Sony Trinitron Question??? - Videokarma.org TV - Video

mjennens · #1 06-10-2009, 06:19 PM

I'm trying to help a friend see if his TV is worth repairing. Here's his problem:
-The TV won't power on
-He can hear a click, but the only response is a red blinking "Stand By/Timer" light

The TV info is: model # KV-32S42, 32 inch Trinitron, manufacturer year 2000

He found a post on the Internet that said leave it unplugged for a day and see if that helps. It didn't.

I know that's a sketchy description of the problem, but have any of you TV folks heard of this and know what I could check for him?

Thanks,
Mike

radiotvnut · #2 06-10-2009, 06:32 PM

If you have what I think you have, you'll likely find a shorted horizontal output transistor, two shorted switching transistors in the power supply (these may actually be two transistors in the same package since this is a 2000 model), and an open low ohms fusible resistor in the power supply. It will probably be white in color and be located close to the heatsink that the shorted transistors will be attached to. The most likely reason for these parts failures is loose connections in the horizontal deflection circuit, especially the horizontal driver transformer. It's best just to resolder everything in the horizontal output and drive area. Unfortunately, other things, like a bad flyback, can also cause the parts to blow. The only way to check the flyback is with special test equipment. If you don't have access to such equipment, you'll have to take a chance with the parts and resoldering and hope it does the job. I had a 36" Sony from 2000 that smoked new parts despite my efforts to prevent that. I decided to junk the set rather than blow money on a flyback and the other new parts just to have the whole thing blow up in my face.

BTW, don't use cheap chinese knock off parts in this application. Many places sell a cheap parts kit for something like $9.99. I would not recommend going that route. It would be best to spend a little more on the original Sony parts. Many of those knock off parts will either instantly blow up or fail within a short period.

mjennens · #3 06-10-2009, 07:43 PM

RadioTVNut,
Thanks for the info. Do you happen to know the designators for the suspect parts, or part numbers? I'd like to get a price and see if my friend is willing to gamble on the flyback not being bad.
Mike

radiotvnut · #4 06-10-2009, 08:34 PM

I don't remember the numbers at the moment. The horizontal output transistor (HOT) will be a fairly large, black transistor w/ three terminals attached to a heatsink close to the flyback transformer. The flyback is the large device with the large red wire coming out of the top that connects to the top of the CRT via a suction cup.

The other transistors in the power supply will be on a heatsink on the smaller power supply board. Since your set is a 2000 model, I'm thinking that instead of two seperate transistors; there will be an IC with six terminals mounted on a heatsink. This IC is actually 2 transistors in one. The small white fusible resistor will be close to that heatsink on the power supply board.

I think I had around $30 in the parts that I had the displeasure of watching fry as soon as I hit the power button. The flyback would have been another $50 + $30 more dollars for new transistors, etc. I would have had over $100 in a set that might not have worked. And, I'm really not a fan of newer Sony's; so, making the decision to junk that TV was fairly easy.

Find out how the picture was before it went out. I've seen plenty of Sony's of this age with weak CRT's. The symptoms are poor color, color bleeding, poor focus, and a picture that flashes on and off. Sony's from this era have an AKB circuit to automatically adjust the bias for the CRT. When the CRT becomes too weak, the circuit can't compensate for the defective tube and the picture flashes. If you find out that the picture was poor before it went out, just go ahead and dump it.

radiotvnut · #5 06-10-2009, 08:46 PM

Oh, and I'd check the HOT with an ohmmeter to confirm that it's shorted. If it is, the other parts will be bad.

Findm-Keepm · #6 06-10-2009, 09:23 PM

Here's a schematic of the power supply board - the "G" board. Your set uses the MX0841 transistor pair - only the Sony-supplied devices will last. There is a bulletin that has you make some mods and replace some other parts - be sure to follow the instructions, or you'll eat the MX0841 again. Yes, the flyback could also be bad, or it could've been a surge or lightning strike set..

Save the file and zoom in to see the detail - viewing it in the web browser ain't gonna cut it. PM me if you need the full manual.

Anyway, hope this helps,