Pye color TV, excessive screen voltage ?

A

Andre

Guest
Hi group
Found this antique TV - works for about two minutes then retrace lines
form and go away, eventually the whole screen goes white.

I've cleaned up around the multiplier and flyback, also focus pot - no
change.

TV is a Type 42K7228/15W

Any ideas ? I cannot find the screen pot anywhere (perhaps it has
none).

-A
 
Many years ago, I worked on some old Pye sets. This seems to be a symptom
of the HV module going bad.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Andre" <testing_h@yahoo.com> wrote in message
news:2c2cf14c.0310301622.3732ab39@posting.google.com...
Hi group
Found this antique TV - works for about two minutes then retrace lines
form and go away, eventually the whole screen goes white.

I've cleaned up around the multiplier and flyback, also focus pot - no
change.

TV is a Type 42K7228/15W

Any ideas ? I cannot find the screen pot anywhere (perhaps it has
none).

-A
 
"Jerry G." <jerryg50@hotmail.com> wrote in message news:<bnulu0$3o3$6@news.eusc.inter.net>...
Many years ago, I worked on some old Pye sets. This seems to be a symptom
of the HV module going bad.
Click to expand...
Thanks Jerry :)

Update :- resoldered about a dozen dry joints on mainboard and focus
pot, no change. I also cleaned focus pot and tube base thoroughly
which fixed the "flashing" problem but it still fades to white.

Any ideas where to get the HV module?

-A

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Andre" <testing_h@yahoo.com> wrote in message
news:2c2cf14c.0310301622.3732ab39@posting.google.com...
Hi group
Found this antique TV - works for about two minutes then retrace lines
form and go away, eventually the whole screen goes white.

I've cleaned up around the multiplier and flyback, also focus pot - no
change.

TV is a Type 42K7228/15W

Any ideas ? I cannot find the screen pot anywhere (perhaps it has
none).

-A
Click to expand...
 
"Andre" bravely wrote to "All" (02 Nov 03 04:21:05)
--- on the heady topic of "Re: Pye color TV, excessive screen voltage ?"

Recording the crt neck voltages before and after it fades to white might
be revealing. It seems like a crt biasing problem but it may be as
simple as an open video output plate resistor. Follow the video signal
chain to the crt. Beware of the high plate voltages in a tube tv set!


An> From: testing_h@yahoo.com (Andre)

An> "Jerry G." <jerryg50@hotmail.com> wrote in message
An> news:<bnulu0$3o3$6@news.eusc.inter.net>... > Many years ago, I worked
An> on some old Pye sets. This seems to be a symptom > of the HV module
An> going bad.
An> Thanks Jerry :)

An> Update :- resoldered about a dozen dry joints on mainboard and focus
An> pot, no change. I also cleaned focus pot and tube base thoroughly
An> which fixed the "flashing" problem but it still fades to white.

An> Any ideas where to get the HV module?


--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Andre" <testing_h@yahoo.com> wrote in message
news:2c2cf14c.0310301622.3732ab39@posting.google.com...
Hi group
Found this antique TV - works for about two minutes then retrace lines
form and go away, eventually the whole screen goes white.

I've cleaned up around the multiplier and flyback, also focus pot - no
change.

TV is a Type 42K7228/15W

Any ideas ? I cannot find the screen pot anywhere (perhaps it has
none).
Click to expand...
.... Well I defragged my TV and went all the way back to basic cable!
 
Check video output stage voltage, could be faulty filter cap.
 
peg@slingshot.co.nz (GPG) wrote in message news:<62069f15.0311030436.44a72564@posting.google.com>...
Check video output stage voltage, could be faulty filter cap.
Click to expand...
Hmm - thanks mate :) I will do this before I swap the expensive HV
block and focus pot.

Any ideas which filter cap it is or should I shotgun the lot :)

-A
 
On 4 Nov 2003 06:32:58 -0800, testing_h@yahoo.com (Andre) put finger
to keyboard and composed:

peg@slingshot.co.nz (GPG) wrote in message news:<62069f15.0311030436.44a72564@posting.google.com>...
Check video output stage voltage, could be faulty filter cap.

Hmm - thanks mate :) I will do this before I swap the expensive HV
block and focus pot.

Any ideas which filter cap it is or should I shotgun the lot :)
Click to expand...
IIRC, the older Pye, Philips, and Kriesler chassis used resistive
potential dividers in the focus and G2 areas. Check the 10Mohm (?)
focus and G2 resistors. Perhaps the bottom end of the divider is going
OC.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
 
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