Hey all,

I've got one of these things in my kitchen...I think I picked it up about...a year ago....maybe two...but..I haven't had it very long.

anyway, sitting around this morning, watching TV, drinking coffee...and the thing cuts off...it didn't just power down, it hardcore just...went out.

I know it could be a number of things...does anyone have any experience with this piece of crap (i call it a piece of crap because with the fact that *anything* i've owned with the RCA moniker...well, has been a piece of crap...but also breaks within a year)...maybe a service manual, troubleshooting guide i could maybe follow? I don't wanna blindly jump in to trying to fix the thing.

And before you ask...yes, i'm fully aware of the dangers of the flyback and high voltages inside the thing....I do work on CGA video monitors for acrade games...

I don't know about the smaller screen sets; but, the newer larger screen RCA's are prone to eat flybacks. If this set were mine, I'd check the fuse, diodes, and regulator. If those are good, I'd probably let it go. If the HOT is shorted, the flyback will surely be bad. You could also have a shorted vertical IC. Best way to tell would be to remove it and see if the set comes on.

Thanks for the advice.

That's pretty much what I do to video monitors when I don't know WHY they're not working.

All the diodes I checked seemed ok except for one, but I haven't ruled out there being something across the circuit.

The HOT appeared to have an emitter/collector short...when looking at the datasheet for the thing it has an internal diode across the collector emitter. The emitter runs right to ground...and there are tiny caps from the collector line to ground...i believe that is why it's testing shorted with my meter, I have yet to remove the thing from circuit.

I do have a question. I'm used to working on open-frame CGA monitors...so when I want to discharge the flyback, I generally just clip-lead a flathead screwdriver to the chasis, run it under the insulator and call it done. There's a ground strap going around the tube which runs to the neck board...I'm thinking I can discharge it there...but I'm not sure. never really touched TV's.

The thing doesn't even go in to standby mode...so I'm looking at the schematic in an attempt to figure out if a shorted HOT and bad flyback would cause that or if there's another problem at hand...just gathering ideas in case it's not a blown HOT and FB.

Yes, you can discharge the CRT to the ground strap.

If there's a short on any of the B+ lines coming off the secondary of the power supply, the power supply will shut down. I'd pull the HOT from the circuit and re-check it. If it's bad, assume the flyback is gone, too. That's not an across the board rule for all TV's; but, it generally is for newer RCA's. If the flyback is bad, you can probably get one cheap; but, it will probably crap out again in a year or two. I just tossed a big 32" RCA SDTV (ATC010 chassis) with a bad flyback and HOT because I knew that even if I fixed it, the chances of it holding up were slim.

Well, I just came across this exact POS as part of a bunch of TV's that were turned down for repair at a local TV shop. And, it really is Chinese junk full of no name Chinese caps. When you turn it on, a bright spot flashes in the center of the screen and the B+ runs around 72 volts. If I leave it on for about 30 seconds, the B+ will gradually rise to 106 volts and a picture appears (although not a very good one, looks like a weak CRT or an improper greyscale setup). I replaced both caps (100uf, and 47uf @ 160V) in the B+ line; but, no change. I checked some more caps; but, they seem to be OK. Given that it's nothing special, I'm about to send it to the TV graveyard if I can't come up with something pretty quick.

Hmmm, why would a bright spot flash on the screen if the heaters are not even warm yet. Wonder if something physically arced in the CRT?

It does take about 15 seconds (time for the tube to warm up) before it starts flashing. I didn't make that clear earlier. Next, I think I'll check the rest of the power supply voltages to see if the rest are low or if it's just the high B+ line that's low. If I can't find anything there, I'll disconnect the B+ from the flyback to make sure something in the horizontal sweep circuit is not causing the problem. If I still find myself up a creek, this TV is going to wind up on the junk pile.

It's looking like the flyback may be the culprit. I can disconnect the B+ going to the flyback and the 105 volts comes up as soon as I press the power button. When I reconnect the flyback, the B+ starts out in the 70 volt range while the screen flashes in the center and then it runs on up to 105 volts and works. So, it's either the flyback or something off of the flyback. I've seen a lot of these newer Chinese RCA's with a bad flyback; but, they were always totally non functional. I've never seen one that would act up for a minute and then work.

I've seen the scan derived (flyback secondary) supplies get loaded down and cause low B+. Around here, lightning takes out the tuner, shorting the tuner B+ line off the flyback and loading things down. You can lift / isolate the tuner B+ pin and check to see if it lights off. If so, Bingo, bad tuner.

Two years ago, MAT Electronics sold entire TTE M134 chassis for $19.95. They were great for getting the B+ fuses and PS diodes off of, and we even used an EEPROM off of one once. They still have some RCA chassis left, I think. No relation, just a customer. We also got our Hakko stuff from them - better prices.

Cheers,

I did disconnect all of the secondary sources from the flyback and it does the same thing - starts at around 74 volts and then creeps up to 105 volts. When I removed the B+ input to the flyback, the 105 volts came up instantly.