Sanyo FW42D25T

[Jsikora]

Hi all, working on a Sanyo that powers up and has backlights but no picture. I checked voltages from LVDS cable and I am getting the low voltage 1-1.4V, but no higher voltage. I'm assuming that is why I'm not getting a picture. Also I am getting the proper voltage on the main cap. Any help would be appreciated. Thanks.

[dskall]

Re: Sanyo FW42D25T

What are you getting at your t-con fuse?

[Jsikora]

Re: Sanyo FW42D25T

T-con fuse is good. My problem is that I am not getting any voltage other than low coming off of the main board to the LVDS cable except low voltage. I tried the PS/Main on another identical TV with same panel that has a bad board and it does light the screen.

[Jsikora]

Re: Sanyo FW42D25T

So I am trying to figure out why I would be getting no 5V or 12V or anything close to that coming from the PS/Main to LVDS output.

[dick_barton]

Re: Sanyo FW42D25T

Have you checked the two regulators UL2 and the one below it.

[attainteddragon]

Re: Sanyo FW42D25T

you should have 12v on the t-con fuse, but the lvds, d/pairs are only low voltage and you really need a scope to see the signal.

if you do not have 12v on the t-con fuse, disconnect the t-con and see if the 12v comes up.

[Jsikora]

Re: Sanyo FW42D25T

UL1
5.21V
3.303V
0V
3.303V

UL2
5.21V
1.814v
0v
1.814v

T-Con fuse .223V

[dskall]

Re: Sanyo FW42D25T

T-con voltage probably originates off of main board through transistor

[Jsikora]

Re: Sanyo FW42D25T

Those are the voltages of the transistors UL1 and UL2 next to the plug for the LVDS cable.

[dskall]

Re: Sanyo FW42D25T

You have 12v marked on board at lvds connector. Need to trace back and find missing 12v

[Jsikora]

Re: Sanyo FW42D25T

I am hoping someone else has fixed this model as the PS is not available anywhere. Any idea of where to begin looking for problems on the board that would cause not getting 12V to LVDS?

[dskall]

Re: Sanyo FW42D25T

Ya read post 10

[nomoresonys]

Re: Sanyo FW42D25T

have one of these, had a slightly bulged 16 v 470 uf cap, replaced, tv will work ok for 30 seconds then it blanks out backlight and sound goes out, dont seem to be getting the boosted voltage at filter cap, is 170 when hit power button or in standby, wasn't getting backlights to light with tester, tore down to expose them, they all lit up wondering what voltages I should be getting on UL1 and UL2, in standby I guess, because it doesnt seem to want to stay powered up, maybe its a problem in the pfc section, not sure, any ideas?

[R_J]

Re: Sanyo FW42D25T

I don't believe this power supply has a pfc circuit, I would suspect the small vcc caps in the primary CB107, CB106? (the orange and black ones)

[nomoresonys]

Re: Sanyo FW42D25T

ok, I'll change those out, thanks RJ.

[lotas]

Re: Sanyo FW42D25T

what voltages I should be getting on UL1 and UL2?

3.3v, 1.8v.

[nomoresonys]

Re: Sanyo FW42D25T

Thanks Lotus.

[R_J]

Re: Sanyo FW42D25T

This is a link to a similar board

[nomoresonys]

Re: Sanyo FW42D25T

Thanks R J, I think I messed something up, I switched out those 2 caps, decided to put the screen back on but had a hard time fooling around with it, the whole frame seems to be really flimsy, might of cracked the screen not sure, instead of getting 30 seconds on, now I get nothing at all, not the first time I've gone in reverse trying to fix something.

[nomoresonys]

Re: Sanyo FW42D25T

think the panel didnt crack but its no wonder, was working on a small table thats easy to get around, almost dropped the whole thing off of it. With tv plugged in to power, the only voltage I get is 170 on filter cap and voltage on the big diodes next to it, seems to be no voltage at any connectors, no voltage on UL1 or UL2, guess I'll try switching out a few more electrolytics, my gm328a cap tester tests m pretty good out of circuit but for shit in circuit, no choice but to guess, maybe switch out the 4 green samxon caps.