I have 27" Panasonic CRT from 2003 (uses an Orion tube) and at the base of one of the big resistors, the PCB is black. The PCB is also blackened around the nearby components. It isn't charred; it's just black in color. The rest of the PCB looks normal. The solder joints in this area looked pretty bad so I re-flowed them. I have the service manual for the TV and the resistor in question does measure at it's correct value of 27ohms. I also pulled out the transistors, diodes and other nearby resistors and tested with a multimeter and I got normal readings. I suspect there's some sort of over voltage problem but I don't know what's causing it because the parts in the blackened area of the board are testing fine. The picture on the TV looks normal. Looking at the service manual for my set, I can see that this resistor has something to do with regulating 5V current but I'm not sure where to go from there.
I made a post on the EEVblog forum where I included a photo of the board, the schematic for the resistor in question as well as the service manual. You can view the post here,
https://www.eevblog.com/forum/repair...ure-the-cause/
04-22-2025, 03:18 PM
Threaded Mode