Samsung LE23R86WD with vertical rainbow stripes

[seljer]

Hey guys. I found this TV in the dumpster with nothing other than a scratch on the base! If nothing else it had no business being in the bin marked for 'plastic'! It pays to recycle

Anyway, I brought it home it powered up fine but 98% of the time it only shows vertical rainbow stripes across the entire screen. Its like there some kind of jumpy connection or something because every so often if you're lucky you do get a flicker of the proper image (and the menus and such do work). It also seems to be stuck in a loop of shutting down and turning back on, with the screen going black, then white for a second, then the rainbow pattern for about 20 seconds. I've had more luck at getting normal operation when starting completly cold, but then it works for a minute or so then disappears.

I took it apart and reseated all the connections between the power/main/timing boards and sprayed in a bit of contact cleaner, as well reseating as the the two ribbon cables going from the timing control board to the panel (only at the t-con side, they're stuck in place on the LCD). It didn't really make any difference . The power supply caps at a glance seem to OK.

So what should my approach be to revive this thing? Replace the t-con board? or do a more thorough check of the power supply first?

[budm]

Re: Samsung LE23R86WD with vertical rainbow stripes

Can you read any voltages on the connectors between the power supply board and the main board? There should be some kind of voltage labels next to the connector.

[seljer]

Re: Samsung LE23R86WD with vertical rainbow stripes

Urgh, I need better multimeter probes. But here are the measurements:

nc	0	|	nc	0
12v	11.9	|	12v	11.9
12v	11.9	|	gnd	0
gnd	0	|	gnd	0
5.2v	5.35	|	5.3v	5.35
5.2v	5.35	|	5.3v	5.35
gnd	0	|	gnd	0
gnd	0	|	gnd	0
9.2v	9.1	|	9.2v	9.1
gnd	0	|	gnd	0
5.2v	5.2	|	gnd	0
ps_on	3.37	|	nc	0

The voltages start to fall when the TV shuts itself off for a second before it turns back on.

I've also got a 100Mhz oscilloscope if thats any help .

[budm]

Re: Samsung LE23R86WD with vertical rainbow stripes

OK, they are all OK, so it looks like you may have problem on the main board since the TV is stuck in the loop, but just to be sure, disconnect the LVDS cable between the main board and the T-CON to see if it still stuck in the loop.

[seljer]

Re: Samsung LE23R86WD with vertical rainbow stripes

It appears that I may be the one to blame for it because that symptom only started only some time after I put it back together after taking it apart (but it didn't start right away, it did function for a while )

If I disconnect the LVDS it's still looping, though its only evident through the changing backlight.

[seljer]

Re: Samsung LE23R86WD with vertical rainbow stripes

Fired it up again today. Confirmed that it does behave slightly better when cold. I'm able to get the image and menus (occasionally with some horizontal static lines) for about 3 minutes before its back to vertical rainbows.