Help diagnosing black screen Panasonic TC-P60ZT60
Hello to all, how have I not stumbled onto this excellent community in the past? I'm an engineer by trade, been hacking/repairing electronics since before I can remember ... sometimes to my parents annoyance 
Now I'm older and grayer and trying to kindle that "can do" mentality in my kids! so....
Our Panny TC-P60ZT60 went black screen while my daughter was watching. I began with an appropriate amount of cursing HDMI and modern electronics is general, until my daughter reminded me that I design modern electronics. Moving on, I tried the unplug, factory reset, etc, eventually I decided this is probably really broken. It's 7 years old, it's been worked pretty hard in our family of 5 ... but it's a beautiful TV, and I'm not ready to scrap it.
Due to marital factors, I'd very much like to take this thing off the wall, do my thing, and get it back up. If I can get to 90% certainty which part(s) needs replacing, I will pre-order, and hope to fix it within a day. Getting the TV off the wall means getting someone to help, and having it down means an ugly recessed area with cables etc right in the living room. First world problems, I know. I realize this plan has a significant chance of failing, but one can dream.
I have the service manual (from another thread here). I believe the problem is a bad main (A) board. The following are my data points:
1. It shows the "studio master" splash screen perfectly
2. No blinking red light
3. It doesn't show any menu's (or anything), but responds to remote pushes with the sounds I expect from navigating menus
4. ONCE, after leaving unplugged for a day, it worked fine until it was next shut off.
The above lead me to believe it can't be panel, buffers, etc (cuz I get splash screen). It can't be tuner, HDMI, etc, because even menus don't come up. It's not a "hard fail" because once it did come back. It doesn't FEEL like a bad cable anywhere but I'm less confident about that.
I'm guessing bad solder joint, or bad cap, on the main (A) board.
If folks agree with that diagnosis, my plan would be to order the part in advance. When the TV is down, giving it a dusting, alcohol cleaning the connectors. I'd rather avoid swapping a board if a cleaning is all she needs. But if that doesn't fix it, and I don't think it will, replace the main board. If THAT doesn't fix it, update my will, consider skipping town, look for bad caps to see if there's anything else I can replace (I have a decent spare parts pile), measure whatever voltages I can find for clues, take pictures, etc.
My questions are:
A) am I right that it sounds like Main (A) board? (TXN/A1UVUUS)
B) what are some recommended places to find that in 2021? I've seen it on eBay (~$244) but it was out of stock at the couple of parts sites I tried
C) most of my diagnosis hinges on the assumption that the splash screen is driven from the Main board, and isn't embedded in some other board or the panel itself, is that a good assumption?
D) if my symptoms ring any bells, would love to hear your story
To be real specific, my theory is that the splash screen is coming from one of the chips downstream from the main PEAKS-PRO4 chip (two downstream chips have Flash). The audio comes direct from that PEAKS-PRO4, but video goes through a "GCX" chip (with Flash and DDR3) sitting between PEAKS-PRO4 and another Flash-equipped "PD6H" chip that drives most of the video cables to the sub-boards. So looking at block diagram and my symptoms, I'm thinking it maybe a GCX chip failure (if PD6H drives splash screen) .. or .. link between PEAKS and GCX (if GCX drives splash screen) ... or something else interacting weirdly; hard to say. But looking at the block diagram, it seems pretty sure that the issue must be in the Main (A) board, right??
I have attached the service docs I found in other threads, for anyone that wants to look, or future like minded folks who stumble on this thread.
Now I'm older and grayer and trying to kindle that "can do" mentality in my kids! so.... Our Panny TC-P60ZT60 went black screen while my daughter was watching. I began with an appropriate amount of cursing HDMI and modern electronics is general, until my daughter reminded me that I design modern electronics. Moving on, I tried the unplug, factory reset, etc, eventually I decided this is probably really broken. It's 7 years old, it's been worked pretty hard in our family of 5 ... but it's a beautiful TV, and I'm not ready to scrap it.
Due to marital factors, I'd very much like to take this thing off the wall, do my thing, and get it back up. If I can get to 90% certainty which part(s) needs replacing, I will pre-order, and hope to fix it within a day. Getting the TV off the wall means getting someone to help, and having it down means an ugly recessed area with cables etc right in the living room. First world problems, I know. I realize this plan has a significant chance of failing, but one can dream.
I have the service manual (from another thread here). I believe the problem is a bad main (A) board. The following are my data points:
1. It shows the "studio master" splash screen perfectly
2. No blinking red light
3. It doesn't show any menu's (or anything), but responds to remote pushes with the sounds I expect from navigating menus
4. ONCE, after leaving unplugged for a day, it worked fine until it was next shut off.
The above lead me to believe it can't be panel, buffers, etc (cuz I get splash screen). It can't be tuner, HDMI, etc, because even menus don't come up. It's not a "hard fail" because once it did come back. It doesn't FEEL like a bad cable anywhere but I'm less confident about that.
I'm guessing bad solder joint, or bad cap, on the main (A) board.
If folks agree with that diagnosis, my plan would be to order the part in advance. When the TV is down, giving it a dusting, alcohol cleaning the connectors. I'd rather avoid swapping a board if a cleaning is all she needs. But if that doesn't fix it, and I don't think it will, replace the main board. If THAT doesn't fix it, update my will, consider skipping town, look for bad caps to see if there's anything else I can replace (I have a decent spare parts pile), measure whatever voltages I can find for clues, take pictures, etc.
My questions are:
A) am I right that it sounds like Main (A) board? (TXN/A1UVUUS)
B) what are some recommended places to find that in 2021? I've seen it on eBay (~$244) but it was out of stock at the couple of parts sites I tried
C) most of my diagnosis hinges on the assumption that the splash screen is driven from the Main board, and isn't embedded in some other board or the panel itself, is that a good assumption?
D) if my symptoms ring any bells, would love to hear your story
To be real specific, my theory is that the splash screen is coming from one of the chips downstream from the main PEAKS-PRO4 chip (two downstream chips have Flash). The audio comes direct from that PEAKS-PRO4, but video goes through a "GCX" chip (with Flash and DDR3) sitting between PEAKS-PRO4 and another Flash-equipped "PD6H" chip that drives most of the video cables to the sub-boards. So looking at block diagram and my symptoms, I'm thinking it maybe a GCX chip failure (if PD6H drives splash screen) .. or .. link between PEAKS and GCX (if GCX drives splash screen) ... or something else interacting weirdly; hard to say. But looking at the block diagram, it seems pretty sure that the issue must be in the Main (A) board, right??
I have attached the service docs I found in other threads, for anyone that wants to look, or future like minded folks who stumble on this thread.
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