zenith model b835

6/13/2012 10:30:15 AMNick Magnano

First I want to say thank you Dennis and Paul for all of their help finding me the re-string diagram, it worked great.

My next dilemma is that the AM plays great but I can’t receive any FM channels, any thoughts on why? Anyone

6/13/2012 11:08:19 AMBill G.

Hi Nick,
I commonly restore Zenith H723, a little brother to yours. It is older and has no AFC.
This is a common problem. It usually is caused by silver mica disease in the discriminator IF.
This can be tested by reading the voltages on the 19T8 diodes, (pins 1, 2 and 3). If the discriminator is bad these voltages will be positive.

The problem is so common, I once replaced the discriminator without testing the voltages only to find the 19T8 was bad. I felt a little cheap. Be sure to test the tubes, 12AU6 and 19T8. They are rarely the cause, but it can happen.

Best Regards,

Bill Grimm

6/13/2012 4:41:12 PMNick

:Hi Nick,
: I commonly restore Zenith H723, a little brother to yours. It is older and has no AFC.
: This is a common problem. It usually is caused by silver mica disease in the discriminator IF.
: This can be tested by reading the voltages on the 19T8 diodes, (pins 1, 2 and 3). If the discriminator is bad these voltages will be positive.
:
: The problem is so common, I once replaced the discriminator without testing the voltages only to find the 19T8 was bad. I felt a little cheap. Be sure to test the tubes, 12AU6 and 19T8. They are rarely the cause, but it can happen.
:
:Best Regards,
:
:Bill Grimm
:

6/13/2012 4:42:05 PMNick

Thank you so much for the info I'll check those out

::Hi Nick,
:: I commonly restore Zenith H723, a little brother to yours. It is older and has no AFC.
:: This is a common problem. It usually is caused by silver mica disease in the discriminator IF.
:: This can be tested by reading the voltages on the 19T8 diodes, (pins 1, 2 and 3). If the discriminator is bad these voltages will be positive.
::
:: The problem is so common, I once replaced the discriminator without testing the voltages only to find the 19T8 was bad. I felt a little cheap. Be sure to test the tubes, 12AU6 and 19T8. They are rarely the cause, but it can happen.
::
::Best Regards,
::
::Bill Grimm
::
:
: