2 Concertone 19"'s same problems

[Caryw]

Hi all, learned to recap monitors from here and now have these 2 problems sitting out in the shop.

model Concertone FR LCD-200T

I work for an RV dealer and we replaced these two 19" LCD tv's under warranty but they didnt even want them back.

Problem seems like bad caps but I cant see one that really jumps out at me.

Power light comes on green for the 4 seconds then goes back to red. I see no activity on the screen, in the dark or with a flashlight.

I do see this rusty looking stuff but it looks like a cheap glue job.

ideas.

[hardwareguy]

Re: 2 Concertone 19"'s same problems

A cap can fail with no outward signs. Also, one of the power regulators may have gone out.

You'll have to test more thoroughly. First order of business is testing voltages...is the PSU alright voltage wise? Low voltages suggest a short somewhere, possibly a shorted cap or transistor.

Next would be to get an ESR meter and test the caps.... or use an oscilloscope to check for excessive noise.

[Caryw]

Re: 2 Concertone 19"'s same problems

Ok, if you look at picture oo46 the 2 caps on that board are giving me readings in the 10 through 35 range, even though they are 470's, where the ones on the other board are giving within 25 +\- of the rating.

[hardwareguy]

Re: 2 Concertone 19"'s same problems

The uF on those is that low? If so, they are obviously bad.

Replace ALL caps of the same type that fail....the uF can be OK but the ESR can be out of spec. (even if they are good, they will likely fail soon)

[MixMasta]

Re: 2 Concertone 19"'s same problems

Since when can you test the capacitance while the cap is still soldered to the board and get the real value?

[Caryw]

Re: 2 Concertone 19"'s same problems

You know I was gonna ask myself that but being a rookie I didnt know.

I guess that makes sense. I tested the meter with known loose good caps and then those. I was more concerned with the snap on meter and not thinking.

Whoops.

[hardwareguy]

Re: 2 Concertone 19"'s same problems

Oh I was assuming you had desoldered them!

Yes, they must be tested out of circuit!