samsung PS42C450B1WXXU

[lakey35]

Re: samsung PS42C450B1WXXU

accidentally caught the on button, tv came on but have a band down center of screen with just random white dots

[tom66]

Re: samsung PS42C450B1WXXU

Hopefully you just have a loose X connector. Post a picture of the bottom of the TV, there should be a board there.

It could also be a bad panel. Did it have the problem before the fault happened?

[lakey35]

Re: samsung PS42C450B1WXXU

you were right i dismantled the metal casing at bottom of tv and instantly saw one of the connector locks sitting upright, pushed it back down and hey presto fully working. Many thanks for all your help.

[tom66]

Re: samsung PS42C450B1WXXU

you were right i dismantled the metal casing at bottom of tv and instantly saw one of the connector locks sitting upright, pushed it back down and hey presto fully working. Many thanks for all your help.

Good to hear! Not sure how you fixed the Y sustain problem but enjoy your TV .

[lakey35]

Re: samsung PS42C450B1WXXU

I replaced the y sustain board with one i bought fully tested for £15.
Bargain repair, once again many thanks.

[PowerAmpFreak]

Re: samsung PS42C450B1WXXU

Hello! Did you note how the LED on the logic board was blinking during your troubleshooting? I have a similair set (PS42C455) which has very similair problem as you had, the VA and VS supplies starts up but is shutdown after a second or two.
In my case, the led is blinking very slow, but tom66 (thanks Tom!) informed me that this led should blink much faster if everything's ok. Maybe there is a fault in my Y-sustain board after all. I checked all the power components and everything measures fine.
Lakey35: You did try to disconnect the powerconnector to the Y-sus board, and still the VA and VS supplies did shutdown, right? Then it seems there is some kind of feedback to control board which activates screen protection and shuts down VA and VS.

[capkid]

Re: samsung PS42C450B1WXXU

I have an Insignia plasma TV (NS-42P650A11), which I'm guessing is a similar or rebadged version of this Samsung TV. I replaced shorted components on the Y-Sus, but it appears that the components failed after I turned on the TV. I then purchased a Y-Sus, since they're so cheap, but that didn't solve the issue, either. I haven't examined the replacement Y-Sus to see if it also has failed components, so that's my next step. I'm starting to believe that the buffer board is bad, because I read that bad Samsung buffer boards can kill the Y-Sus. Thoughts?

Edit: I forgot to mention that I also replaced the Z-Sus.

[capkid]

Re: samsung PS42C450B1WXXU

As a follow-up to my Insignia TV failure that appears to now be resolved, I found the following issues:

- Two bad IGBTs on the Z-Sus
- Three bad IGBTs and a bad diode on the Y-Sus

All the above components were on the large heatsinks. I also replaced the Y-buffer board, just in case.

[tom66]

Re: samsung PS42C450B1WXXU

It seems the new sets can blow both the X-main and Y-main at the same time in certain failures.

[capkid]

Re: samsung PS42C450B1WXXU

It seems the new sets can blow both the X-main and Y-main at the same time in certain failures.

Yeah, I didn't catch the X-main failure in the beginning, since the Y-Sus was also failing and I'm used to the Y-Sus being the reason for "no picture" failures in most plasma TVs I've repaired. Also, the X-main is hooked in series with the Y-Sus, so that tripped me up. I repaired or replaced the Y-Sus a couple times before I found the X-main issue

[capkid]

Re: samsung PS42C450B1WXXU

How would you recommend I reattach these pieces to the sustain boards? It looks like double-sided tape of some kind was used originally. I have some Momentive RTV, but I don't want to unnecessarily make a mess if there's a better way.

[tom66]

Re: samsung PS42C450B1WXXU

I'd try re-using double sided tape

[capkid]

Re: samsung PS42C450B1WXXU

I'd try re-using double sided tape

Ok. I was concerned about whether the tape originally used has properties that make it unique for use with electronics. If any similar double-sided tape will work, great.

[tom66]

Re: samsung PS42C450B1WXXU

I think it's supposed to stop the board from flexing and touching the panel, causing a short.

[capkid]

Re: samsung PS42C450B1WXXU

I think it's supposed to stop the board from flexing and touching the panel, causing a short.

Ok, thanks.

[capkid]

Re: samsung PS42C450B1WXXU

Ok, do you know which component(s) on the buffer board fails in these TVs? I was going to test it, but a new board was only $15 new on eBay from a reputable seller I've used in the past. So, I just ordered the whole board. I'm still curious, and I may test it later.

The reason for the above question is that I took a VERY wild swing and installed my good Y-Sus from the Insignia into a 42C450B1D I just picked up today; the Y-sus blew immediately when the buffer board was connected

(1) The Y-Sus was fine when it was connected to the power supply without being connected to the buffer. Once I connected the buffer - POOF!
(2) I left the Z-Sus disconnected when I installed the Y-Sus. BTW, the Z-Sus's components seem to check out fine in this TV.

[tom66]

Re: samsung PS42C450B1WXXU

See this video for how to test a buffer board.
http://www.youtube.com/watch?v=51SZsfH60EY

[capkid]

Re: samsung PS42C450B1WXXU

See this video for how to test a buffer board.
http://www.youtube.com/watch?v=51SZsfH60EY

I'd seen a similar test for other Samsung boards online, so I'd already tried that. I didn't find any issues, and there's no physical evidence of blown buffer ICs. I was thinking that maybe one of the other components, whose failure I wasn't sure would be evident under this test (resistor, diode, cap, voltage regulator, etc), might have an issue.

[tom66]

Re: samsung PS42C450B1WXXU

Was the control board exactly the same between the sets? Incorrect firmware could cause the damage. Shorted outputs (to either node) or shorts from IN to GND are the two major failure modes of the buffer boards.

[capkid]

Re: samsung PS42C450B1WXXU

Was the control board exactly the same between the sets? Incorrect firmware could cause the damage. Shorted outputs (to either node) or shorts from IN to GND are the two major failure modes of the buffer boards.

Yes, the two logic control boards are exactly the same. They have the same rev code and date, also.