Advice needed on Sony KV-32S45 repair

[3Guncolor]

Advice needed on a 1998 Sony KV-32S45

I have a 32” Sony KV-32S45 that I’m having trouble with. Three weeks ago the set just stopped running with the standby light blinking. There were no signs of the main power supply running. After the looking into the problem I found the main driver transistors in the B+ switching power supply were shorted and the fusible resistor was blown. I also found the horizontal output transistor shorted. I checked all caps on the “G” “power supply” board and everything checked out. I also checked the damper diodes and other components in the horizontal circuits. Nothing else wrong was found

After the shorted transistors and resistor were replaced I soft started the set on about 40 volts AC. The set powered up and worked correctly. I went to full power and all was still normal. The set was put back into service.

After about a week of use the same thing happened, the set just stopped running. I found the same parts blown and so far no signs of other failed parts. I don’t really want to give up on this set but I know if I just replace these parts again and the set powers up it will only be a matter of time before the same thing happens again. Before I invest another $60 into the set I was hoping somebody may have an idea was may be causing this. The set worked correctly until it quit again no signs of any malfunction.

My thoughts are that the horizontal area may the cause of this problem. Would it be worth replacing the flyback? I think the power supply is only failing because of the load from the shorted horizontal output. I have the service manual for the set and have access to every piece of test equipment needed for servicing it. I’m hoping somebody who works on these sets every day has learned what may be causing this and can save me the expense of just hoping it will stay running each time I get it running again.

Steve

[andy]

Resolder the horizontal driver transformer (off the base of the HOT). This is a common problem with 90's Sonys. When the horizontal drive drops out because of the cracked soldering the HOT shorts and takes thw power supply out.

[3Guncolor]

Andy,
I took a look at the solder on the drive transformer and found it was cracked. I should have known better, on this set I had to resolder the vertical output a few years ago due to the same problem. I'm going to order the parts one more time and see what happens. I'm also going to check all the connections on the horizontal area. I was thinking it could have been a drive problem but I couldn't find anything wrong. I'm getting older and my eyes are not as good as they used to be. After I looked at it through an eye peice it was easy to see. Thanks for your input you might save me from having to buy a new LCD set my family is bugging me about. We wanted to use this set until the new sets get better and maybe cost less.
Steve