Samsung le32a457/c1d new caps but t-com fuse issue

[wilson_campbell]

Hi all,

New to working with TV etc so if I make any mistakes in my terms that is why

Had the usual problem with with samsung caps (red light flashing but no power). Sometimes would eventually come on and sometime quickly and sometime not at all.

did following:

Only 1 was cap on cold side of power board visually gone so replace it but issue remained.

Replaced all the major caps plus resoldered some poor solders on npn transistor qb802. Then had no pic but sound + black light working.

With power on and not in standby: Checked all connectors going into control board from power board, all voltages match on main ribbon connector. On smaller connector :
blu = 5.21
adtm = 3.43
pwm = 4.9
gnd = 0
+bv = 5.39

Identified T-com 3am smd fuse blown. Checked AMPs and seemed to spike. Pulled and checked npn transistor qb802 with multimeter and all OK. Resoldered. Spike seemed to be gone. Replaced fuse and tried again but fuse blow again.

Would anyone have advice on where to proceed from here. All solder joints seem ok.

I would be greatfull if someone could also confirm the following is normal: When measuring amps at the power board connector for (ps)or at the t-conn fuse the minute I touch them the tv resets itself as if going from standby to on again. I can only think that the multimeter when reading amps is pulling out enough power that the control unit is sent into sandby mode because of the drop in power.

You help would be greatfully appreciated as my kids are driving me made as it is now 2 weeks since it broke

Sorry no pics as everytime I try to upload pics it finishes the upload but does nothing. Will try again later.

[wilson_campbell]

Re: Samsung le32a457/c1d new caps but t-com fuse issue

Pics of power board and control board now attached

[chrismurphy]

Re: Samsung le32a457/c1d new caps but t-com fuse issue

replace T-con board (main board)

[wilson_campbell]

Re: Samsung le32a457/c1d new caps but t-com fuse issue

hi,

The t-con was working before I replaced the caps in the power board. Would it just be a coincidence that the t-conn has now gone or is something in the powerboard causing/caused the issue.

My be a moot point now as when I was checking the amps again on the t-con fus, I held the millimetre probe on it for longer and some of the resisters on the control board nearly caught fire and was smoking. Controller board now probably fried.

[CapLeaker]

Re: Samsung le32a457/c1d new caps but t-com fuse issue

Yep. There is a dead short somewhere.

[wilson_campbell]

Re: Samsung le32a457/c1d new caps but t-com fuse issue

Thanks )

Strange. The parts that overheated where on the separate control board (board seems to still working as sound still there). The parts I changed/resolder where on the different power supply board. The power supply is generating the correct volts at the pins from the power supply. Although I am not sure about the correct voltages for the smaller connector going from the power board to the control board (not stated on board).

If I had caused a short circuit in the powerboard would the pins show correct voltage etc. + then cause a dead short on the control board.

[sordids999]

Re: Samsung le32a457/c1d new caps but t-com fuse issue

remove all the yellow glue on the power board it can become conductive over a period of time

[wilson_campbell]

Re: Samsung le32a457/c1d new caps but t-com fuse issue

Thanks

Removed the glue around the NPN transister (will do rest later) and now the fuse is not blowing each time.

Have picture now but just multicolour vertical lines and does not show tv/menu image at all. Would I be correct in saying this means the t-con is fried (did try receding the ribbon cables into the t-con).