Philips 32PT563S w/ Horizontal Short Issue

T

Tom Tom

Guest
I am looking for help to find short that develops in the horizontal section
of a Philips 32PT563S37G (Chassis L01.1UAC-7638).

When the TV was first going out, it would be difficult to turn on. It would
take several attempts at turning on to get it to stay on. It started with
the right side of the screen wavering along the edge and somewhat folding
over on itself. As the TV would be turned on repeatly it would eventually
settle down and stay on and be ok. Then finally one day the TV died and the
HOT (horiz output transistor) shorted out (zero ohms across all junctions).
This wavering on the edge of the screen only happens on the right, never on
the left.

I've replaced the HOT twice with a NTE2636 - can't locate a true replacement
for the BU4508DX - I can only get the BU4508AF which doesn't have the Re and
damper diode built-in. I have replaced every electrolytic capacitor in the
TV that's on the main board (not any on the SSB or CRT yoke board), along
with two PNP (BC32725 & C557B) & two NPN (BC33725 & C547B) transistors. The
electrolytics were all replaced with the same manufactuer - I got them all
from Mouser.com. And yes, I did replace the capacitor 2455 along with the
NPN/PNP transistors nearby.

While I had the HOT out of the TV I tried checking the flyback (part #
OV2076) windings with an ohm meter. I used a diagram for a HR8380 as a
reference. I was getting some low ohm readings on the primary and secondary
voltage output for video and other circuits - the readings were around 1 to
2 ohms. I tried checking the ohm reading on the HV output side and wasn't
getting any shorted out or low ohm reading - and I don't recall much of any
reading on higher ohm ranges.

The right side of the screen was developing a wave along it (not straight)
just before it died the last time. The TV only lasted for about 15-20 mins
before the HOT shorted out again. Now there is a high pitch ticking sound
from the TV when the power cord is plugged in.

I'm waiting for a Sams Photofacts to arrive for this - but could use any
help / advice about the right side horizontal issue.

Thanks,
Glenn
 
"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:0ff3b4p9jl4484dijhqir9h3a4ar22h4n4@4ax.com...
On Sun, 24 Aug 2008 15:58:27 GMT, "Tom Tom" <sometomtom@tomtom.com
put finger to keyboard and composed:

I am looking for help to find short that develops in the horizontal
section
of a Philips 32PT563S37G (Chassis L01.1UAC-7638).

When the TV was first going out, it would be difficult to turn on. It
would
take several attempts at turning on to get it to stay on. It started with
the right side of the screen wavering along the edge and somewhat folding
over on itself. As the TV would be turned on repeatly it would eventually
settle down and stay on and be ok. Then finally one day the TV died and
the
HOT (horiz output transistor) shorted out (zero ohms across all
junctions).
This wavering on the edge of the screen only happens on the right, never
on
the left.

I'm not familiar with that particular chassis, but have you checked
the tuning cap in the horizontal section? Is there a high voltage
(2kV) ceramic cap nearby?
Click to expand...
I don't recall seeing anything resembling a tuning capacitor. This chassis
seems to have minimal components to it. But I'll look at the schematic and
see if one is listed on it. I'm taking a step back right now while I do some
more research and thinking on this problem.

Glenn
 
"Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message
news:xQgsk.5721$Fr1.3774@newsfe03.iad...
Tom Tom wrote:
I am looking for help to find short that develops in the horizontal
section of a Philips 32PT563S37G (Chassis L01.1UAC-7638).

When the TV was first going out, it would be difficult to turn on. It
would take several attempts at turning on to get it to stay on. It
started with the right side of the screen wavering along the edge and
somewhat folding over on itself. As the TV would be turned on repeatly
it would eventually settle down and stay on and be ok. Then finally one
day the TV died and the HOT (horiz output transistor) shorted out (zero
ohms across all junctions). This wavering on the edge of the screen only
happens on the right, never on the left.

I've replaced the HOT twice with a NTE2636 - can't locate a true
replacement for the BU4508DX - I can only get the BU4508AF which doesn't
have the Re and damper diode built-in. I have replaced every
electrolytic capacitor in the TV that's on the main board (not any on the
SSB or CRT yoke board), along with two PNP (BC32725 & C557B) & two NPN
(BC33725 & C547B) transistors. The electrolytics were all replaced with
the same manufactuer - I got them all from Mouser.com. And yes, I did
replace the capacitor 2455 along with the NPN/PNP transistors nearby.

While I had the HOT out of the TV I tried checking the flyback (part #
OV2076) windings with an ohm meter. I used a diagram for a HR8380 as a
reference. I was getting some low ohm readings on the primary and
secondary voltage output for video and other circuits - the readings were
around 1 to 2 ohms. I tried checking the ohm reading on the HV output
side and wasn't getting any shorted out or low ohm reading - and I don't
recall much of any reading on higher ohm ranges.

The right side of the screen was developing a wave along it (not
straight) just before it died the last time. The TV only lasted for
about 15-20 mins before the HOT shorted out again. Now there is a high
pitch ticking sound from the TV when the power cord is plugged in.

I'm waiting for a Sams Photofacts to arrive for this - but could use any
help / advice about the right side horizontal issue.

Thanks,
Glenn



Replace the Flyback and of course the HOT again !

Sorry, but when a HOT is taken out in that fashion, the flyback is
almost all the time the cause along with the low voltage supply
sections some circuits use from the flyback.


http://webpages.charter.net/jamie_5"
Click to expand...
Thanks for the help. I've been thinking that was going to be my next step.
I don't see any markings inside the TV to indicate what the CRT voltage
should be set to - I think I saw something in another posting with the same
chassis (a 27" TV) that said 27KV. I also need to source a HV probe.

Any suggestions for a good source online for flyback transformers? When I
researched I found one priced at $17.95 and another at $39.99. Just not too
sure of the quality I would be getting.

Glenn
 
Tom Tom wrote:
I am looking for help to find short that develops in the horizontal section
of a Philips 32PT563S37G (Chassis L01.1UAC-7638).

When the TV was first going out, it would be difficult to turn on. It would
take several attempts at turning on to get it to stay on. It started with
the right side of the screen wavering along the edge and somewhat folding
over on itself. As the TV would be turned on repeatly it would eventually
settle down and stay on and be ok. Then finally one day the TV died and the
HOT (horiz output transistor) shorted out (zero ohms across all junctions).
This wavering on the edge of the screen only happens on the right, never on
the left.

I've replaced the HOT twice with a NTE2636 - can't locate a true replacement
for the BU4508DX - I can only get the BU4508AF which doesn't have the Re and
damper diode built-in. I have replaced every electrolytic capacitor in the
TV that's on the main board (not any on the SSB or CRT yoke board), along
with two PNP (BC32725 & C557B) & two NPN (BC33725 & C547B) transistors. The
electrolytics were all replaced with the same manufactuer - I got them all
from Mouser.com. And yes, I did replace the capacitor 2455 along with the
NPN/PNP transistors nearby.

While I had the HOT out of the TV I tried checking the flyback (part #
OV2076) windings with an ohm meter. I used a diagram for a HR8380 as a
reference. I was getting some low ohm readings on the primary and secondary
voltage output for video and other circuits - the readings were around 1 to
2 ohms. I tried checking the ohm reading on the HV output side and wasn't
getting any shorted out or low ohm reading - and I don't recall much of any
reading on higher ohm ranges.

The right side of the screen was developing a wave along it (not straight)
just before it died the last time. The TV only lasted for about 15-20 mins
before the HOT shorted out again. Now there is a high pitch ticking sound
from the TV when the power cord is plugged in.

I'm waiting for a Sams Photofacts to arrive for this - but could use any
help / advice about the right side horizontal issue.

Thanks,
Glenn



Replace the Flyback and of course the HOT again !
Click to expand...

Sorry, but when a HOT is taken out in that fashion, the flyback is
almost all the time the cause along with the low voltage supply
sections some circuits use from the flyback.


http://webpages.charter.net/jamie_5"
 
On Sun, 24 Aug 2008 15:58:27 GMT, "Tom Tom" <sometomtom@tomtom.com>
put finger to keyboard and composed:

I am looking for help to find short that develops in the horizontal section
of a Philips 32PT563S37G (Chassis L01.1UAC-7638).

When the TV was first going out, it would be difficult to turn on. It would
take several attempts at turning on to get it to stay on. It started with
the right side of the screen wavering along the edge and somewhat folding
over on itself. As the TV would be turned on repeatly it would eventually
settle down and stay on and be ok. Then finally one day the TV died and the
HOT (horiz output transistor) shorted out (zero ohms across all junctions).
This wavering on the edge of the screen only happens on the right, never on
the left.
Click to expand...
I'm not familiar with that particular chassis, but have you checked
the tuning cap in the horizontal section? Is there a high voltage
(2kV) ceramic cap nearby?

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
On Sun, 24 Aug 2008 21:06:16 GMT, "Tom Tom" <sometomtom@tomtom.com>
put finger to keyboard and composed:

"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:0ff3b4p9jl4484dijhqir9h3a4ar22h4n4@4ax.com...

I'm not familiar with that particular chassis, but have you checked
the tuning cap in the horizontal section? Is there a high voltage
(2kV) ceramic cap nearby?


I don't recall seeing anything resembling a tuning capacitor. This chassis
seems to have minimal components to it. But I'll look at the schematic and
see if one is listed on it. I'm taking a step back right now while I do some
more research and thinking on this problem.

Glenn
Click to expand...
A tuning cap is invariably connected across the C-E terminals of the
horizontal output transistor. It forms part of the horizontal resonant
circuit and has a typical value of the order of a few nanofarads.

This Philips set uses a different chassis, but see the section half
way down the page where the author discusses a failure in the tuning
cap:
http://www.siliconchip.com.au/cms/A_30297/article.html

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
On 24 ago, 08:58, "Tom Tom" <sometom...@tomtom.com> wrote:
I am looking for help to find short that develops in the horizontal section
of a Philips 32PT563S37G (Chassis L01.1UAC-7638).

When the TV was first going out, it would be difficult to turn on. It would
take several attempts at turning on to get it to stay on. It started with
the right side of the screen wavering along the edge and somewhat folding
over on itself. As the TV would be turned on repeatly it would eventually
settle down and stay on and be ok. Then finally one day the TV died and the
HOT (horiz output transistor) shorted out (zero ohms across all junctions).
This wavering on the edge of the screen only happens on the right, never on
the left.

I've replaced the HOT twice with a NTE2636 - can't locate a true replacement
for the BU4508DX - I can only get the BU4508AF which doesn't have the Re and
damper diode built-in. I have replaced every electrolytic capacitor in the
TV that's on the main board (not any on the SSB or CRT yoke board), along
with two PNP (BC32725 & C557B) & two NPN (BC33725 & C547B) transistors. The
electrolytics were all replaced with the same manufactuer - I got them all
from Mouser.com. And yes, I did replace the capacitor 2455 along with the
NPN/PNP transistors nearby.

While I had the HOT out of the TV I tried checking the flyback (part #
OV2076) windings with an ohm meter. I used a diagram for a HR8380 as a
reference. I was getting some low ohm readings on the primary and secondary
voltage output for video and other circuits - the readings were around 1 to
2 ohms. I tried checking the ohm reading on the HV output side and wasn't
getting any shorted out or low ohm reading - and I don't recall much of any
reading on higher ohm ranges.

The right side of the screen was developing a wave along it (not straight)
just before it died the last time. The TV only lasted for about 15-20 mins
before the HOT shorted out again. Now there is a high pitch ticking sound
from the TV when the power cord is plugged in.

I'm waiting for a Sams Photofacts to arrive for this - but could use any
help / advice about the right side horizontal issue.

Thanks,
Glenn
Click to expand...
the highland electrix site has a long list of common philips faults.
-B
 
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