For background I am an electrical engineer with a full time design job and a hobby repairing MacBook logic boards. I know my way around schematics and have a decent microscope and soldering setup.
I had a lightning strike near my home which has knocked out the 3 HDMI ports on my 2.5 year old Panasonic TC-P50U2 set. My Mac Mini that was connected to the TV through HDMI is fine. This is actually the second time this has happened but the first time was during warranty period and they changed the main board. The first time it also took out the HDMI ports on my Harmon Kardon receiver so I just stopped using the receiver for switching HDMI signals. I don't know why the HDMI ports are so sensitive. All of the pther ports and functions are fine. I had a look at the schematics in the service manual and I see a couple of TVS diodes on the I2C data and clock but those are really for ESD not lightning. Maybe the grounding on the HDMI ports is not references solidly to the TV chassis ground...
I measured the 3 HDMI ports and the only odd thing I could see waas that the impedance to ground on the I2C signals was OK on ports 2 and 3. I think 4.7K and 47K going from memory. But HDMI port 1 was something like 40 ohms to ground. Unfortunately these signals go straight to the signal processor chip which is a BGA that I am not about to change. Likely the DSP chip itself is fried. Not exactly sure why the fault on HDMI port 1 also affects ports 2 and 3 given they seem to have different I2C busses.
Anyway, that is the background. Now I am on the hunt to replace the main board TNPH0831 with suffix code AJ. Can't find them anywhere in stock. A couple of old eBay listings but nothing current. I have found a few of these with different suffix codes from different model TV's that appear to have the exact same components and IO connections.
So here is the question. The suffix code seems to be controlled by the bank of 5 resistors. If I got a board with a different suffix code could I "change" it into my suffix code by adjusting the resistor network to match? Or is there firmware on the board that would also need to match up to the suffix code.
Any help appreciated.
I had a lightning strike near my home which has knocked out the 3 HDMI ports on my 2.5 year old Panasonic TC-P50U2 set. My Mac Mini that was connected to the TV through HDMI is fine. This is actually the second time this has happened but the first time was during warranty period and they changed the main board. The first time it also took out the HDMI ports on my Harmon Kardon receiver so I just stopped using the receiver for switching HDMI signals. I don't know why the HDMI ports are so sensitive. All of the pther ports and functions are fine. I had a look at the schematics in the service manual and I see a couple of TVS diodes on the I2C data and clock but those are really for ESD not lightning. Maybe the grounding on the HDMI ports is not references solidly to the TV chassis ground...
I measured the 3 HDMI ports and the only odd thing I could see waas that the impedance to ground on the I2C signals was OK on ports 2 and 3. I think 4.7K and 47K going from memory. But HDMI port 1 was something like 40 ohms to ground. Unfortunately these signals go straight to the signal processor chip which is a BGA that I am not about to change. Likely the DSP chip itself is fried. Not exactly sure why the fault on HDMI port 1 also affects ports 2 and 3 given they seem to have different I2C busses.
Anyway, that is the background. Now I am on the hunt to replace the main board TNPH0831 with suffix code AJ. Can't find them anywhere in stock. A couple of old eBay listings but nothing current. I have found a few of these with different suffix codes from different model TV's that appear to have the exact same components and IO connections.
So here is the question. The suffix code seems to be controlled by the bank of 5 resistors. If I got a board with a different suffix code could I "change" it into my suffix code by adjusting the resistor network to match? Or is there firmware on the board that would also need to match up to the suffix code.
Any help appreciated.
These boards are hard to find for some reason. I was told Panasonic stopped making them. My TV is only 3 years old and can't get parts. Doesn't seem right.
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