Multiple TV's, multiple issues

[ikeray]

I have 2 TV's that have 2 different problems.

firstly, an Admiral set 32" (or 36"?) who's picture is jumping/shaking up and down constantly. when it gets warm, it settles down some and we can tolerate it, but any text on the screen is unreadable (like sports scores). I've fiddled with the 5 knobs on the inside, Vpos Vmax, Hsize (or similar) and sharpness and white balance/contrast. someone said the horizontal or vertical (can't remember) sync is going out, I'd rather do the repair myself as I can't afford $100+ for someone to repair it or even look at it and I definitely can't afford a new TV.

secondly, its a sanyo 27" TV and the picture has collapsed into a single green line across the middle of the screen. how do I know thats the normal picture, it changes brightness and you can see tiny black dots moving about.



thats what it looks like.


when I had both TV's apart, I didn't see any bulging caps, but after looking at the images from the portal website (badcaps.net) I realized I was looking for caps that had exploded through the top, not just slightly bulged or goopy out the bottom

do you think I can tackle this task alone (my own labor...you're guys' help)?

[stj]

Re: Multiple TV's, multiple issues

1st tv, replace the caps around the vertical deflection chip,

2nd tv - do the same and if it's still screwed replace the chip.

resolder the chip and any other crap joints on both.

it's very common, the caps dry up - then blows the chip.
or the soldering cracks - then blows the chip.

btw, the vertical deflection chip is going to be bolted to a heatsink and probably starts with "TDA"

[Wizard]

Re: Multiple TV's, multiple issues

Or LAxxxx

First, can be bad solder joints in deflection circuits, especially of this vintage, best to take out power resistors and scrape them clean and reinstall with new solder and make sure to inspect real CLOSE for any bad or fractured solder. Also This can also be same problem as second TV (bad solder or noisy vertical IC).

ANd DO NOT leave that condition for another second!! This WILL burn a line across the face of CRT!!

Both have same problems.

Cheers, Wizard

[ikeray]

Re: Multiple TV's, multiple issues

Or LAxxxx

First, can be bad solder joints in deflection circuits, especially of this vintage, best to take out power resistors and scrape them clean and reinstall with new solder and make sure to inspect real CLOSE for any bad or fractured solder. Also This can also be same problem as second TV (bad solder or noisy vertical IC).

ANd DO NOT leave that condition for another second!! This WILL burn a line across the face of CRT!!

Both have same problems.

Cheers, Wizard

never leave the 27" tv on. after it was a green line, I shut the TV off, unplugged it and its been sitting for a couple of months. the admiral has been like this since we got it. we were told it went away after warm but it hasn't.

I was reading on eHow about them changing out caps (I don't trust the advice 100% like to get broader/more info from forums) and it said something about discharging the CRT prior to working on the board...how do I go about that?

if it ends up being nothing but bad solder joints, that'd be so much easier than having to replace the caps (well cheaper at least), I'll inspect the caps when I pull the sets apart but I guess it wouldn't hurt to try resoldering the joints first...

I'll snap some pictures when I pull them apart.

[stj]

Re: Multiple TV's, multiple issues

caps in tv's are junk, you can replace them with good ones.
but they dont need to be fantastic or expensive like in psu's & motherboards.

as long as it's rated at 105' for temperature it will do better than the original.

[Wizard]

Re: Multiple TV's, multiple issues

Yes, not too critical. Usually these are general purpose in most of circuits except for critical circuits where filtering is important especially flyback outputs and one cap for filtering B+ before the flyback's B+ input due to high freq (15.7Khz or 32KHz plus if it is a HDTV CRT chassis).

This is true for linear regulated hot chassis. On TVs with SMPS, better use good caps but not that toward extreme like mainboard caps. Rest of circuits only need basic decent caps (signal stuff).

Cheers, Wizard

[Krankshaft]

Re: Multiple TV's, multiple issues

I've seen TVs with a hybrid PSU too the 130V flyback B+ was done by a 130V regulator (on a live heatsink) and the rest of the low voltage circuits were done by a switcher in a Panasonic TV/VCR. Guess they saved money on a smaller switching transformer.

If you're TV is real old (like 1980s old) you may even find a linear standby transformer and the flyback will supply all the voltages with the set on.

When it comes to GP caps I use Chemicon KMGs they're general purpose 105 C caps they can be purchased from Newark Electronics.

For the switcher side I'd use Panasonic FCs they're low ESR and can be found at Newark although their stock is more limited than Digikey.

[ikeray]

Re: Multiple TV's, multiple issues

I've seen TVs with a hybrid PSU too the 130V flyback B+ was done by a 130V regulator (on a live heatsink) and the rest of the low voltage circuits were done by a switcher in a Panasonic TV/VCR. Guess they saved money on a smaller switching transformer.

If you're TV is real old (like 1980s old) you may even find a linear standby transformer and the flyback will supply all the voltages with the set on.

When it comes to GP caps I use Chemicon KMGs they're general purpose 105 C caps they can be purchased from Newark Electronics.

For the switcher side I'd use Panasonic FCs they're low ESR and can be found at Newark although their stock is more limited than Digikey.

probably my fault for not mentioning build dates...

the Sanyo is later '90's I believe, I can't remember the exact year, but I want to say it was '97. the admiral was either 2000 or 2001 (can't remember if it was 01/2000 or 09/2001).

I haven't had the chance to take either apart yet, a couple of other projects are slightly ahead of these in the "honey-do list".

[stj]

Re: Multiple TV's, multiple issues

most tv's you can work on without disconnecting the anode cable,
just slide the chassis out and turn it on it's side.

be ready to get dirty - make sure there is no female present to complain about how much dust is in the back!

[ikeray]

Re: Multiple TV's, multiple issues

well, I got the Admiral apart today and found out it is actually an Orion rebranded to Admiral - way to go Montgomery Ward or whomever...

anyways, I can't see any bad caps, or nothing that jumps out at me, and all the caps in the TV were Rubyconn's. there was one questionable, there was white goop on the board near the cap similar to the white goop/glue that is used to hold the wires down to the board, the only issue was there wasn't a wire near the white goop and the cap was bent away from it (bottom pointed towards goop).

do caps go bad w/o visual evidence? if so, what else could it be? if not, would a competent television repair technician be able to fix this fairly cheap (<$100) or should I pull the board and take it to a computer repair shop (or mail it to badcaps.net)?

[Wizard]

Re: Multiple TV's, multiple issues

Yes. No evidence. Listen to advises. I want you to replace vertical IC and capacitor, check the diode that is connected to this 100uF 35V capacitor.

Also trace back to the flyback with diodes and fusible/flameproof resistors from that anode side of that diode for the vertical IC to make sure resistor is not burned open and replace another capacitor there as well.

Cheers, Wizard