Magnavox 25TR12 C102 Chassis 25P606-00AA wont power off
 

I am working on a Magnavox 25TR12 C102 (Chassis 25P606-00AA). Originally had
a problem where the set wont power on, had low standby voltage. Replaced
C432 (known problem) and fixed cold solder on 2 res next to the cap. Now,
the set automatically powers on when plugged in. It didnt do it right after
the replacement, so they may not be related. Nevertheless, I cant get it to
power off. Tried checked low voltage points but seems to be fine when its
on, guess the voltage must be backfeeding. Anyone have this issue before?
Thanks in advance.

Tim

Check the relay ...!!!!

kip

"GoodFeeling" wrote in message
m...
I am working on a Magnavox 25TR12 C102 (Chassis 25P606-00AA). Originally
had a problem where the set wont power on, had low standby voltage.
Replaced C432 (known problem) and fixed cold solder on 2 res next to the
cap. Now, the set automatically powers on when plugged in. It didnt do it
right after the replacement, so they may not be related. Nevertheless, I
cant get it to power off. Tried checked low voltage points but seems to be
fine when its on, guess the voltage must be backfeeding. Anyone have this
issue before? Thanks in advance.

Tim

Relay? How do I get there?

"kip" wrote in message
.. .
Check the relay ...!!!!

kip

"GoodFeeling" wrote in message
m...
I am working on a Magnavox 25TR12 C102 (Chassis 25P606-00AA). Originally
had a problem where the set wont power on, had low standby voltage.
Replaced C432 (known problem) and fixed cold solder on 2 res next to the
cap. Now, the set automatically powers on when plugged in. It didnt do it
right after the replacement, so they may not be related. Nevertheless, I
cant get it to power off. Tried checked low voltage points but seems to be
fine when its on, guess the voltage must be backfeeding. Anyone have this
issue before? Thanks in advance.

Tim

Ok Take it to a repair shop..
kip
"GoodFeeling" wrote in message
m...
Relay? How do I get there?

"kip" wrote in message
.. .
Check the relay ...!!!!

kip

"GoodFeeling" wrote in message
m...
I am working on a Magnavox 25TR12 C102 (Chassis 25P606-00AA). Originally
had a problem where the set wont power on, had low standby voltage.
Replaced C432 (known problem) and fixed cold solder on 2 res next to the
cap. Now, the set automatically powers on when plugged in. It didnt do it
right after the replacement, so they may not be related. Nevertheless, I
cant get it to power off. Tried checked low voltage points but seems to
be fine when its on, guess the voltage must be backfeeding. Anyone have
this issue before? Thanks in advance.

Tim

I thought you were referring to the news relay, not the electronic
component. I didnt imagine someone actually recommending such a fix. As far
as the problem, the relay is working fine, I have had a low voltage problem
and would like to know if there is a way to force the TV off so I can check
my voltage points.

"kip" wrote in message
.. .
Ok Take it to a repair shop..
kip
"GoodFeeling" wrote in message
m...
Relay? How do I get there?

"kip" wrote in message
.. .
Check the relay ...!!!!

kip

"GoodFeeling" wrote in message
m...
I am working on a Magnavox 25TR12 C102 (Chassis 25P606-00AA). Originally
had a problem where the set wont power on, had low standby voltage.
Replaced C432 (known problem) and fixed cold solder on 2 res next to the
cap. Now, the set automatically powers on when plugged in. It didnt do
it right after the replacement, so they may not be related.
Nevertheless, I cant get it to power off. Tried checked low voltage
points but seems to be fine when its on, guess the voltage must be
backfeeding. Anyone have this issue before? Thanks in advance.

Tim

GoodFeeling:
AGAIN..... check the relay (electronic component in television).
Make certain that it is de-energizing and that the contacts actually open
up.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


"GoodFeeling" wrote in message
m...
I thought you were referring to the news relay, not the electronic
component. I didnt imagine someone actually recommending such a fix. As
far
as the problem, the relay is working fine, I have had a low voltage
problem
and would like to know if there is a way to force the TV off so I can
check
my voltage points.

"kip" wrote in message
.. .
Ok Take it to a repair shop..
kip
"GoodFeeling" wrote in message
m...
Relay? How do I get there?

"kip" wrote in message
.. .
Check the relay ...!!!!

kip

"GoodFeeling" wrote in message
m...
I am working on a Magnavox 25TR12 C102 (Chassis 25P606-00AA).
Originally
had a problem where the set wont power on, had low standby voltage.
Replaced C432 (known problem) and fixed cold solder on 2 res next to
the
cap. Now, the set automatically powers on when plugged in. It didnt do
it right after the replacement, so they may not be related.
Nevertheless, I cant get it to power off. Tried checked low voltage
points but seems to be fine when its on, guess the voltage must be
backfeeding. Anyone have this issue before? Thanks in advance.

Tim

Well, if the set uses the 100uf 200v cap for C432, it doesn't use a
relay. The STR30130 regulator IC is switched on/off electrically. You
should always have about 150vdc on pin 3 and the output on pin 4 sits
about 15vdc when set is off and 130vdc when on. It's possible this IC
is bad, and also possible if C432 was open to have burnt resistors near
the IC.

Well for your info Relays do stay stuck on..Very common.
Next time let us know what you have done in the way of diagnosing
so we wont reply with a stupid suggestion.

kip
"GoodFeeling" wrote in message
m...
I thought you were referring to the news relay, not the electronic
component. I didnt imagine someone actually recommending such a fix. As far
as the problem, the relay is working fine, I have had a low voltage problem
and would like to know if there is a way to force the TV off so I can check
my voltage points.

"kip" wrote in message
.. .
Ok Take it to a repair shop..
kip
"GoodFeeling" wrote in message
m...
Relay? How do I get there?

"kip" wrote in message
.. .
Check the relay ...!!!!

kip

"GoodFeeling" wrote in message
m...
I am working on a Magnavox 25TR12 C102 (Chassis 25P606-00AA).
Originally had a problem where the set wont power on, had low standby
voltage. Replaced C432 (known problem) and fixed cold solder on 2 res
next to the cap. Now, the set automatically powers on when plugged in.
It didnt do it right after the replacement, so they may not be related.
Nevertheless, I cant get it to power off. Tried checked low voltage
points but seems to be fine when its on, guess the voltage must be
backfeeding. Anyone have this issue before? Thanks in advance.

Tim

On Thu, 26 May 2005 21:03:29 GMT, "GoodFeeling"
wrote:

I am working on a Magnavox 25TR12 C102 (Chassis 25P606-00AA). Originally had
a problem where the set wont power on, had low standby voltage. Replaced
C432 (known problem) and fixed cold solder on 2 res next to the cap. Now,
the set automatically powers on when plugged in. It didnt do it right after
the replacement, so they may not be related. Nevertheless, I cant get it to
power off. Tried checked low voltage points but seems to be fine when its
on, guess the voltage must be backfeeding. Anyone have this issue before?
Thanks in advance.

Tim

If this is the chassis that has Q410 next to the regulator ic, check
to see if it is shorted. Chuck

RonKZ650,

Thanks for the response, here is what I have come up with. I checked the
voltage at the regulator IC, and on pin 4, I have a little over 130vdc, when
the set is off (the set doesnt turn off, the display just goes a little dark
and the sound goes off), then the voltage turns down to around 120vdc on
pin 4. Does this sound like a bad reg IC or could it be another component
around it. I really need to understand what is actuallly dropping the
voltage, is it the Reg IC or should the input drop? Thanks for your help.


"RonKZ650" wrote in message
oups.com...
Well, if the set uses the 100uf 200v cap for C432, it doesn't use a
relay. The STR30130 regulator IC is switched on/off electrically. You
should always have about 150vdc on pin 3 and the output on pin 4 sits
about 15vdc when set is off and 130vdc when on. It's possible this IC
is bad, and also possible if C432 was open to have burnt resistors near
the IC.

Chuck,

There is a Q410, but not right next to the reg IC, I will check if it is
shorted though, thanks!


"Chuck" wrote in message
...
On Thu, 26 May 2005 21:03:29 GMT, "GoodFeeling"
wrote:

I am working on a Magnavox 25TR12 C102 (Chassis 25P606-00AA). Originally
had
a problem where the set wont power on, had low standby voltage. Replaced
C432 (known problem) and fixed cold solder on 2 res next to the cap. Now,
the set automatically powers on when plugged in. It didnt do it right
after
the replacement, so they may not be related. Nevertheless, I cant get it
to
power off. Tried checked low voltage points but seems to be fine when its
on, guess the voltage must be backfeeding. Anyone have this issue before?
Thanks in advance.

Tim

If this is the chassis that has Q410 next to the regulator ic, check
to see if it is shorted. Chuck

Checked Q410, it tests fine.

"GoodFeeling" wrote in message
...
Chuck,

There is a Q410, but not right next to the reg IC, I will check if it is
shorted though, thanks!


"Chuck" wrote in message
...
On Thu, 26 May 2005 21:03:29 GMT, "GoodFeeling"
wrote:

I am working on a Magnavox 25TR12 C102 (Chassis 25P606-00AA). Originally
had
a problem where the set wont power on, had low standby voltage. Replaced
C432 (known problem) and fixed cold solder on 2 res next to the cap. Now,
the set automatically powers on when plugged in. It didnt do it right
after
the replacement, so they may not be related. Nevertheless, I cant get it
to
power off. Tried checked low voltage points but seems to be fine when its
on, guess the voltage must be backfeeding. Anyone have this issue before?
Thanks in advance.

Tim

If this is the chassis that has Q410 next to the regulator ic, check
to see if it is shorted. Chuck

Update: Found that R432, a 1000 ohm resistor was open, so I replaced it.
Turn on the set and it smoked almost instantly. This res goes right to pin 2
of the IC. Does I am guessing that means the IC is bad. Does that sound
correct?


"GoodFeeling" wrote in message
...
RonKZ650,

Thanks for the response, here is what I have come up with. I checked the
voltage at the regulator IC, and on pin 4, I have a little over 130vdc,
when the set is off (the set doesnt turn off, the display just goes a
little dark and the sound goes off), then the voltage turns down to
around 120vdc on pin 4. Does this sound like a bad reg IC or could it be
another component around it. I really need to understand what is actuallly
dropping the voltage, is it the Reg IC or should the input drop? Thanks
for your help.


"RonKZ650" wrote in message
oups.com...
Well, if the set uses the 100uf 200v cap for C432, it doesn't use a
relay. The STR30130 regulator IC is switched on/off electrically. You
should always have about 150vdc on pin 3 and the output on pin 4 sits
about 15vdc when set is off and 130vdc when on. It's possible this IC
is bad, and also possible if C432 was open to have burnt resistors near
the IC.

I agree, the contacts could be stuck closed (welded, open coil, etc.)

Q400 is the one that sits right next to the IC, make sure it's not bad,
which is possible. If it's good then I think your regulator STR30130 is
bad. A burnt 1k resistor to pin 2 should turn off the IC, so if it's
still putting voltage out on pin 4 it's bad it looks like from my
perspective. The way it works is the input voltage (pin 3) stays a
constant aprox 150-160vdc regardless of whether the set is on or off.
Pin 2 is your on/off control, it sits around 15v when set is off along
with the output on pin 4. When pin 2 is turned high when the set is
turned on, pin 4 follows and outputs your 130v supply.

Check turn-off circuit. Usually just burns up R432 1K 1/2W,
but occasionally propagates further into D421, Z405, Q402.

In article ,
says...
I am working on a Magnavox 25TR12 C102 (Chassis 25P606-00AA). Originally had
a problem where the set wont power on, had low standby voltage. Replaced
C432 (known problem) and fixed cold solder on 2 res next to the cap. Now,
the set automatically powers on when plugged in. It didnt do it right after
the replacement, so they may not be related. Nevertheless, I cant get it to
power off. Tried checked low voltage points but seems to be fine when its
on, guess the voltage must be backfeeding. Anyone have this issue before?
Thanks in advance.

Hi Bill,

In the schematic, it says I should have 134vdc on the base of Q420, I have
160vdc. Is that to much? or is that normal? Thanks.


"Bill S" wrote in message
...
Check turn-off circuit. Usually just burns up R432 1K 1/2W,
but occasionally propagates further into D421, Z405, Q402.

In article ,
says...
I am working on a Magnavox 25TR12 C102 (Chassis 25P606-00AA). Originally
had
a problem where the set wont power on, had low standby voltage. Replaced
C432 (known problem) and fixed cold solder on 2 res next to the cap. Now,
the set automatically powers on when plugged in. It didnt do it right
after
the replacement, so they may not be related. Nevertheless, I cant get it
to
power off. Tried checked low voltage points but seems to be fine when its
on, guess the voltage must be backfeeding. Anyone have this issue before?
Thanks in advance.

Replaced STR30130, still toasts R431...

"RonKZ650" wrote in message
ups.com...
Q400 is the one that sits right next to the IC, make sure it's not bad,
which is possible. If it's good then I think your regulator STR30130 is
bad. A burnt 1k resistor to pin 2 should turn off the IC, so if it's
still putting voltage out on pin 4 it's bad it looks like from my
perspective. The way it works is the input voltage (pin 3) stays a
constant aprox 150-160vdc regardless of whether the set is on or off.
Pin 2 is your on/off control, it sits around 15v when set is off along
with the output on pin 4. When pin 2 is turned high when the set is
turned on, pin 4 follows and outputs your 130v supply.

New information: If I replace R432 and turn on the TV, it wont smoke... as
soon as I try to turn it off, the screen dims and R432 starts to get hot and
will smoke.

"GoodFeeling" wrote in message
...
Replaced STR30130, still toasts R431...

"RonKZ650" wrote in message
ups.com...
Q400 is the one that sits right next to the IC, make sure it's not bad,
which is possible. If it's good then I think your regulator STR30130 is
bad. A burnt 1k resistor to pin 2 should turn off the IC, so if it's
still putting voltage out on pin 4 it's bad it looks like from my
perspective. The way it works is the input voltage (pin 3) stays a
constant aprox 150-160vdc regardless of whether the set is on or off.
Pin 2 is your on/off control, it sits around 15v when set is off along
with the output on pin 4. When pin 2 is turned high when the set is
turned on, pin 4 follows and outputs your 130v supply.

Check/change the optocoupler ic346, check r432 may be open,c431,q400

In article ,
says...
In the schematic, it says I should have 134vdc on the base of Q420, I have
160vdc. Is that to much? or is that normal? Thanks.

Sounds like Q420 might be shorted. These are linear supplies,
so they don't mind being brought up slowly on a variac, if you
have one. B+ should follow the input up to about 14V and stop.
If it keeps rising, you can shut down before burning stuff up.

Also are you sure you replaced C432 with a good 100uf200v capacitor?
When this is bad, power supply runs high and sometimes causes this
resistor to burn.