TV repair

[OldHouseScott]

The internet can be a wonderful thing. About a year and a half ago, my 20+ yo Mitsubishi TV started acting up with foldover at the top of the screen which would go away after about 5 minutes. Finally it shrank to a thin horizontal line across the middle of the screen. Still had sound though. I thought it was a goner and would cost more to repair than it was worth so I stuck it in the garage and went out and bought a new Sony HDTV flatscreen. With HD content it looks gorgeous. With SD content, not so much. The old CRT looked better with the SD stuff. Anyway, right after Christmas, my slightly more than 1 yo Sony decides to go on the blink. Good thing I bought the extended warranty. While waiting for the Sony to be repaired, I decided to do a little surfing about the old Mitsu and found several archived forums with problems similar to mine. Turns out it's a fairly common problem with those (and many other) Mitsu sets and can be repaired with about $10 in parts. A few eBay purchases later and some soldering, and voila! the old Mitsu is back in business. I also got the replacement for the (non-repairable) Sony at the same time, so that goes back in the TV cabinet, but it's nice to know I've now got a functional backup should the new Sony go the way of its predecessor.

I would never have attempted this repair before being inspired by this and a few other forums in building and troubleshooting amps over the last several years.

[EL34]

Wow, that's cool.
I usually think of TV's as "not worth repairing"

I gave my big screen CRT tv to my neighbor (still was worthing great) and he was a happy guy
He had some little tiny crt tv.

I grabbed a sweet deal on a monster plasma a couple years ago.

Anywho, a buddy of mine's Mitsubishi took a dump.
I'll have to find out if it was doing the same thing as yours

Thanks for the info

[Bassmanster]

My dad did TV repair in the 50s.  As I got older, it took longer and longer for him to effect repairs.  I remember he and our neighbor spending hours looking for the bad transistor on a discrete color TV.  In the 80s he gave up.

[RicharD]

CRT's are dangerous to work on.  Way more potential than a tube amp.  Just sayin......

I had a filament die on my CRT.  Some old timer on the web talked me through adding my own filament winding.  30" of wire, 2 solder joints, and 1 dremel cut later and my TV was working again, to which my wife said, "We're never gonna get a flat screen TV are we?"

[OldHouseScott]

Yes, I was careful to give the picture tube and all the HV stuff a very wide berth. Fortunately, most of the electronics were on a slide out tray in the bottom. If it had been more than a chip and a few resistors and capacitors, I would have passed.

[PRR]

> shrank to a thin horizontal line across the middle of the screen. Still had sound though.

Still has everything except Vertical Sweep. Turn down the BRITE, you can see that line's brightness change from scene to scene-- the image is there, just all 300 lines jammed into one. If you hold an AC electromagnet near the neck, they will spread-out to a badly distorted and rolly but recognizable image.

Look for sagged-to-nothing B+ to V-Sweep stage. Replace the V-sweep tube. Replace timing resistors and caps in V-Sweep stage. Buzz the V-Sweep OT, they are not so hard to replace.

Ah, non-tube? Dried-out V output electrolytic. Then.... yeah, it takes too long unless you find someone else's notes you can crib. Glad you found some.

[OldHouseScott]

You nailed it, PRR. Dried out electro in the V-output circuit. Eventually the V-output chip overheats and dies.

[billcreller]

I just tossed an old Mitsi TV because it was folded over.  It was a bedroom TV. Bought my wife a flat screen type. She likes it, I don't.
Our main TV is also a Mitsubishi, 26".  I've had it fixed twice, and will again, rather than buy another flat screen.  I don't need a big screen to watch trash TV which most of it is.

[rafe]

Just to touch on what OHScott said "The internet can be a wonderful thing."
I'd be lost without having access, right in my diggs, to every question on any subject at any time that pops into my cranium, It is an incredible tool. Not to mention, as I mention, That I have been watching awesome documentaries lately, from history to physics.Old shows too A-Z, Alfred Hitchcock to Zorro ....it is endless.
 

[bnwitt]

Yes the internet is amazing.  Like the fact that MIT has now gone open source and is sharing their class lectures for free to anyone who logs on.  Isn't it interesting though, that today's americans are for the most part completely uninformed and poorly educated.  Even those at the top of the heap ain't to sharp.  If you want to see the difference in knowledge between today's americans and early americans read the Federalist papers written by Alexander Hamilton, James Madison and John Jay.  Good lord those early founders were brilliant and they didn't have the internet, electric lighting or even Barnes and noble.

[billcreller]

When my friends tell me about some one we know doing something stupid, I just say "he's average", meaning that the average US citizen isn't too swift.