On a "no signal" condition, the CRT has snow and the brightness is normal. When a signal is applied, either at the antenna terminals or at the A/V input jacks, the video is very dark with streaks and black splotches in the picture. I can turn up the sub brightness to make the picture brighter; but, it is still streaky with the black splotches. I have the sams photofact on this set and have already checked several caps and transistors and I'm getting tired of fooling with it. I just thought I'd ask someone on here if they'd ever seen a similar problem before I junk this one.

Sounds like the signal overloads it. I'd bet the problem is in the video amp. Is that where you checked?? Might be an AGC problem too....

Yep, the video circuit is where I checked. When I cranked up the sub brightness control and looked at the picture more closely, I noticed that the picture is not very sharp and there are black streaks, especially when writing is present.

I suddenly remembered an '80's 19" "PC" chassis GE doing that and it was a small value electrolytic in the 200V line to the video output stages. I've already checked the electrolytic in the 200V line in the Toshiba and it is good. I'm going to check the rest of the electrolytics in the power supply. Maybe I'll get lucky.

Well, I think I MIGHT have solved the video problem; but, the vertical circuit decided to take a dump before I could find out!

I found C126, a 100uf16V cap in the B+ line to the video stages to be reading only about 5 uf. I replaced that cap, turned it on, and I could smell a resistor heating up. A glance at the screen showed the raster to be shrunk and folded over. Then, the whole thing went to a horizontal line. The vertical IC (IC301 - AN5515) is bad along with the 220 uf pump up cap (C322) and the fusible resistor (R327 - 5.6 ohm). I'll replace these parts and maybe it will be fixed. If not, it's going to the curb.

Good luck Bryan! My Toshiba experience was less than desirable.....

Well, it's not looking good. I replaced the vertical IC, the 220uf cap in the pump up circuit, and the 5.6 ohm fusible resistor off the flyback. It still comes on folded over with a shrunk up raster and the fusible resistor gets red hot in a matter of seconds. The vertical IC remains cool. I checked all the other caps in the vertical circuit and found none bad. I did find another bad 100 uf cap in one of the low voltage supply lines coming off the flyback; but, changing it did not help the vertical problem. I also replaced the diode across the vertical IC with no luck. When I get back on it, I'm going to change the B+ diode coming off the flyback. If that does not solve the problem, the only other thing I can think of would be a bad yoke and we all know what's going to happen if that's the case (unless I can find a good used one).

Really, the only reason I'm spending this much time on this set is so that I can keep from adding it to the garbage pile, since it's getting harder and harder to dispose of a junk TV. At least if I get it working, I might be able to find a home for it. I just know it's getting harder and harder to move a used CRT TV for any decent money and it's really not worth spending hours, or days, troubleshooting a TV only to end up selling it for $20 after it's been sitting here for six months. I need to remember that the days of getting $150 for a TV like this have long passed and just stop taking them in.

Well, you can give me the STUPID award of the year. I discovered that I installed the filter cap for the vertical B+ backwards! Turned it around and the vertical was normal. I can't believe I did that! Once I got the vertical back to normal, my video problem is still present. I have replaced several confirmed BAD 100 uf caps in the low voltage B+ lines leading to the signal circuits and still the same thing. Here are some pictures of what it looks like. The first picture was taken using the DTV box menu with the color control on the TV turned down. Second picture is a B&W image of a program. The third picture is of the DTV box menu in color. Disregard the shading at the top of the screen as I need to degause the CRT. The signal source is a Channel Master DTV box connected via the A/V input jacks. Any last thoughts before I lower the boom on this set?

http://i538.photobucket.com/albums/ff341/radiotvnut/2009_0915toshiba0004.jpg

http://i538.photobucket.com/albums/ff341/radiotvnut/2009_0915toshiba0003.jpg

http://i538.photobucket.com/albums/ff341/radiotvnut/2009_0915toshiba0002.jpg

Progress is progress no matter how small a difference. We've all put a cap in backwards at some point. No worries, at least it didn't wreck it.:)

Changed more bad caps, mostly Marcon branded 10 and 100 uf, and still no change. Still the same smeary picture. I wonder why they even bothered to put these caps in the circuit if their condition is not going to make any difference in performance. I'm going to play with it a little more tomorrow. If things don't change...I'm done with it.

I hate it when one gets the best of me and never gets fixed, even when I want to throw it away, I can't leave it alone until I figure it out. Even though the guy threw out the rest of the one I was working on, I'm still messing with the chassis trying to revive it:)

I replaced more bad caps and it now plays pretty good for the first five minutes or so. Then, the picture gets washed out and a little smeared. It's still watchable and that's all I'm doing to it. It's obvious that this set had a bad run of caps and I don't think it would be practical to change every electrolytic in the set. I think it would be best just to let this one go cheap and let the buyer know why they are getting it cheap. Heck, I may just drop it off at the SA and be done with it.

Progress is progress no matter how small a difference. We've all put a cap in backwards at some point. No worries, at least it didn't wreck it.:)

I'm surprised that, if it was installed backwards, that cap didn't explode as soon as the B+ came up to normal. Electrolytics do not take kindly to being installed in reverse. I've never seen one explode, but I have read horror stories here and elsewhere telling of electrolytic filter caps, installed backwards, that have gone off like a bomb several seconds to a minute after the TV, radio, etc. was powered on. The shrapnel thrown off from an exploding electrolytic cap can cause serious injury as well but, as the OP noted, the cap involved still worked (and the TV picture returned to normal) once the part was installed properly, so it seems as if it all worked out well in the end. :yes: