WS-55511 strange convergence problem, processor won't boot.

[jtaylor]

My father-in-law's Mitsubishi WS-55511 TV all-of-a-sudden started showing all three colors offset from each other. Photo below. When the TV was cold, I could hit the convergence reset and everything would re-align. After the TV warmed up, if I changed inputs, the convergence would go to the way they are shown in the attached photo. I had an extra convergence IC, so I checked the fuses and replaced it, not thinking that was really the issue. Solder joints looked good on the old convergence IC, but replaced it anyhow.

After powering the TV back up, the processor won't boot and all I get is the blinking green light. This seems odd since the TV was powering up just a few hours ago. I pulled the DM module out and am planning to replace the caps in it. There are 7 1000uF, 16V caps in the DM module. They look fine, but my understanding is that looks can be deceiving. All the caps in the DM are Jamicon. The TV was produced in October 2003.

1) Are the 7 1000uF caps the right ones to try? Are there others I should replace while I'm at it?

2) What do you suspect the issue was initially? Does this look and feel like the convergence IC?

Maybe there were two problems before I started working on this. The TV hadn't been rebooted since before the convergence issue.

Thanks for any help you can lend. Trying to figure out if I'm going in the right direction.

Photo below.

jt

[lcaillo]

Not sure about the convergence problem...more info would be needed.

Yes, the 7 caps in the DM are the ones to change. The problem was there, you just did not notice it until the unit needed to re-boot.

[jtaylor]

Thanks for your help. I ordered replacement caps from ACME. I ordered 25v parts rather than the orignal 16v parts after I verified there was enough room. Same diameter. TV booted up just fine and is working. I do see some new noise though. When I have the convergence tuning grid up on the display, the upper 25% of the display is a little bit wavy. Not hugely, but a little bit. Bottom 75% looks very smooth. The waviness changes as if there is some new noise or coupled interference now. Is it possible I bundled the wiring back together poorly and there is some cross talk between cables?

I suspect the original problem to be an issue with the processor accessing the convergence calibration values. Worked ok when the TV was cold, failed when warm. The caps I took out measured from about 710 uF to 950 uF. The new ones I put in measured between 990 and 1000 uF.

Regards,

jt

[lcaillo]

You might check the power supply caps in the secondary supplies. ESR testing is usually a good way to identify bad ones.