hissing chopper

[BigTom]

Panasonic tc-63R50N color tv

HOT ok. 106v at Collector.
no HV
no heater.
sound ok.
can change channels + adjust volume.

this set has a separate p/s board using an STR51213.
tested resistance on this ic, no pins shorted.

the chopper is making a squealing noise while turned on.

done the usual, esr caps, checked all the big resistors, transistors.

what should i look at next?

 

[JURB6006]

The noisy chopper might be normal if there is no horizontal drive. It's
probably supposed to be locked to the line rate and there's nothing for it to
lock onto.

I'd look into why there is no drive.

JURB

 

[CJT]

Panasonic tc-63R50N color tv

HOT ok. 106v at Collector.
no HV
no heater.
sound ok.
can change channels + adjust volume.

this set has a separate p/s board using an STR51213.
tested resistance on this ic, no pins shorted.

the chopper is making a squealing noise while turned on.

done the usual, esr caps, checked all the big resistors, transistors.

what should i look at next?

You've got a TV with a chopper? I've never seen such a thing.

Maybe you mean something in the horizontal output section?

 

[JURB6006]

Maybe you mean something in the horizontal output section?

No, chopper is sorta slang for the output device in a switched mode power
supply, or the entire power supply itself.

(unless there are long forks sticking out of the front)

JURB

 

[CJT]

No, chopper is sorta slang for the output device in a switched mode power
supply, or the entire power supply itself.

(unless there are long forks sticking out of the front)

JURB

It seems odd (to me) to re-use a term that already applies to a
different electronic device.

 

[James Sweet]

It seems odd (to me) to re-use a term that already applies to a
different electronic device.

What device? The only electronics I've ever heard "chopper" apply to is the
switching transistor in a SMPS.

 

[CJT]

What device? The only electronics I've ever heard "chopper" apply to is the
switching transistor in a SMPS.

Youngster. <g>

This should yield plenty of examples:

http://www.google.com/search?as_q=c...s_occt=any&as_dt=i&as_sitesearch=&safe=images