Panasonic TH-P50X20

[Neelix]

I have TH-P50X20 TV that turns off with 7 flashes. I did the isolation test and measured resistances of the SD and SU boards. The resistances seem fine and with the SD and SU boards disconnected and SC50 shorted out, TV still turns off with 7 flashes. I turn TV on and measure voltages - VSUS is 191V, VAD is -0.8V, VSCN is 93V, P15 is 15V and P5 is 5V. After few seconds all voltages to SC board start to go down, relays click off and light flashes 7 times. With VAD being only -0.8V, that's where the fault must be. I measure all the transistors and diodes mounted against the heatsinks and don't measure any shorts. I look at the circuit diagram for the VAD voltage generator and it's mind boggling Any help with finding faulty parts in VAD circuit would be welcome. Partnumber of SC board is TNPA5063/2

[tw2005]

Re: Panasonic TH-P50X20

How are you checking for shorts? diode and/or resistance?

[tw2005]

Re: Panasonic TH-P50X20

I saw a repair kit for 7/10 blinks. says 22 parts, some as below

Panasonic Repair Kit contain 22pcs components.

Q401 Q402 Q421 Q422 Q660 Q661 Q452
D482 D422 D8XX D7XX? Q7XX AND Q7XX?
IC521 IC7XX IC7XX? PLUS SURFACE MOUNT DIODE AND RESISTORS.

Symtom; power LED blinks 7 & 10.

[tw2005]

Re: Panasonic TH-P50X20

also Vscn is out of range too, 125 - 166V, outside of that also triggers 7 blink

[tom66]

Re: Panasonic TH-P50X20

VSCN is usually wrt to VAD, low VAD can cause low VSCN.

[tw2005]

Re: Panasonic TH-P50X20

have you had a poke and checked any of these diodes for short

[tw2005]

Re: Panasonic TH-P50X20

Can you measure TP82-gnd resitance, resistance across C561, resistance at the pins marked IC771, SC2 resistance. If you can measure twice , once for each polarity of the probes.

Just looking for any clues of normal Sc failure, the SS in these also shorts although I 'd expect 4 or 10 blink

[Neelix]

Re: Panasonic TH-P50X20

Thanks tw2005. I'll do those measurements and reply with my findings when I'm done. I only tested the transistors and diodes using the diode function of my meter. I should have mentioned it, but there was actually transistors and diodes shorted on the SS board, which I replaced. One of the two boards must have caused parts to go faulty on the other one as well. I have a working SS board that I use for testing at the moment in the TV. I just hope the faulty SC board don't mess up my working SS board

[tw2005]

Re: Panasonic TH-P50X20

bad SS can take out the SC because of the ERC cct . The 42" has a SN board, but the cct will be pretty much the same. I expect there are some DG501 transistors and the SMD diodes associated with them short. I had a SS blow(after repair) which i repaired originally and i did something a bit daft , disconnected ss11 and left the SC3-SS3 connected, powered it up and blew the crap out of the SN.

D441, D451 come to mind

[Neelix]

Re: Panasonic TH-P50X20

I measured all diodes and transistors mounted to the heatsinks again as well as the diodes you encircled. The next ones measure short, but they are still soldered onto the board

D16481
Q16451
D16451
D16503
Q16661
D16672
D16670

So there's a short in the VRL circuit and a short between VAD and VFG. Next is the resistance measurements you wanted me to make:

TP82
3.79K - black probe GND and red probe TP82
1.57K - black probe TP82 and red probe GND

C56
5.6K - both directions

SC2
1.65M - black probe GND and red probe VSUS
-1.24M - black probe VSUS and red probe GND

IC771
Resistance starts in the Mohms range and then just continously drops

[tw2005]

Re: Panasonic TH-P50X20

I measured all diodes and transistors mounted to the heatsinks again as well as the diodes you encircled. The next ones measure short, but they are still soldered onto the board

D16481
Q16451
D16451
D16503
Q16661
D16672
D16670

So there's a short in the VRL circuit and a short between VAD and VFG. Next is the resistance measurements you wanted me to make:

TP82
3.79K - black probe GND and red probe TP82
1.57K - black probe TP82 and red probe GND

C56
5.6K - both directions

SC2
1.65M - black probe GND and red probe VSUS
-1.24M - black probe VSUS and red probe GND

IC771
Resistance starts in the Mohms range and then just continously drops

"I measure all the transistors and diodes mounted against the heatsinks and don't measure any shorts. "

Does not match up now second time around?


TP82
3.79K - black probe GND and red probe TP82
1.57K - black probe TP82 and red probe GND

This seems normal, that's the 15v line and feed the FET driver IC521

C56
5.6K - both directions

This is the 5V line and is what I expected

SC2
1.65M - black probe GND and red probe VSUS
-1.24M - black probe VSUS and red probe GND

This I get over 3 meg, the negative you have is because the cct charged, you'd have to short those pins then measure reversed but I'm calling this lower than normal but I have a fluke meter and so hard to judge but I feel this is sus which ypou'd expet if part of the cct is shorted out.

IC771
Resistance starts in the Mohms range and then just continously

This one is strange, this is the 5v reg that powers IC773, normally with a shorted Q661, IC773 and surrounding parts(look at the schematic) are bad and you'd see low ohm short, say 3-5ohms.

But what you quote also seems wrong as 5.7-6.1k would be expected in cct.
i don't have time at the moment to analyse the rest till I get home from work.

If you could associate parts with the locations to help me out get a feel of what's fitted. I'll have to check that the TNPA5066 cct and 5063 are the same(or very close before I can be 100% about IC771, I think it's sus at this stage.

Could you recheck this and /or go to IC773 and measure pin 5-3

[Neelix]

Re: Panasonic TH-P50X20

I noticed that the tips of my meter probes don't seem to make contact so well anymore. I replaced the probes and measured everything over again

D16481, Q16451, D16451, D16503, Q16661, D16672 and D16670 still measure short

Resistances of TP82 and C56 same as before

SC2 - I shorted out the two pins before measuring in the reverse direction
2.02M - black probe GND and red probe VSUS
-1.4m - black probe VSUS and red probe GND

IC771 - I misunderstood the first time and measured the resistance between the pins you encircled and GND, instead of the resistance between the two pins
2.9K - black probe pin 1 and red probe pin 2
3.7K - black probe pin 2 and red probe pin 1

[tw2005]

Re: Panasonic TH-P50X20

Well you're going to have to remove parts to figure out what's bad. IC771 is wrong.

Check Q818,701,702. Personally i would replace IC773,Q701,702,818,661, check D702 then recheck Vout -gnd IC771

Watch out for low resistance on the IGBTs, some don't go dead short may be in hundreds of ohms, like 30F125, I think this board has that one.

D16481, D16503, Q16661, D16672 and D16670 - probably just pull these out and check

Q16451, D16451, - I would remove D451, check it and recheck the transistor

have you repaired a Sc before?

[Neelix]

Re: Panasonic TH-P50X20

Thanks very much tw2005 for all your advice I'll start to remove the parts that measured short and measure them again out of circuit, measure other parts and see what I get. Would have been nice though if I had a working board to compare with. I repaired a few SC boards before, but the SC boards in the later models I'm not having much success with

[tw2005]

Re: Panasonic TH-P50X20

Thanks very much tw2005 for all your advice I'll start to remove the parts that measured short and measure them again out of circuit, measure other parts and see what I get. Would have been nice though if I had a working board to compare with. I repaired a few SC boards before, but the SC boards in the later models I'm not having much success with

Yeah, can be frustrating but from what I see a TNPA5066 is equivalent cct so I'll have that to reference to.

I know on that one(I've done 2) and it took me a couple of goes I can see I've replaced

Q661 RJP63F3A
Q401,402 RJP56F4A
Q621 , 30F125
Q421, RJP43F4A
D641, ? Replaced but I used FN25TM4SW
D481, ? Replaced but I used FN25TM4SW
Q451, DG501RP
D451,441
ic501,521 not touched but not a bad idea to replace them
PC561 opto, I have had to replace but after I blew this board up

Q701,702,818 I've replaced

IC773
R707 I've replaced looks like another casualty of my first failed repair

IC771 , I've either pulled it for testing or rplaced, can't tell which.

[MOSFET606]

Re: Panasonic TH-P50X20

Hi, I'v been working on the Sanyo variant of this TV, I'v found a few shorted chips and replaced them,

But now the D451 smt diode that says K606 on it, is shorted...

I cant find this part anywhere, Does anyone know the part number to this diode, Or a schematic for the actual SS board...

All i can find is service manuals with main board schematics...

D451 - ?

[tw2005]

Re: Panasonic TH-P50X20

Marking is K6, D1FK60-5073 600V 0.8 amp , super fast recovery diode

http://au.mouser.com/ProductDetail/S...xWMMsAxA%3D%3D

[MOSFET606]

Re: Panasonic TH-P50X20

And you 100% certain this is the exact one?


just want to be sure

[MOSFET606]

Re: Panasonic TH-P50X20

Nvm thats good enough, i appreciate the fast reply

I got it now, K6 is type, 06 is date code..

Awesome i tried finding this information but wasnt easy or clear as this datasheet

Thank you!

[MOSFET606]

Re: Panasonic TH-P50X20

Is there a substitute on mouser for the

Q661 - RJP63F3A On SC board


Ebay says its a mosfet, and rens... data sheet says its an IGBT which it is an IGBT


The shipping on mouser is killing me already at $30... and if im going to order from them i might as well get aleast $5-10 in parts ...

I did some filtering and didnt find any that were rated 630V Collector to emitter voltage