04-09-2014, 06:33 PM
Okay!
Pulling Q404 and Q406 had no effect. I think I now know why, as we shall soon see.
Voltage measurements were revealing, as follows (all voltages referenced to chassis ground):
[Image: http://www.philcoradio.com/images/phorum...oltage.jpg]
No, the measured voltages at Q406 do not make sense - I'll have to remeasure that transistor to be sure.
But the lack of voltages at Q402 puzzled me.
I decided to look into things further. I found that PC401's terminals 2-3 (3.3K) and 3-4 (2.7K) were both open!
So PC401 is bad. With no voltage at Q402 as a result, I'm surprised any audio is getting through the board.
Now, here's the $64,000 question: Do I replicate PC401 with individual components, hoping the board has no other major issues, or do I hoist the white flag at this point and start gathering parts for that PLL MPX decoder?
Pulling Q404 and Q406 had no effect. I think I now know why, as we shall soon see.
Voltage measurements were revealing, as follows (all voltages referenced to chassis ground):
[Image: http://www.philcoradio.com/images/phorum...oltage.jpg]
No, the measured voltages at Q406 do not make sense - I'll have to remeasure that transistor to be sure.
But the lack of voltages at Q402 puzzled me.
I decided to look into things further. I found that PC401's terminals 2-3 (3.3K) and 3-4 (2.7K) were both open!
So PC401 is bad. With no voltage at Q402 as a result, I'm surprised any audio is getting through the board.
Now, here's the $64,000 question: Do I replicate PC401 with individual components, hoping the board has no other major issues, or do I hoist the white flag at this point and start gathering parts for that PLL MPX decoder?
--
Ron Ramirez
Ferdinand IN
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
