Sony KV-2784R horiz problem

Hi!

In light of that, are you sure that the low power/standby power supply is working properly? Perhaps it sustained some damage during the failure, or a protection circuit opened up?

William

I've found that usually when a fuse is blackenend the problem is generally close to the fuse like one of the bridge diodes. I'm assuming you replaced the fuse and the ne one blew the same way? Look for something dead shorted. Lenny

If you post your e-mail address, I can help you with the schematic.

Thx for the replies..

I pulled the chassis to bring it home - the set is at my other house and I did not have any tools there.

Therefore I have not replaced the fuse yet as I have nothing to connect it to.

I was thingking about a low voltage issue because of the remote not working, I just don't know where that fuse is in the ckt and something is getting volts as it tries to start. Since it was near the horiz section I made an assumption. could be wrong. Don't know if the whistle I hear is the horiz freq or the switching supply.

tipsnews at nc.rr.com

thanks David.

I was thinking that is was the AC line fuse that was blackened. however from what you said it doesn't sound like it. I don't know what other fuse you could be referring to other than a small chemical fuse on a 27 inch set though. Lenny.

the AC comes in on the right, passes thru some rectifiers and large caps etc. There is a small metal box on the left which I believe has a switching PS in it - haven't opened it yet. The fuse is about in the middle on the back edge - a mini fuse - just about where the horiz section starts - the HOT is on the left side near the box. I don't see another fuse and none near the ac line.

Most common failure on these is a shorted flyback. Chuck

Thanks Chuck, I was just going to ask that.

How is it usually checked.

There is no continuity between coils at DC. coil resistance seems within reason but as low as it is that probably isn't a very good test. I haven't got one laying around to sub. It is, after all, 24 yrs old. But the CRT is still OK.

Can they be had and at what price????????

If you have a scope with a ten times probe, set the V. input for the highest voltage possible and the H. rate at 20 us and connect the probe to the HOT collector after plugging the tv into an isolation transformer. Replace the blown fuse and turn on set. If there is ringing between the HO pulses, power the set down immediately and order a flyback replacement. I'd check MCM for a replacement. If they don't have them, sometimes an Asti flyback will work in a Sony set. (I haven't had any luck with them for other brands.) Chuck

OK, I am operating on probabilities here. The rest of the set is 300 miles away. I have a scope and other necessaries but can't plug the tv in. My extension cords are not long enough. I can get a new fbt for about $15. what is the probability that will fix it when I carry the chassis back and fire it up????????????

I have checked all semis with an ohmmeter and find nothing unusual. The set is 24 yrs old and neer had a problem. Caps all respond properly to an ohmmeter. I could pull some parts and ring them with ac but....

What is the probability a fbt will fix it??

thx

Shut downs are a pain in the ass. I've done some of those 300 mile deals as well and they aren't much fun either. So you have no CRT or yoke and no jig I take it. Pull the flyback and take it to a shop that has a ringer. Perhaps for a couple of bucks you may be able to get a sympathetic tech to ring it out for you. At least that way you won't have to hold your breath ( too much) on the return trip. Lenny

If anybody is still listening - THANKS for all your help

I finally got the flyback and put everything back and it works perfectly.

No there parts needed, 'cept the fuse.

You are welcome. Chuck