Dp50719

[Nick's Tvs]

TV clicks on, and tries to turn on for about 5 seconds, then shuts off.
If you try to do this 3 times in a row, it will go into protective mode and you have to unplug the set for about 20 to 30 minutes before you can attempt again. It never shows any picture and always shuts back off after 5 seconds.
Main board was sent for testing, and is good. Power supply never produces VS or VA voltage, however I have no idea how to bypass all that stuff to isolate it.
I do believe I have a bad SC board and maybe a bad SS board.

SC board TNPA4848AG
D421 the legs labeled A are shorted to ground. Noticed IC521 had 1/3rd of its legs shorted to ground, but IC501 had none. They are the same IC just in different locations, so I think something is wrong there.
IC561 has pin 1, 10, and 19 shorted to ground but IC562 only has pin 10 shorted to ground. Once again same IC's just different locations, so I think something is going on there as well.
If I am correct in assuming these IC's are supposed to have the same readings, then which ones of these are good and which ones are bad? I checked my SS board TNPA4774AG and it has the same 2 IC's only this board only has one of each and both of them are registering the same shorts as the ones on the SC with shorts. So does that mean the IC's on my SS board are bad as well or that the IC's on my SC board that do not have the shorts are burnt and not having proper connection?

Any help would help. I did not get the part numbers of the IC's but if needed I can get that for you guys.

Also pictures are not posting for some reason, I will try again in a bit.

[Nick's Tvs]

Re: Dp50719

pics attached

[tw2005]

Re: Dp50719

the panel boards in this are the same as a panasonic 50px14 . So if you get that manual you'd at least get some schematics on the sc, ss boards and know what you're looking at.

yes you are correct,

d421 anodes are shorted to ground.
ic521 has 5 legs tied to chassis gnd
ic501 has none to chassis but does have a gnd ref which would be floating gnd

ic561 1,10,19 are tied to gnd
ic562 10 is gnd

I would scrap all current fault finding on these boards and start a fresh with a schematic.

Identify p5v, p15v and vsus on the sc and check resistance, may give some clues. SC 2 can be in the hundreds of Kohms to meg.

Another simple thing would be to identify the FETs and IGBTs on these boards and check them for short and low resistance as that would be the most common fail points and easiest to identify rather than trying to guess what should be on those ICs you mentioned.

[tw2005]

Re: Dp50719

I was just looking at the setup of this and was wondering if there is a way to force the P board on and have the panel lit. In some of the older panasonics including 2009 models you could remove 3 leads and it would fire up automatically producing a white panel.

So while I was trying to find a SM for this TV I stumbled across a service bulletin which describes how to check this Tv out when the green led fails to remain on.

You may already have it but I've attached it.

[Nick's Tvs]

Re: Dp50719

tw2005
Thank you for helping me out on this one.
I actually have not come across the service bulletin you attached.
Just printed it up and will be bringing it to the shop and will let you know what I find.
I do find it weird that the same pins on the exact same IC would go to one ground and floating ground on the other.
Why is that? Some sort of damage reduction technique if something gets screwed up?

[tw2005]

Re: Dp50719

tw2005
Thank you for helping me out on this one.
I actually have not come across the service bulletin you attached.
Just printed it up and will be bringing it to the shop and will let you know what I find.
I do find it weird that the same pins on the exact same IC would go to one ground and floating ground on the other.
Why is that? Some sort of damage reduction technique if something gets screwed up?

no idea why, simply I just accept this is the design.

Both of those ICs are the FET drivers.

If it was a panasonic we'd have a clearer idea on what is faulted due to the onboard diagnostic codes.

If you had a working TC-50PX14 TC-P50C1 TC-P50X1 around you could swap boards in and see what happens.

There's still plenty of SC boards available at SJ ,so that may indicate SC failure is not that common. In fact they have heaps of all boards except

the power board and the main board. maybe that's a clue.

Did a quick search on the other models, not much history there either except what may have been bad buffer board.

That leads me to another idea. On the panasonics the sd/su can be isolated (Vfg bolts need to be removed as well) then the small SC50 connector those 2 pins are shorted together. This completes the cct on Vfg which is monitored to indicate a buffer board is disconnected.

This is useful if the TV had a 7 blink code which can be sd/su/sc.

But since this TV done not have that ability to blink codes, you could take a punt and try it anyway just in case bad buffers are shutting this TV off.

From what you've written, the only board found good was the mainboard. I'd also try disconnecting SC2 and SS11 and back probing the Vsus at the P board and attempt to turn the tv on and see if you can see it momentarily. the other voltages too like the 15v and 5V lines .

Did not find enough history on any of the panasonic models or searching the SC board number here either .

[Nick's Tvs]

Re: Dp50719

Ok so I went through the process of checking shorts to ground on certain pins on psb, ss and sc. Since I didn't find any and I still get 0voltage out of vs and va, its stating that the problem is coming from the psb.
Just ordered it and will be hoping for the best.
Will keep you updated.
Thanks

[Nick's Tvs]

Re: Dp50719

Received the power supply and no difference. I do believe I may have received a bad SMPS however but I would like to confirm with someone first.

Ok so following the service bulletin.
This is with all original boards. Not that it matters since both SMPS give me the exact same results anyway.
A) unplugged the LVDS cable from main to D board. It says the SMPS should power up automatically. But I get nothing. It says if the tv stays on then main is fine, if the tv powers on and then back down, then main is probably the issue. But I don't get anything to power on.
Then I moved to b just to be thorough. I get no shorts on any of the pins. The closest I get is like 4k ohms. I also never get any voltage out of any of the pins.
I then go to page 2 where it says if you believe SMPS is defective.
I disconnected all cables from it except P25 as mentioned, and also disconnected every ribbon from the D board. The SMPS still does not turn on.
Am I doing something wrong? Is there something I am missing possibly?
Thanks for helping.
Also One last thing, is I ordered the LSEP1279HN and my original board was an LSEP1279WM but shopjimmy does state that they are compatible.

[tw2005]

Re: Dp50719

One thing it does not cover is what if it's a faulty D-board?

[Nick's Tvs]

Re: Dp50719

Yeah I noticed that as well and assumed it is because it very rarely failed. But I will do a basic check on the components on the SMPS and if I don't find anything funny will proceed to buying that D board unless anyone else has another test and or suggestion.
Will keep yall updated.
Thanks for the help tw2005

-Nick