Panasonic TX-P50VT30B - 7 Flash issue.

[Turnip]

Hi folks,

Have one in where I get initial Green flashes then 7 Red flashes, no picture or sound.

Any thoughts ?  - Thanks -  Chris

[downunder]

Hi Chris,

Code 7 is the SC board (Y-sus), or SU/SD boards (buffers). If you read a short across the 2 pin plug SC2, you have a short on the SC board,
usually a number of FETs.

Alternatively, disconnect the SU/SD boards totally from the SC so that there is no longer any electrical connection to the SC board. Leave the SU/SD
connected to the panel ie don't disconnect the brown flexies that go to the panel.

On the buffer side of the SC, locate a small 2 pin socket SC50 and short out the 2 pins. Power the TV on. If still code 7, the SC is faulty. If the TV powers up to a solid green LED, SC is OK but one or both of the buffers are cactus. See how you go to this point.

Bruce

[Turnip]

Thanks Bruce,

Seems I've got a few duff Fets on the SC board. Note a repair kit on Ebay for £20 or a working board for £150.

Wondered if the buffers K.O. the SC (Seen no signs of burning on the buffers - £35 pair)

Replacing the Fets looks straight forward but seems the kit also contains a chip or two, what do you think ? - Thanks - Chris.

[downunder]

Hi Chris,

Kits are a bit iffey and often result in repeat failure. Suspect some of the FETs are clones and not ridgey-dig. I've always gone for board replacement but

they may be getting a bit scarce. Usually the buffers are OK. The metal pads under the larger screws that bolt the buffers to the SC are the floating

earth. An analogue meter (because it reacts faster than a digital one) on ohms is best.

Probe on floating earth, then run the other probe along the contacts of flexies that connect to the panel. Reads like a diode, so select

meter polarity for the high reading. All flexie contacts should read high. If not, one or more buffer chips are shorted.             

The SC often fails because of poor earthing between the board and the metal panel back at the mounting screws. Look for signs of arcing at these points

if you remove the SC and take remedial action. Pana supply screws with star washers now but I'm sure you'll figure out a solution.

Bruce

[Turnip]

Hi Bruce, thanks a lot.

Cust has donated the set as panel repair dubious (Judging by on line observations where half an hour is pretty good 'till the Fets go phut again)

Checked buffers as suggested - seem OK, so worth having a go as not much to lose and fun if it works -  Chris

Had a look at those fixing screw earths under the panel and found several dubious - Star washers for me.

[downunder]

Hi Chris,

You must have put a hex on me. A TH-P50ST30A plasma just wandered into my workshop with code 7. Five of the screw holes had been arcing and the SC board is cactus. Found around 5 shorted FETs. I have a donor board so I'll try to refurb it if I can't find a reasonably priced replacement.

Bruce

[Turnip]

Hi Bruce,

Checked about for kits and got the Ebay one for £20 inc. Other folks do a more comprehensive kit featuring bits which appear OK on my board - Guess the genuine Pana Kit.

Ebay kit
D401 (RF1501) D421 (DAF30a)  Q401 (30F131)  Q402 (30F131)  Q403 (30F131)
Q421 (RJP30H2A)  Q422 (RJP30H2A)  Q423 (RJP30H2A)  Q531 (B1HFPFA00001)  IC502 (COZBZ0001822)

Suspect as you said, good chassis connection is the biz - Good luck - Chris.

[downunder]

Hi Chris,

So today I took the bull by the horns. Found Q401, Q422, Q423 and D401 shorted, so I transferred them from a donor board I had (to avoid cheap underrated fakes. Cleaned up the screw holes and gingerly turned the TV on. Code 7 was replaced with code 8 (SS board). Found Q102 (RCJ330) shorted on the SS board. New FET and away it went. Ran it for a day all OK. Out of interest I checked a second SC board I had, but alas, it had 6 X 30F131s  and 2 X Diodes short, almost all the semis down the entire centre strip. Don't fancy my chances.

Bruce

[Turnip]

Hi Bruce, well done.

Took me a week to get around replace the bits, especially that tiny chip and dual transistor thingy, as eyes aren't what they were in the 70s.

Eventually after checking everything at least twice, cleaned up the 'earths' and fitted star washers as suggested - Powered up - Success (For the moment)

As set was a wall mounted gift, think run it for a month at least before I try Ebay for the stand.

Great fun - Chris.

[downunder]

Bravo, Chris. You're a Legend in your own lunchtime. You could start a nice little earner refurbishing these for other punters.

Who was your kit supplier?                            Bruce

[Turnip]

Hi Bruce,

Note it's a common issue where mended boards go for £150 a pop, and there are duff ones for folks who want to try their iron.

Suspect though that 'Pop' is the word. Can imagine 'Plasma' folk fitting repaired ones with maybe just two screws to hold 'em in whilst pouring a beer.

Could be wrong but suspect 'Plasma' people are just a bit different from LCD folks who count the cost of buying and using television.

Out - Presumably fed - Chap below gives 5 free 30F131 extra with every order - 'For next time'

microtechservice@hotmail.com

[downunder]

Hi Chris,

Tried my hand at another SC board today using FETs from a donor board. To remove the good FETs for transplant, I snipped the 2 legs then used an iron to heat the back plate till it came away. Unfortunately, most of them were open after I detached them, so I couldn't use them. Looks like it's off to ebay for kits so that one doesn't have to desolder them to start with. Such is life.  -  Bruce

[Turnip]

Hi Bruce,

Many times tried solder-wick then tried lift legs just a micron to get Fets off the board. Hardy ever works as encapsulating plastic seems tired by thermal recycling and they fall to bits.

Suspect your SC board Fets are IGBTs - A certain Ebay supplier provides several free ones with the basic kit for only £20.00.

They also seem to do AS15-XX chip replacements for £15.00 return post paid - Chris.

[downunder]

Hi Chris,

Couldn't track down your supplier so I ordered 25 assorted SC parts for around 15 AUD from Aliexpress - cheap as chips, so I hope they're not duds. - Bruce