RCA projection TV Problem

[eganders]

My RCA rear projection TV has worked well after help from you TV
service people in January, 2005. It has
a chassis number of PTK195AC and is model P60812BL

At that time I found that the surface of the PC boards had some of the
coolent and other debris which I cleaned and that fixed the problem.

Coming home from vacation today, the main fuse from the AC input
failed. Upon replacing it, the convergence is all messed up. I went
into the service mode using the front panel as the service manual
describes, I can't seem to get the grid pattern that I got back in
2005. Can anyone tell me

1. What typically goes wrong when the main fuse blows and the picture
goes out of adjustment

2. How do you get into the built-in geometric alignment grid pattern?

I am into the service mode, but it does not seem to have any pattern
except the Pfor parameter) and V (for parameter value): on the
screen.

I would like to nurse this TV along for a while. It has given good
service and I have no reason to replace it other than the present
problem. I really don't want to get into it deeply. For example, I
would prefer NOT to get a chipper checker or have to hook an
oscilloscope to it.

sci.electronics.repair

 

[eganders]

My RCA rear projection TV has worked well after help from you TV
service people in January, 2005.  It has
a chassis number of PTK195AC and is model P60812BL

At that time I found that the surface of the PC boards had some of the
coolent and other debris which I cleaned and that fixed the problem.

Coming home from vacation today, the main fuse from the AC input
failed.  Upon replacing it, the convergence is all messed up.  I went
into the service mode using the front panel as the service manual
describes, I can't seem to get the grid pattern that I got back in
2005.  Can anyone tell me

1.  What typically goes wrong when the main fuse blows and the picture
goes out of adjustment

2.  How do you get into the built-in geometric alignment grid pattern?

I am into the service mode, but it does not seem to have any pattern
except the Pfor parameter) and V (for parameter value):  on the
screen.

I would like to nurse this TV along for a while.  It has given good
service and I have no reason to replace it other than the present
problem.  I really don't want to get into it deeply.  For example, I
would prefer NOT to get a chipper checker or have to hook an
oscilloscope to it.

sci.electronics.repair

Here is a photo of what the convergence problem looks like

http://img.photobucket.com/albums/v384/eganders/60inchConvergence100_1203.jpg

 

[eganders]

My RCA rear projection TV has worked well after help from you TV
service people in January, 2005.  It has
a chassis number of PTK195AC and is model P60812BL

At that time I found that the surface of the PC boards had some of the
coolent and other debris which I cleaned and that fixed the problem.

Coming home from vacation today, the main fuse from the AC input
failed.  Upon replacing it, the convergence is all messed up.  I went
into the service mode using the front panel as the service manual
describes, I can't seem to get the grid pattern that I got back in
2005.  Can anyone tell me

1.  What typically goes wrong when the main fuse blows and the picture
goes out of adjustment

2.  How do you get into the built-in geometric alignment grid pattern?

I am into the service mode, but it does not seem to have any pattern
except the Pfor parameter) and V (for parameter value):  on the
screen.

I would like to nurse this TV along for a while.  It has given good
service and I have no reason to replace it other than the present
problem.  I really don't want to get into it deeply.  For example, I
would prefer NOT to get a chipper checker or have to hook an
oscilloscope to it.

sci.electronics.repair

Here is a photo of the problem

http://img.photobucket.com/albums/v384/eganders/60inchConvergence100_1203.jpg

 

[eganders]

Time to actually get out the service manual and find out what particular
voltage to the convergence circuit you have lost, and what caused that
failure.

OK...

I checked the voltages out of J19701 connector from the power supply
to the convergence board. They are not to specification (at all).

pin 1 should be -45, is -1.8
pin 2 should be -15, is -1.9
pin 3 gnd
pin 4 should be +23, is +23.3
pin 5 should be +15, is 0
pin 6 should be -45, is 1.7

If the plug is pulled going to P19304, all the voltages go to 0 volts
at J19701 on the power supply board. The service manual says to
"disconnect power supply". I took that to mean pull J19701. I assume
that the power board is bad. My question is..
Was the board blown by the load of something wrong on the convergence
board, or just a bad component. I checked the input diode bridge and
it seems to be OK. I would guess I should replace the power supply
board. I wonder how much that is? I would hate to blow it after
changing it out. What are the chances of that?

 

[Mike S]

The last thing you should do is replace the power supply board. There's a
good chance something else in the TV may have caused a short or heavy load
on the power supply, and the new one would be blown.
Also it is very unlikely you could buy the board, or the price would be
outrageous. It is possible your convergence amp circuit has failed, this
should be tested/repaired first. Then the power supply should be
troubleshot and repaired.
Also, if you try to use adjustments in the service menu, or manual
adjustment of any kind to converge the image, your results are likely to be
very poor and unwatchable. Then when the TV is correctly repaired, it may
take HOURS longer to realign all the settings you have changed. Those
settings and/or adjustments are meant to fine-tune the picture when the
circuit is working correctly.