Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

[rmacintosh]

I aquired this Panasonic 60" plasma around the time my first child was born. It was meant to be a project tv, hoping to fix it chipping away at the repair in my free time. Well that was 2 years ago and i'm really just getting around to making a sincere effort to see if I can ressurect this beast.



The symptoms of the tv ar as follows:

• Plug AC in to back of TV
• After about 2 seconds the relay on the P-sub board will click on and then a fraction of a second later it clicks back off
• The 3 blink code is given by the power LED
• If the TV is unplugged and then plugged back in the above process repeats ending with the 3 blink code

In my troubleshooting so far and based on documentation and research I feel the problem is isolated to the A-board. I would also characterize this 3 blink code as a 'fast' 3 blink code. I have read a few troubleshooting guides differentiating slightly in symptoms and root causes for the 3 blink vs fast 3 blink code.

It would seem that the 3 blink code is very sparsely documented and possibly one of the less common failure codes encountered.

Attached 4 pictures of my set.

1. The entire back of my set
2. A picture of my board suffix - I have read as UC
3. P-board (p/n: MPF6915)
4. A-board (i've removed the heatsink for better view) p/n: TNPH0988UC

What I have measured so far:

Connector P6 from p-board to a-board A6

F_STBY_ON
F15V
15Vc
15Vs
S0
S1
Panel_Main_ON
------ all above are 0v with set turned on blinking error code
When the relay first clicks for a split second then back off I can observe the F15V signal ramp up on my meter towards 15v but never gets there before the relays click off and back to 0v

STBY5V = 4.45v at all times
STBY5V_ON = 30mV or so. When I first plug the AC in it goes to 4.45v until the relay clicks on/off then down to 30mV

I have also been able to measure the 3.3v stby and 1.1v stby rail from IC5000 (analoc ASIC) to be both present reading 3.3v and 1.1v at all times.

I have measured around for shorts at all the regulators and can only seem to find 1 possible source for a short. IC8101 which generates the SUB1.5v rail. I am reading 56ohms on the output of the regulator. I am not sure if this might be the cause. I hastily removed the filter caps on the output thinking they may have been shorted but no go. This rail supplies all the DDR memory on the board as well as the PEAKS PRO4 chip.
Then I started thinking if this is a short at all, it is a fairly low voltage rail and wasnt sure if that was a normal impedance for DDR memory...i mean that voltage into 56ohms is just a mere 26-27mA. Nothing catastrophic.

[dick_barton]

Re: Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

With the set powered off and detached from wall socket use your meter set to ohms and measure the resistance fom VA to ground and VSC to ground.
The 1.5V @56 ohms is OK as you suggest.

[rmacintosh]

Re: Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

I measured both (Vsus - P11 & P2 connector, and Vsus - P35 connector) and they start out as a short and quickly resistance climbs to 40+ Mohm

If the TV is plugged in there is no voltage on either.

I'm using the service manual for the TV i found here: https://www.manualslib.com/manual/12...c-P60gt50.html

[rmacintosh]

Re: Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

My intent with this tv is, hopefully, to not only pinpoint the failure but to perform a component level repair to bring it back to life - if possible. I have found that a few of the boards are available from various sources but the A-board is pretty much unavailable everywhere besides eBay who have a select few for $250-350. That is way more than I am willing to spend.

[budwich]

Re: Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

I measured both (Vsus - P11 & P2 connector, and Vsus - P35 connector) and they start out as a short and quickly resistance climbs to 40+ Mohm

If the TV is plugged in there is no voltage on either.

I'm using the service manual for the TV i found here: https://www.manualslib.com/manual/12...c-P60gt50.html

Sorry if I am off base, but are you saying that if you unplug the connector from the power board to the SC ? board that you never get any voltages on the "disconnected" cable? even when you hold down the power button to force on the set?

[rmacintosh]

Re: Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

Sorry if I am off base, but are you saying that if you unplug the connector from the power board to the SC ? board that you never get any voltages on the "disconnected" cable? even when you hold down the power button to force on the set?

Not at all.

I have tried both scenarios. No voltage on Vsus (2 cables with Vsus and GND to the SC board and the SS board) or Vda (1 cable with Vda and GND to the C boards) with everything connected and AC plugged in. Also nothing if I try to power on the set with the power button or force on by holding the power button.

If I disconnect both the cables to the SC / SS boards and the C boards I still measure nothing on Vsus or Vda. At any point before, during or after AC is plugged in and/or the power button is pressed.

Attached board layout of my set.
Also attached wiring diagram showing connections from P-board to SC / SS / C boards and A-board.

[dick_barton]

Re: Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

I measured both (Vsus - P11 & P2 connector, and Vsus - P35 connector) and they start out as a short and quickly resistance climbs to 40+ Mohm

If the TV is plugged in there is no voltage on either.

I'm using the service manual for the TV i found here: https://www.manualslib.com/manual/12...c-P60gt50.html

Can you check Vda P35 for short as described earlier using your meter set to ohms

[rmacintosh]

Re: Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

Can you check Vda P35 for short as described earlier using your meter set to ohms

Sorry my bad,

I did the measurement, but my earlier response had a typo:

I measured both (Vsus - P11 & P2 connector, and Vda - P35 connector) and they start out as a short and quickly resistance climbs to 40+ Mohm

If the TV is plugged in there is no voltage on either.

I'm using the service manual for the TV i found here: https://www.manualslib.com/manual/12...c-P60gt50.html

So there seems to be no short, just what looks to be capacitor(s) charging through the meter as the resistance reading goes from short cct to open cct in a matter of a few seconds.

[budwich]

Re: Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

IF the blink code is pointing at 3.3 volt issues, then you may want to trace those area especially related to the A board. However, since you have checked for shorts, the problem maybe more to do with failure of continuity / broken trace / faulty component. Tracing back SOS logic back to chips that might be non-operational might be difficult... but you might get lucky.

[budwich]

Re: Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

Depending on how good your soldering is, you might consider changing out the IC (peaks?) as a possible effort..... since you appear to have checked a lot of the "sub paths" / voltages and they appear "good".

Further, I know there are lots of models and design differences but perhaps other guides will provide you with some useful ideas and directions even if you have to "adlib" or "translate" to something specific for your model. An example is this
https://www.manualslib.com/download/...Tc-P50s60.html
which provides more troubleshooting guidance and is in-line with many others out there.

[rmacintosh]

Re: Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

I did some digging for troubleshooting guides that had info on the 3 blink code as well as closely matched my set since I could not drum up any troubleshooting guide for my specific Plasma set (manufactured May 2012).

I came up with the following details:

Below, i have ruled out Vsus or Vda short circuits by measurement.
So that points more to P15V rail problem



Below picture, points again to P15V rail - this time more specific, shorted.

SUB3.3V rail is definitely missing...possibly shorted in some way or another - I have yet to do exhaustive probing on the A-board to rule it out.

SUB5V is definitely missing - but not indicating shorted. Something more to probe around on.



Another indication of 3-blink fast pointing to SUB3.3V issue missing or shorted.



This one has a reference to fast 3 blink code relating to an IROM error.
I have no idea what this means or what IROM refers to, and the document does not elaborate further on it.



There are also 2 attached 3 fast blink troubleshooting flowcharts that I drew my path through the chart for my symptoms, all ending on "Replace A-board"


Going to probe some more on the A-board around the P15V / F15V and SUB5V and SUB3.3V rails.

[rmacintosh]

Re: Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

Depending on how good your soldering is, you might consider changing out the IC (peaks?) as a possible effort..... since you appear to have checked a lot of the "sub paths" / voltages and they appear "good".

Further, I know there are lots of models and design differences but perhaps other guides will provide you with some useful ideas and directions even if you have to "adlib" or "translate" to something specific for your model. An example is this
https://www.manualslib.com/download/...Tc-P50s60.html
which provides more troubleshooting guidance and is in-line with many others out there.

I would consider my soldering abilities very capable. Granted I'd be able to source any of the ICs on this board I'm sure I could replace them. Maybe with the exception of the PEAKS PRO4 processor. I think I could reflow it if needed, but to reball a bag like that would be tough.

Attached picture of a-board. Red circled the regulators, yellow circled is the Analog ASIC chip that could be a potential culprit. The blue circled is the PEAKS PRO4 chip

[budwich]

Re: Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

didn't mean to cause you to "swirl" as it does appear you have done a lot and my experience is very limited with only working on panny plasma and even that resulted in an sc board replacement after significant time trying to replace components.

Having said that, you indicate a missing sub 3.3v rail. That is probably not good since that potentially drives some of the possibly responses that some of the monitoring chips operation either in terms of "state" or "drive levels".

With the work / tests that you have done I would have expected some form of operating voltages heading towards the SC at some point... maybe not "forever" but at least a "blip". This to me, means the system is stopping the power supply from turning on. I thought I saw some line that went from the A towards the power board (at least in the document link that I posted).

Have you tried unplugging the IR sensor board?

[budwich]

Re: Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

if I follow the sm manual that you posted for the set, ic8704 and ic8705 provide converson of the p15v voltage to the appropriate lower voltages on / in the A board.

[rmacintosh]

Re: Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

if I follow the sm manual that you posted for the set, ic8704 and ic8705 provide converson of the p15v voltage to the appropriate lower voltages on / in the A board.

Right.

I'm going to probe around those regulators, as well as monitor the DCDCEN pin of IC5000 (analog ASIC) to see if that chip is even telling the regulators to turn on. If this enable pin never tells these regulators to turn on I don't see any need to test these regulators or anything downstream of them. As in the pictures below, the DCDCEN pin from IC5000 controls the operation of IC8704, IC8705, IC8100, IC8101 which provide SUB5V, SUB3.3V, SUB1.5V, and SUB1.1V rails respectively.

[budwich]

Re: Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

yep, it is doubtful that the regulators are all bad, but a guick measure of the output will tell which or all are not there. As you indicate, moving to ic5000 and checking the incoming states on the error lines will likely tell you why the EN is not happening... or maybe it is but possibly a broken track close / at the chip is an issue..... or possibly the chip itself is faulty which also a good possibility especially since there appears to be some form of regulators built in to that chip... those could have had an impact on the overall "sanity" of the ic.

[rmacintosh]

Re: Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

I think I need an oscilloscope to probe some of the lines and voltages at turn on. Its too unclear what is going on using just a meter.

I was able to confirm the IC5000 is outputting a DCDCEN signal for all the regulators and each of the regulators appear to turn on and the voltage ramps up before the whole tv shuts down a split second later.

I put the meter on MAX voltage reading and a few of the rails would peak at around 9.5v but that might just be a spike at turn on. It would be nice to see what happens visually with an oscilloscope. The 1.1v rail spiked to 9v as well.

Haven't been able to find any shorts or open traces yet. If any of the regulators are bad I don't think ill be able to find replacements. They are all custom Panasonic stamped part numbers, nothing you can look up and buy on Digikey.

[budwich]

Re: Panasonic Plasma repair - TH-P60GT50 - Dead, 3 blink code

Not sure that a 1.1v rail should get to 9v ... might kick in some overvoltage protection. Yes a scope would probably help alot. Maybe you can borrow one from a someone?