01-15-2016, 09:23 AM
Hi,
I've been working on this Model 8A..was dead, now playing, however I have too much voltage on both sides of the circuit for example...checking plate voltage on the 6k7's, 6l7, 5y3, 6c5, spec is 240v. I'll have 245v for about 5min then it jumps to 345v. In turn the voltage at pin4 of the 6k7's and 6l7 should be 105v and I have 155v(exactly 1/2 of the excess plate voltage. Bias voltage reacts the same 50v more. All resistors & tubes check good but I'm replacing all resistors anyways. Have about 8 to go...The only oddity is no signal thru the antenna wire(if it's correct..wire goes to thru band selector switch to ground) and volume seems low until 50% after 70% it's a little distorted....If I hook an antenna lead up to the cap of the 6l7 or plate wire of the 6k7 reception is outstanding. Is there something obvious I am missing? Transformer is super cool, even after an hour. The only thing I have not checked is field coil resistance. Will do that tonight. All three bands are sensitive..can pick up more stations then my 38-116 hi fidelity.
Thanks in advance for any suggestions
Bob
I've been working on this Model 8A..was dead, now playing, however I have too much voltage on both sides of the circuit for example...checking plate voltage on the 6k7's, 6l7, 5y3, 6c5, spec is 240v. I'll have 245v for about 5min then it jumps to 345v. In turn the voltage at pin4 of the 6k7's and 6l7 should be 105v and I have 155v(exactly 1/2 of the excess plate voltage. Bias voltage reacts the same 50v more. All resistors & tubes check good but I'm replacing all resistors anyways. Have about 8 to go...The only oddity is no signal thru the antenna wire(if it's correct..wire goes to thru band selector switch to ground) and volume seems low until 50% after 70% it's a little distorted....If I hook an antenna lead up to the cap of the 6l7 or plate wire of the 6k7 reception is outstanding. Is there something obvious I am missing? Transformer is super cool, even after an hour. The only thing I have not checked is field coil resistance. Will do that tonight. All three bands are sensitive..can pick up more stations then my 38-116 hi fidelity.
Thanks in advance for any suggestions
Bob
