Help with Panasonic TC-P42ST30 After Power Surge

[milkrocks]

First off, thanks for your help! I've been working with electronics for many years now but have limited tv repair experience. I was given a TC-P42ST30 that wouldn't turn on after a power surge. I've replace the main board and the power supply. The TV will now power on with either the new PS or the one that came with the TV. All functions of the TV work properly including menus and inputs. The sound work perfectly.

The problem is in the image. The image shown is consistent with the program but the picture quality is terrible. Dark portions are black, light portions are completely blown out. The power supply is putting out 214.9V.

I'm thinking of buying one or both sustain boards but am not sure if this would correct my problem. See attached for a low quality photo i took of the TV.

[tom66]

Re: Help with Panasonic TC-P42ST30 After Power Surge

I'm thinking 215V is far too high. The 12th gen Panasonic I'm working on (TC-P50G10B) uses 193V, and it's only a generation or two behind yours, I think. What does the panel sticker say? (usually handwritten calibration voltages.) Also, there are some adjustments on the SC board called Vad and Vscan. Both can affect the picture, so try adjusting them if you can, there are test points and the service manual will list the exact settings.

[tw2005]

Re: Help with Panasonic TC-P42ST30 After Power Surge

Which board is producing 215V,the original or the replacement? Are they both putting out the same Vsus?

From what you have written, it was the main that was toast? Was the replacement new or where did it come from. All the TV setup and data is on the EEPROM so if anyone has messed around in the service menu on that replacement board that also could upset the picture.

[milkrocks]

Re: Help with Panasonic TC-P42ST30 After Power Surge

Both boards produce 215V. I adjusted the voltage up and down a bit (for a very short period of time) and saw no difference in picture at 200V to 225V. The main board i purchased was from ebay - it seemed to be from a seller who parts plasmas that have been damaged in shipping.

[tw2005]

Re: Help with Panasonic TC-P42ST30 After Power Surge

Both boards produce 215V. I adjusted the voltage up and down a bit (for a very short period of time) and saw no difference in picture at 200V to 225V. The main board i purchased was from ebay - it seemed to be from a seller who parts plasmas that have been damaged in shipping.

That's strange, seems too high. I wonder how accurate your meter is then.
I can't really pick from the photo what the issue is though.

[N9ZN-Extra]

Re: Help with Panasonic TC-P42ST30 After Power Surge

I am having the exact same problem, power surge (lightning thru cable box), only the TV was affected everything else in house remained powered up including my computers. TV would not power on and the power light did NOT flash any sequence code and remained unlit when the power button was depressed.

I replaced the A Board with another A board purchased on E-Bay (board was out of a 65 inch TV) but part number was the same (TNPH0912 1A). Like you everything works but the picture looks identical to what you described and included a photo of.

I had been thinking the A board was from another model of TV, much larger size, and calibration was likely way off. My intentions have been going toward getting another A Board from the exact same TV that I am working on. Calibration should be much closer under those conditions and I hoped the picture problems would go away.

As it is I found this post prior to ordering another board and wanted to see what you finally didi to resolve your troubles. I BET YOUR SOLUTION will also be my solution. Could you share what you did to get things working correctly? I sure will appreciate it!

[N9ZN-Extra]

Re: Help with Panasonic TC-P42ST30 After Power Surge

Now that I am re-thinking things I am begining to think calibration is not the problem. Anyone have any thoughts that might lead me in the right direction?

The picture improves dramatically (85~90% good with hints of wash out while dark areas have become lighter) when I place a program into 2D to 3D translation.

I have the exact same model of TV as the OP, a Panasonic TC-P42ST30. Self check test of the TV all report back good for areas tested on the main board. Service Mode test screens look almost normal (graduated whites are not as pure as I think they should be) but I am not certain of what normal looks like, RGB colors are fine, and there are no distortions, lines or other distortions in test screens. I did notice the blue with white band around edges test screen also has a thin red band outside the white band, this is likely not normal.

I have the factory service manual for my Television if anyone needs to refer to it while helping. I can shareparts of it for that purpose, I think, unless that is not allowed in the forum.

[N9ZN-Extra]

Re: Help with Panasonic TC-P42ST30 After Power Surge

Tom66 mentioned in another thread that main boards from similar set with different size panels are not compatible. The only potential solution to this per Tom66 is to swap flash chips containing the boards plasma panel personality.

SOLUTION TO OP"S QUESTION:
First I must assume OP tried to repair his TV with a board from another size panel or of a Panasonic series other than ST30.

I had the exact same problems OP had from repairs made down to how the picture looked, bright wash out and dark areas darker using the main board from another larger panel TV although the board had the exact same Mfg. board number.

After Tom66's comment to me in another thread I ordered the correct main board for my TV model number, installed it, turned the set on, ran self test (all good), and the TV was in like new maybe better than new condition. Excellent picture now in 2D and 3D as well as 2D to 3D conversion.

After installing the correct main board I went thru looking at Vsus for any needed adjustment. I found a tiny bit of reason to make the Vsus adjustment from low to high but decided to leave it on low since differences were so very minimal and low is the factory default. Afterward I calibrated the picture (without a color analyzer) and now I have a better picture than before the set went out. Can't beat that for a result.

THANK YOU TOM66, credit goes where credit is due! The only thing I will calim credit for is wondering if the first main board was compatible. Fact is I was not sure and Tom66 gave me that answer.