Panasonic CT-32HX40B H.O.T. problem

[[email protected]]

I have a Panasonic CT-32HX40B HDTV. Some time ago, the flyback
transformer died, and I replaced it. Since then, there is no picture
when I turn the TV on. I know it's tuning the channels correctly
because I can hear the channel's audio through the speakers. I
thought to check the horizontal output transistor and found that the
base and emitter are both shorted to ground. Does anyone know what
could cause this, or what components to check? Any information would
be a great help.

Thanks,
Adam Dorsey
[email protected]

 

[Mark D. Zacharias]

I have a Panasonic CT-32HX40B HDTV. Some time ago, the flyback
transformer died, and I replaced it. Since then, there is no picture
when I turn the TV on. I know it's tuning the channels correctly
because I can hear the channel's audio through the speakers. I
thought to check the horizontal output transistor and found that the
base and emitter are both shorted to ground. Does anyone know what
could cause this, or what components to check? Any information would
be a great help.

Thanks,
Adam Dorsey
[email protected]

Base-emitter junction would normally read shorted because of the drive
transformer. Even out-of-circuit most HOT's have a 47 ohm resistor
internally across the E-B junction.

Your problem is elsewhere - maybe a 200 volt line down. You can check the
voltages at the driver transistors on the crt board.


Mark Z.

 

[[email protected]]

I have a Panasonic CT-32HX40B HDTV. Some time ago, the flyback
transformer died, and I replaced it. Since then, there is no picture
when I turn the TV on. I know it's tuning the channels correctly
because I can hear the channel's audio through the speakers. I
thought to check the horizontal output transistor and found that the
base and emitter are both shorted to ground. Does anyone know what
could cause this, or what components to check? Any information would
be a great help.

Thanks,
Adam Dorsey
[email protected]

Video and horiz blanking circuits

 

[[email protected]]

Base-emitter junction would normally read shorted because of the drive
transformer. Even out-of-circuit most HOT's have a 47 ohm resistor
internally across the E-B junction.

Your problem is elsewhere - maybe a 200 volt line down. You can check the
voltages at the driver transistors on the crt board.

Mark Z.

Thanks for the info.

I probably wasn't clear enough when I said this. The transistor is
fine; what's shorted is the base and emitter pads on the board
itself. It seemed weird that both pads were shorted to ground on the
board. The pads are laid out like this:

o C
B-o o-E

and B and E are both shorted to ground. Is this normal?

 

[AJ]

Reading across the windings of the h-drive transformer will give you a
moderately low resistance reading.

 

[[email protected]]

Thanks for all the help guys. I think I've found the problem and will
be doing more checking tomorrow (it's late).

Thanks again for all the info!