinstalled V2 7h7 tube
I kept V3 tube socket empty...
I had my volt meter red lead attached to v3 7h7 pin 2... volt meter set to AC volts.
I powered up and heard the audible crinkle of R306 beginning to pass too much current.
I also saw smoke coming out of v3 pin 2 coming out the bottom and out the top.
I had no voltage reading on my meter.
we have (terry and I ) that i have a bad tube socket. something called a Carbon trace or something like that.
Looking now for a replacement Loktal socket or the option of disecting this socket, cleaning it up and re-installing the old pin. dono really yet which way i will go.