LG 42PC1D No Video

[mnow]

Re: LG 42PC1D No Video

How do you put the PSU in self test?

[Andrew F. Ali]

Re: LG 42PC1D No Video

Pictures of the connector that goes from the PSU to the Main Bd. clearly focused so that I can see the Pin Nos. and their labels.

[mnow]

Re: LG 42PC1D No Video

This the one you want?

[Andrew F. Ali]

Re: LG 42PC1D No Video

To self-test your PSU you would need to build a test-lamp wit two (2) 120Vac household bulbs connected in series.
1. Disconnect all connectors from the PSU
2. Identify the connector with AC DET as pin1 and 3.3V-ON as pin13 (I can't see the connector No.)
3. Take a 100ohm resistor and solder it across pin 2 (RL-ON) and pin 3 (STB-5V)
4. Take a second 100ohm resistor and solder it across pin 3 (STB-5V) and pin 5 (VS-ON)
5. Take a third 100ohm resistor and solder it across pin 7 (M5V-ON) and pin 8 (STB-5V)
6. Take forth 100ohm resistor and solder it across pin 8 (STB-5V) and pin 13 (3.3V-ON)
7. Recheck that the soldering is clean and firm and there are no shorts to other pins
8. Connect the Test-bulb across VS and GND on the connector that would have gone to the Y-SUS Bd
9. Apply the ac
10 Observe: a. The Test-bulb should come on and light bright remaining on
b. The VA should come up and remain steady
c. 6V, 12V and all other voltages on the other connectors should come up and remain steady
(This will prove your PSU is OK)
Disconnect/remove the ac, wait for 10mins for the main caps, etc to drain and disconnect the Test-lamp.
Reconnect all connectors and inter-connectors except the one with the resistor connections going to the Main Bd.
Disconnect the Main Bd from the Control Bd.
Make the AUTO-GEN connection
Plug in the ac.
You should see the test patterns appear on the screen

[mnow]

Re: LG 42PC1D No Video

Got the test pattern finally and does not look good!
Rather blotchy picture.

[Andrew F. Ali]

Re: LG 42PC1D No Video

That looks like a faulty Z-SUS Bd. to me.

[Andrew F. Ali]

Re: LG 42PC1D No Video

BTY did you do the procedure outlined in post #24 to derive the test pattern?

[mnow]

Re: LG 42PC1D No Video

Just the last part of the procedure as I knew the PSU was good.
Thanks for that tip.
Did check the Z board and all voltages are good there.

[Andrew F. Ali]

Re: LG 42PC1D No Video

A faulty Panel can give that kind of picture also. Does this set have a separate Z-buffer Bd.?

[mnow]

Re: LG 42PC1D No Video

Set has seperate X, Y and Z boards.
Beginning to look like a defective panel to me!

[Andrew F. Ali]

Re: LG 42PC1D No Video

Could be a bad Z-buffer or Panel

[mnow]

Re: LG 42PC1D No Video

Checked all the voltages and bias on both Y and Z boards and all were normal.
PSU also OK.
What about the X board?
Have not seen any spec for that!
Would the X board cause this issue?
Also noticed when the test pattern changes, there is some lag when going from dark
to bright image (the dark pattern seems to take a bit to lighten up).
Really do miss good old CRT's and analog video!!!