Re: Panasonic P50ST50H - No power - HELP please
OK, I am not sure what happened...
I was following the flow-chart on P.30 of the Troubleshooting Guide (attached).
I disconnected A1 on the A-board as instructed. TV still not on, so it seemed I need to replace the A-board. However, that is now unnecessary.
As I reconnect A1 and everything else just to re-check the whole troubleshooting procedure, I was very surprised to see the front LED in solid red when I switch the TV on. There is still no image or sound.
As I thought...
BEpsilon
Member
Last Activity: 11-01-2021, 05:29 AM
Joined: 12-25-2019
Location: Hong Kong
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Re: Panasonic P50ST50H - No power - HELP please
3.3k 2W Resistor has been replaced.
As one can see from the attached image, the old resistor has no resistance whatsoever. I wonder if the resistor was damaged due to external factor(s) or preexisting defect.
Now when AC power is provided, but no other boards attached, I can see +4.5 V DC at Pin06(STB5V) of Connector P6.
+4.5 V DC is also on J62 ("5V" printed on the board). There is +15.75 V on J76, which is right next to J62.
With all the other boards back with...Last edited by BEpsilon; 01-11-2020, 05:31 AM.Leave a comment:
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Re: Panasonic P50ST50H - No power - HELP please
I will go visit a local electronics components store to get a new resistor.
Lets hope a new resistor is all it needs.
I will let you (and everyone reading this) know the outcome.
Thanks.
Assuming the resistor is all it needs, I wonder if there is any preventive maintenance a professional like yourself would recommend me do please?
From my research so far, I have read about loose mounting screws causing arcing and component failure eventually. ...Last edited by BEpsilon; 01-09-2020, 02:53 AM.Leave a comment:
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Re: Panasonic P50ST50H - No power - HELP please
Thank you very much for all your guidance so far.
So, at this point, just replace that single 3.3k 2-watt resistor?
Should I replace any electrolytic capacitors (even-though they're Rubycons and visibly in good shape)?
There are two 35V 47uF in the area, so I thought I would replace them with 50V 47uF? May be Panasonic FC/FM capacitors?...Last edited by BEpsilon; 01-08-2020, 11:30 AM.Leave a comment:
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Re: Panasonic P50ST50H - No power - HELP please
Thanks for waiting:
R147 = 0.999 kΩ
R148 = 24.36 MΩ
IC200 (34A65, NCP1234), Pin8(HV) & Pin4(Gnd) = 375.2 kΩ (Positive probe on Pin4, Negative probe on Pin8)
IC200 (34A65, NCP1234), Pin8(HV) & Pin4(Gnd) = 24.8X MΩ (Positive probe on Pin8, Negative probe on Pin4)...Last edited by BEpsilon; 01-08-2020, 11:14 AM.Leave a comment:
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Re: Panasonic P50ST50H - No power - HELP please
Wow! Man that's amazing.
Indeed, IC200 is a "34A65", as shown in the attached photo (sorry about the flash).
Image of NCP1234AD65R2G on Digikey looks identical to what is on the board.
I will go check the resistors as you suggested....Leave a comment:
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Re: Panasonic P50ST50H - No power - HELP please
I will go and disassemble the P board from the TV and check for you.
Please standby. Thanks.
Prior to reading your reply, I was checking the MOSFET with my multi-meter... the readings I see are weird to me (not sure if I am wrong or not).
Obviously, Q110 is under a heatsink, so I cannot identify its specs. All I can see are the 3 terminals - Gate, Drain, Source (as labelled on the board).
I am new to this, so I browsed a few webpages on how to test MOSFETs with...Last edited by BEpsilon; 01-08-2020, 10:08 AM.Leave a comment:
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Re: Panasonic P50ST50H - No power - HELP please
Understood.
Negative probe of multi-meter clipped to the negative terminal of C130 (bottom one of the 3 high-voltage 450V 100uF capacitors).
TV plugged into power outlet.
On R224, both left (towards capacitors) side and right (towards heatsink) side are +311.X to +312.X V DC.
On R148, left side is approx. +311.3 V DC and right side is approx. +1.88 V DC.
On J4, reading is approx. +311.5 V DC.
I indeed have more...Last edited by BEpsilon; 01-08-2020, 02:03 AM.Leave a comment:
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Re: Panasonic P50ST50H - No power - HELP please
I checked the [URL="https://en.wikipedia.org/wiki/IEC_60320#C13/C14_coupler"]C13 plug[/URL] at the end of the power cord that came with the TV. This rules out a damaged cord.
I then checked the two-pin AC input connector on the power supply board. This connector (mounted at an angle) is downstream from the AC filter module. I see full AC mains voltage on the live and neutral pins.Re: Panasonic P50ST50H - No power - HELP please
I checked the [URL="https://en.wikipedia.org/wiki/IEC_60320#C13/C14_coupler"]C13...Last edited by BEpsilon; 01-07-2020, 06:19 AM.Leave a comment:
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Re: Panasonic P50ST50H - No power - HELP please
Thanks for your advice. I just checked that white component with a multi-meter. Results are in the attached image.
I have not removed any of the heatsinks yet. Lets hope the failed component(s) won't be SMD ones...
As an [b]update[/b], since this is "badcaps" forum, I measured the voltage at the positive legs of most of the electrolytic capacitors.
Just a quick check to see if part of whole power supply works I guess. Results are in the attached image....Last edited by BEpsilon; 01-07-2020, 06:23 AM.Leave a comment:
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Panasonic P50ST50H - No power - HELP please
Hello everyone
As you can see from my profile, I am a total newbie when it comes to TV troubleshooting or repairs.
Patient is a [B]Panasonic TH-P50ST50H[/B] Plasma TV, which was purchased new back in 2013. This TV runs on 220-240V AC (Hong Kong market).
I was doing some cable management and cleaning over the Christmas holidays (Merry Christmas everyone), so I decided to disconnect power to TV/STB right at the power bar (surge protected).
As luck would have it, the TV can no longer turn on when I restore power to everything. TV was running... -
Re: New Members - please post your introductions here
Hello everyone
First of all, Merry Christmas to you all.
A tinkerer who is interested in IT/mechatronics/automotive/aviation field.
Fixing things is part of my hobby. During my search for solutions, I come across this wonderful forum, so here I am - my 1st post.
Looking forward to learning more. Thank you.
Cheers!Leave a comment:
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