Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

[Ancymon0]

Hello, My girlfriend parents had a samsung tv that "broke" couple years ago. They bough new one and were going to finally throw old one because it was taking place in garage, decided to take it to my home and try to check if it's possible to make it alive again as she has only 20' monitor

TV turns on, backlight is working fine, theres sound when i connect it by HDMI cable, but there is no picture at all.

I measured voltage on power supply board and it looks fine (just checking if its ok with description next to pins)

I found 2 faulty capacitors on power supply board, but i'm not sure if it wouldc cause that problem
1. cracked
2. puffy head, but didnt crack yet

Attaching also t-con board(CPT 320wb02c), im not specialist but i didn't see any obvious damage on it - still could be a problem, didnt know how to examine it




I would be pleased with any help

[vinceroger69]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

i would start by re capping the psu as capacitors can also fail with high esr etc and still look good once you have done that we can get you to do some voltage testing etc.

[Ancymon0]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

Is there any possibility that changing caps will fix the problem and everything will start working as intended?

[vinceroger69]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

a possibility yes on the t con board there shoud be a fuse what dc voltage do you get on each side of it ?

[Ancymon0]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

Sadly cannot find any fuse on the t-con board, i think i will have to find some service manual with schematics

#EDIT I think there is a fuse under 1R0 resistor (blue one with N on it - so small that i cannot read it clearly), there is continuity between ends, didnt try to measure voltage as im not sure if im touching proper thing

[vinceroger69]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

service manual

[dskall]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

Left side is where voltages are produced for t-con so fuse would be along lower left side. 12v

[Ancymon0]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

i measured that blue SMD which i suppose is fuse, there is a 12.3V on both ends. I dont see any other SMD that looks like fuse on that board

[dskall]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

Disconnect ribbon cables going to panel one at a time and see if you get picture.

[Ancymon0]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

diconnected
all connected, black screen with backlight working
1st ribbon disconnected, right half of screen went white
2nd ribbon, nothing changed
3rd ribbon, left side of screen got blue, green and brighter green colour
4th whole screen went black with backlight working

[Ancymon0]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

I was checking testing poits on left side of t-con board(there is problem with it, because i have no idea which one should give which voltage). Some of them look ok according to measurements made by people in web, but noone checked TP510 - i dont have any voltage here. there is also no voltage on TP1-3 and TP7

Wanted to check LVDS cable, but main boards listed in manual are different than the one i have ( BN94-01202A) and i dont know which pin is what for

[vinceroger69]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

diconnected
all connected, black screen with backlight working
1st ribbon disconnected, right half of screen went white
2nd ribbon, nothing changed
3rd ribbon, left side of screen got blue, green and brighter green colour
4th whole screen went black with backlight working

Dissconect both left ribbon cables what do you see on the screen? then put those two back and do the same on the right what do you see on that side

[Ancymon0]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

Two left disconnected - right part of screen gets white, left part of screen is black
Two right disconnected -, right is white, left is black but with one brighter vertical stripe

same if i restart tv

during that test i was playing youtube by hdmi so sound was still up on tv speakers

[vinceroger69]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

Two left disconnected - right part of screen gets white, left part of screen is black
Two right disconnected -, right is white, left is black but with one brighter vertical stripe

same if i restart tv

during that test i was playing youtube by hdmi so sound was still up on tv speakers

if this was my set i would try another t con board as there usually cheap if it does not work you can re sell it on ebay etc too get your money back.
Also change those capacitors on the psu too can you also upload a picture showing the whole top side of the psu

[Ancymon0]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

Top left is swollen and cracked one is on the right just below mainboard ribbon

[vinceroger69]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

yes there certainly bad so not sure if there causing your issues if this was my set i would change all the capacitors on the psu except the very large primary one if that dose not get the picture back then try a t con board

[Ancymon0]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

I found t-con on auction site. I will head to electro shop on monday, recap psu check and what will happen. If nothing changes i will probably order t-con. I will update topic with results
Thanks for assistance

[vinceroger69]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

make sure you try to get low esr capacitors 105c rated some of the cheap 85c rated general purpose ones may not work if you can get panasonic capacitors in the fc fm fr series you should be fine

[Ancymon0]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

I also found datasheet of my lcd panel so i might be able to check if there is signal between main board and t-con before i replace it if recapping of psu wont help. service manual for tv didnt include lcd panel and t-con board. (still have only multimeter, not osciloscope, but always something)

if anyone needs it in future i will make stamp for google search
Samsung LE32S71B
t-con 320WB02C SD
panel CHUNGHWA CLAA320WB02

[dskall]

Re: Samsung TV, sound ok, backlight ok, no picture - model LE32S71B

With voltmeter you may pick up some voltage on data lines to maybe confirm mainboard is sending data to t-con but no substitute for oscilloscope