27" CRT TV blackened area on PCB near big resistor, not sure the cause?

[CRTguy]

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/

[old_tv_nut]

It seems obvious that the resistor was replaced at some time, so the blackening came from the original resistor, which would have been mounted close to the board. If everything checks OK, it is OK.

[vol.2]

I've had many TVs, especially from the late 80s and early 90s have power areas go black from heat just from heavy use. Nothing has to be critically wrong with the set, but it may indicate a high hour tube.

[CRTguy]

Originally Posted by vol.2

I've had many TVs, especially from the late 80s and early 90s have power areas go black from heat just from heavy use. Nothing has to be critically wrong with the set, but it may indicate a high hour tube.

I will just continue using the set. It's not super high hour (has 11,450 hours on it as confirmed by the service menu). I may replace that 27ohm/3W resistor with a 27ohm/5W resistor for added safety. At some point, though, I may want to measure the voltage going across that resistor while the set is running.

[CRTguy]

UPDATE:

I was working on the board and the leg of that big resistor (R629) was touching Q608 and when I powered on the TV, it fried Q608. Now the TV powers on for 1-2 seconds and I can hear it running but then it powers off. When the TV powers on, the screen does not appear to turn on. With Q608 having failed, does it make sense that the TV would show these symptoms? Could any other components have been taken out when Q608 failed? I'm concerned that the Micon IC, Vertical output IC and horizontal drive transistor may have been damaged. I can easily order a replacement for Q608 but hopefully it's not any worse than that.