RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

[Michale32086]

I just got in a really nice (at least cosmetically) RCA 42PA30RQ Plasma TV...

Usually with Plasmas, if there is not something obvious (IE Blown Caps, Broken/Burnt PCB) wrong that would be an easy fix, I just scrap it for parts.

But this seems to be a different kind of Plasma..

For one thing, it doesn't weigh a ton and a half. I can easily (relatively speaking ) lift it by myself.. And it's in REALLY great cosmetic shape..

So, here is the symptoms...

Plugged in, push power button. Power Light goes from red to blue. No picture on the screen at all.. Not even a faint glow.. No light whatsoever.. Totally dead. I was told there is sound, but I can't confirm that....

My first thought. Inverter/Power PCB... Pull the cover off.. All boards are in great shape. No blown caps, no burn marks, no breaks, no nuttin'...

Given this picture:

http://sjfm.us/temp/42PA30RQ-1.jpg

..... which board is the likely culprit as in which one do I want to swap out first...

Thanx in advance for any assist...

[vinceroger69]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

have you looked at any of the threads here same set as yours same fault
https://www.badcaps.net/forum/search...archid=3746340

[Michale32086]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

ACK!!!!

I did a GOOGLE search, but not a BadCaps search..

Mea culpa....

I'll read thru them right now.. Thanx

[vinceroger69]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

im sure you will find some good info and what to test/change.

[Michale32086]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

Thanx for that link.. A LOT of good info...

I am going to try the X-Main first as that seems to be the culprit in the majority of those threads...

Thanx again...

[vinceroger69]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

im sure ive read you have to replace three boards at the same time? maybe one of the more experienced members will chime in.

[tom66]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

You can try checking for shorted transistors on the xmain.

[Michale32086]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

Visually, everything looks OK...

I don't really have the equipment (beyond a simple voltmeter) nor the expertise to troubleshoot actual boards, much to my chagrin...

My best diagnostic tool in my inventory are my eyes and even then, it's going downhill..

Thanx for the reply....

[vinceroger69]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

is your voltmeter a digital one?

[Michale32086]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

"He CAN be taught!!!"
-Genie, ALLADIN

http://www.wikihow.com/Test-a-Transistor

[Michale32086]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

is your voltmeter a digital one?

Yea...

[tom66]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

In this case it's more appropriate to test a MOSFET or IGBT, these devices are slightly different. (High power semiconductors.)

[Michale32086]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

More info... The LED on the TCON board blinks..

off for 2 seconds, on for 7 seconds, off for 2 seconds, on for 7 seconds...

According to Tom66 on one of those threads, that indicates fault...

[Jimmy60]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

I have exactly the same problem and I have read through most all the posts for this model. My question is simple; Does the power supply board supply the 55V to Va and the 207V to Vs? Or are those voltages back fed from the Y-main and X-Main boards?
I was not getting any voltage on those test ports so I replaced the PCB. Guess what? Still don't get any voltage???

Thanks for your help.
Jim

[tom66]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

The power board supplies those voltages.
A short on the X- or Y-main will cause the voltages to go. Vs short will also take Va down.

[Jimmy60]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

The power board supplies those voltages.
A short on the X- or Y-main will cause the voltages to go. Vs short will also take Va down.

Thanks Tom for responding. I have the x and y-mains disconnected and still no voltage on Vs or Va? The only thing pluged in is the robbon to the main boord and the small ribbon to the control board. The relay goes click/clack once when the power button is hit on the remote, the red led turns blue and the sound comes on. The 5.3 volt and 15 volt checks ok. What am I doing wrong?
Thanks again for any help
Jim

[tw2005]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

Thanks Tom for responding. I have the x and y-mains disconnected and still no voltage on Vs or Va? The only thing pluged in is the robbon to the main boord and the small ribbon to the control board. The relay goes click/clack once when the power button is hit on the remote, the red led turns blue and the sound comes on. The 5.3 volt and 15 volt checks ok. What am I doing wrong?
Thanks again for any help
Jim

To my knowledge that TV is based on a Samsung panel , 42C450 and from I've read if either the x or y boards are disconnected it detects a fault and shuts those voltages down.

Copied from a fast track guide for a samsung


"Will not be run with the “X” or “Y” main disconnected. The SMPS will shut down immediately. However if a meter is first connected to the test point when power is applied it will read the correct voltage briefly before shut- ting down.(You have enough time to check key voltages)
CAUTION: Do not reconnect any connectors to SMPS or Y/X Boards until power has been turned off long enough for Vs to drop below 10V or damage will occur to X or Y Boards."

"“VITAL SIGNS”
When troubleshooting, It's very important to first check Vs, Va, Vsc & Ve
If Vs is missing (0V), disconnect power and check for short. Use ohm meter to measure resistance while disconnecting Y-Board & X-Board supply feeds one at a time.
Turn Power On and Test SMPS with short connector removed for correct Vs voltage verification. (It may only come up briefly but to full level). Again be careful not to reconnect Power Connectors until Vs falls below 10V.
If Va is low or missing, disconnect Supply Feed to Address Boards and
Check to see if SMPS Supply is restored. (Note Va feed normally passes through the Y-Drive to the Address Boards (Logic Buffer Boards).

If Vsc is low or missing and Vs was OK, the failure is with the Y-Board
since the Y-Board generate the Vsc voltage from the Vs supplied by the
SMPS.
If Ve is low or missing and Vs is OK, the failure is with the X-Board since the Ve is generated by the X-Board from the Vs supplied by the SMPS. Please note in some rare cases the Ve may be generated by the Y-Board feed to the X-Board.)"

[Jimmy60]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

Thanks TW;
That information was very helpful. I tried checking for shorts as the guide said but either I am not doing something right or there are no shorts. During all the testing and powering off and powering on the symptoms actually made a change though. Now when I power on I get a series of three clicks from the PSB.
Here are the voltage readings I got when powering up;
Va = 54v then falls off to 0v.
Vs = 207v then falls off to 0v.
Vse = 0V with x-main connected and three clicks
90V then falls off to 0v W/X-Main disconnected and only one click
VScan = 193V then falls off to 0v.

So this logically sais the X-main is the culprit!!!
Right???

[Jimmy60]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

Think I am going to replace both the x and y-main boards. Surely I'll get it then?

Thanks for everyone's help!!!

Jim

[Michale32086]

Re: RCA 42PA30RQ Playing The 'Let's Swap PCBs' Game

Jimmy60,

Did you have any luck with your TV???