White-Westinghouse TV H.V. Shutdown

C

Chris F.

Guest
Model WTV-61904, mfd. Dec. 1999. Comes on for a second or two and goes
into HV shutdown. Sometimes it powers and runs for several hours without any
problems. I tried replacing the STR regulator this made no difference.
Powering with a Variac at 100VAC eliminates any problems. What other causes
should I be looking for, or is there an easy way to simply bypass the HV
shutdown? The shutdown feature is part of the TA1268N video IC, but I need a
pinout to determine which pin to disconnect.
Also this set was used very heavily, about 20 hours a day since it was new
(or so the owner tells me). Probably worn out anyway.
Thanks for any advice.

--
*********
Reply to: zappyman@hotmail.com
*********
 
Chris F:
Even though you have replaced the STR regulator chip..... have you verified
that the B+ actually being regulated at the correct voltage.... and that it
holds regulation when you vary the input AC line voltage from about 105 to
120 Volts.
There is more to the B+ regulation circuit than just the chip that you
replaced...... resistors, semiconductors, caps, dry or cracked solder
connections, etc. Also look for faulty electrolytics near and around the
STR circuitry but also the flyback area as well.
NO.... ABSOLUTELY NOT.... you do not want to bypass the HV shutdown......
this is a VERY IMPORTANT safety item.... this is NOT an option for a PROPER
and SAFE repair. This would be like trying to fix the brakes on your car
because the rear brakes are always hanging up.... so you disconnect and plug
off the brake lines going to the rear brakes...... not a very good idea.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
------------------------------------


"Chris F." <zappyman@nospam.com> wrote in message
news:ccUPa.5874$jL2.584569@ursa-nb00s0.nbnet.nb.ca...
Model WTV-61904, mfd. Dec. 1999. Comes on for a second or two and goes
into HV shutdown. Sometimes it powers and runs for several hours without
any
problems. I tried replacing the STR regulator this made no difference.
Powering with a Variac at 100VAC eliminates any problems. What other
causes
should I be looking for, or is there an easy way to simply bypass the HV
shutdown? The shutdown feature is part of the TA1268N video IC, but I need
a
pinout to determine which pin to disconnect.
Also this set was used very heavily, about 20 hours a day since it was
new
(or so the owner tells me). Probably worn out anyway.
Thanks for any advice.

--
*********
Reply to: zappyman@hotmail.com
*********
Click to expand...
 
NO.... ABSOLUTELY NOT.... you do not want to bypass the HV shutdown......
this is a VERY IMPORTANT safety item.... this is NOT an option for a PROPER
and SAFE repair.
Click to expand...
I'm not a monitor repair expert, but isn't that an x-ray issue? Something you
definately would want to avoid.

Jim
 
yes.... an X-RAY issue is a SAFETY item.
-------------------------------------

"RedWing196" <redwing196@aol.com> wrote in message
news:20030713123108.26581.00000310@mb-m18.aol.com...
NO.... ABSOLUTELY NOT.... you do not want to bypass the HV shutdown......
this is a VERY IMPORTANT safety item.... this is NOT an option for a
PROPER
and SAFE repair.

I'm not a monitor repair expert, but isn't that an x-ray issue? Something
you
definately would want to avoid.

Jim
Click to expand...
 
There are some components in the scans, and or power supply circuits,
that have become thermo sensitve. This is very common, more so than
failed semiconductors. You can try to troubleshoot the set by
measuring the performance of each of the areas, and comparing to the
service diagrams. Or, you can get a few cans of a product called
Freeze Mist or the equivelent, and use it to spray suspect components
to cool them down.

The power switch for the set must be recycled to reset a shut down
each time it goes off. You can use a heat gun to accellerate the
heating up of cooled areas, if heating components is required to test.

Most of the time, it is the capacitors in the various areas in these
sets that cause these types of failures. Sometimes it can be the high
voltage multiplier, but this is sort of rare.

Heating and cooling them will assist to find the fault. The use of an
ESR meter is the best way to varify a defective cap. Since your fault
is when the set it hot, you can heat the suspected caps with the heat
gun and also varify their ESR rating with the ESR meter.

There are a number of ways to approach this. With the experience and
the proper knowledge, your set should not be too difficult to service.

You may also find that if you like the set, it may be worth the
investment to have your local TV service center service the set for
you. This way, you will have it safely serviced.

Jerry Greenberg

--


"Chris F." <zappyman@nospam.com> wrote in message news:<ccUPa.5874$jL2.584569@ursa-nb00s0.nbnet.nb.ca>...
Model WTV-61904, mfd. Dec. 1999. Comes on for a second or two and goes
into HV shutdown. Sometimes it powers and runs for several hours without any
problems. I tried replacing the STR regulator this made no difference.
Powering with a Variac at 100VAC eliminates any problems. What other causes
should I be looking for, or is there an easy way to simply bypass the HV
shutdown? The shutdown feature is part of the TA1268N video IC, but I need a
pinout to determine which pin to disconnect.
Also this set was used very heavily, about 20 hours a day since it was new
(or so the owner tells me). Probably worn out anyway.
Thanks for any advice.
Click to expand...
 
--
*********
Reply to: zappyman@hotmail.com
*********
"Jerry Greenberg" <jerryg50@hotmail.com> wrote in message
news:460a833b.0307131402.1496b4a5@posting.google.com...
There are some components in the scans, and or power supply circuits,
that have become thermo sensitve. This is very common, more so than
failed semiconductors. You can try to troubleshoot the set by
measuring the performance of each of the areas, and comparing to the
service diagrams. Or, you can get a few cans of a product called
Freeze Mist or the equivelent, and use it to spray suspect components
to cool them down.

The power switch for the set must be recycled to reset a shut down
each time it goes off. You can use a heat gun to accellerate the
heating up of cooled areas, if heating components is required to test.

Most of the time, it is the capacitors in the various areas in these
sets that cause these types of failures. Sometimes it can be the high
voltage multiplier, but this is sort of rare.

Heating and cooling them will assist to find the fault. The use of an
ESR meter is the best way to varify a defective cap. Since your fault
is when the set it hot, you can heat the suspected caps with the heat
gun and also varify their ESR rating with the ESR meter.

There are a number of ways to approach this. With the experience and
the proper knowledge, your set should not be too difficult to service.

You may also find that if you like the set, it may be worth the
investment to have your local TV service center service the set for
you. This way, you will have it safely serviced.
Click to expand...
Thanks for the advice, but I already have a small shop of my own.....


Jerry Greenberg

--


"Chris F." <zappyman@nospam.com> wrote in message
news:<ccUPa.5874$jL2.584569@ursa-nb00s0.nbnet.nb.ca>...
Model WTV-61904, mfd. Dec. 1999. Comes on for a second or two and goes
into HV shutdown. Sometimes it powers and runs for several hours without
any
problems. I tried replacing the STR regulator this made no difference.
Powering with a Variac at 100VAC eliminates any problems. What other
causes
should I be looking for, or is there an easy way to simply bypass the HV
shutdown? The shutdown feature is part of the TA1268N video IC, but I
need a
pinout to determine which pin to disconnect.
Also this set was used very heavily, about 20 hours a day since it was
new
(or so the owner tells me). Probably worn out anyway.
Thanks for any advice.
Click to expand...
 
Good call Syl, there were a couple of bad caps in the regulator circuit. I
guess I didn't think the caps would go on something this new, but I guess
this set was used quite heavily......
I had a Hitachi with a similar problem a few months ago, except it was
regulating perfectly but still shutting down intermittently. Someone on this
NG was familiar with the problem, and said it was a manufacture defect and
the only solution was bypassing the HV shutdown (which I did). It was either
that, or junk the set.
Also, given the vast number of harmful things people subject their bodies
to - cigarettes, alcohol, cholesterol, STD's, etc - I personally think TV
radiation is the least of their worries.
Thanks for the advice though!

--
*********
Reply to: zappyman@hotmail.com
*********
"Sofie" <sofie@olypen.com> wrote in message
news:vh2s6rr8vgun41@corp.supernews.com...
Chris F:
Even though you have replaced the STR regulator chip..... have you
verified
that the B+ actually being regulated at the correct voltage.... and that
it
holds regulation when you vary the input AC line voltage from about 105 to
120 Volts.
There is more to the B+ regulation circuit than just the chip that you
replaced...... resistors, semiconductors, caps, dry or cracked solder
connections, etc. Also look for faulty electrolytics near and around the
STR circuitry but also the flyback area as well.
NO.... ABSOLUTELY NOT.... you do not want to bypass the HV shutdown......
this is a VERY IMPORTANT safety item.... this is NOT an option for a
PROPER
and SAFE repair. This would be like trying to fix the brakes on your car
because the rear brakes are always hanging up.... so you disconnect and
plug
off the brake lines going to the rear brakes...... not a very good idea.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
------------------------------------


"Chris F." <zappyman@nospam.com> wrote in message
news:ccUPa.5874$jL2.584569@ursa-nb00s0.nbnet.nb.ca...
Model WTV-61904, mfd. Dec. 1999. Comes on for a second or two and goes
into HV shutdown. Sometimes it powers and runs for several hours without
any
problems. I tried replacing the STR regulator this made no difference.
Powering with a Variac at 100VAC eliminates any problems. What other
causes
should I be looking for, or is there an easy way to simply bypass the HV
shutdown? The shutdown feature is part of the TA1268N video IC, but I
need
a
pinout to determine which pin to disconnect.
Also this set was used very heavily, about 20 hours a day since it was
new
(or so the owner tells me). Probably worn out anyway.
Thanks for any advice.

--
*********
Reply to: zappyman@hotmail.com
*********
Click to expand...
 
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