** Who does TV repair?? **

[omslaw]

If anyone does TV Repair, I sure could use some advice...

My Mitsubishi WT-42311 shot craps on me. Flashes a Code 22 (Short Protect Circuit).

I've got the service manual and have been looking at the power supply and convergence circuits.

I've read that there have been problems with the convergence ICs going bad. I suspect that there may be a diode or transistor or fuse bad, too.

I was just wondering if anyone had worked on one of these chassis (VK-20) before and could give me some advice on where to look.

Thanks!

 

[fsusux]

It's been a while since I worked on tv's and never on that chassis but I would suspect the convergence STK's. also check for any blown pico fuses in the power circuits going to the ic's. Your main power supply is probably ok. Look for good 5,12,-12,24 & -24 volts coming out. Some sets also use 9volt regulators as well.

Back when I was still doing tv repair I had a subscription to Repair World I can't tell you how many times doing a search there saved me from a real dog repair. It costs a few bucks for a month's subscription, but it may save you from a hefty repair bill.

Good luck!

~Jason~

 

[omslaw]

Woo Hoo!

Fixed it!

Cold solder joint on anode of +24v diode in PS board.


Thanks for the help, Jason!


--Omar

 

[fsusux]

Ahhhhh. Bad connections, The bane of my existence! What led you there?

 

[omslaw]

I pulled the 'chassis' out and re-checked all the pico fuses...all were good.  I was getting ready to check for all the proper voltages when I recalled a post I found on repairworld (thanks for pointing me in that direction, BTW) that said to check the fuse on the +24v line - it's been known to open.  I was gonna pull it outta the circuit to double-check it.  I was visually checking the solder connections on the fuse, when I caught something outta the corner of my eye.  I had to re-focus to find it, but I saw what looked to be like a cold joint.

I grabbed a flashlight and my probe and 'wiggled' the lead and whaddya know, it (and the solder) moved back-and-forth!  I flowed some more solder on the joint and then decided to try it...VIOLA!  It worked!  I had the convergence STK's, I went ahead and replaced them and re-converged.  All it working well!  Watching it now as I write this!  

Basically, it was a lucky find

 I had looked over the PCBs a couple times before and didn't find anything.  Though, I'm sure I would have found it when I started probing for voltages....just saved me all the trouble.   (It sux that I dragged all my test gear upstairs for nothing...but oh well.)

 

[heavybusa]

Nice work!!

 

[fsusux]

Awesome! Repair world saved me countless hours of troubleshooting back in the day. Even if it didn't show me the exact problem i was having, it often pointed me in a direction i hadn't previously thought of.

Glad you got fixed on the cheap bro!

 

[omslaw]

(heavybusa @ Jan. 16 2007,21:51) Nice work!!

Thanks, HB!

 

[omslaw]

(fsusux @ Jan. 17 2007,08:08) Awesome! Repair world saved me countless hours of troubleshooting back in the day. Even if it didn't show me the exact problem i was having, it often pointed me in a direction i hadn't previously thought of.

Glad you got fixed on the cheap bro!

Thanks! Yeah, I'm glad I was able to fix it, too! I was dreading what could have been several hundred $$ repair bill! I'm gonna definitely bookmark that site; came in handy!

(OTOH - when I told my wife how much it could cost to fix if we had to have a tech out, she started looking at plasma/LCD sets. I think I should have said it was broke

)