SONY KV-2647R No HV

[ThePlague]

Hello All

I’ve been using this Sony KV-2657R 30P Chassis for about 3 – 4 hours a day for the last couple months. It appears to have been a low hour set with a very strong image.

Initially, the set would turn on it with a high pitch whine that would go away in about 20 seconds. Then recently it started doing the 20 second whine followed by a whine about 10 minutes after power on that would last around a minute. No picture degradation that I could detect, just noise.

A few days ago, there was a loud pop but the set kept running and the picture was fine. Sounded like a capacitor blowing. I powered it off and inspected it for any obvious signs of damage but found nothing. I used the set for another day and there was again a loud pop and I lost HV.

I inspected the unit again, but found no obvious signs of failed components. I suspected that the HOT may have gone bad. Pulled the HOT and performed a diode check and it came back fine. I replaced it with a NOS HOT I had just in case. I then noticed that the 125V 1.6amp fuse had blown. I replaced the fuse and powered on the set. That is when smoke came from resistor R539 near the flyback and there were high voltages arcing coming from the H-STAT on the CRT itself. I powered down the unit and pulled R539 and also C532 as it had a direct connection to R539 on one side and ground on the other. C532 came back fine, no short and capacitance value within spec. I also inspected capacitors C530 and C566 before the HOT as they had ties to ground but they were fine.

I powered on the set again and received a flash from the neon lamp NL601 for high voltage protection, the 125V 1.6amp fuse did not blow. There is no HV voltage present. I am a bit stumped as to why R539 would be the one to burn up, but I am now suspecting that its possible the flyback went bad, which would partially explain the whining sounds for the past couple months. The flyback is captured in the circuit as T502.

I just wanted to check with everyone if they have had a similar failure and if my flyback conclusion is justified. Thankfully I can source NOS flybacks for this unit for about ~$20. Hopefully there was no permanent damage to the H-STAT.