Samsung LE32R87BDX

[anotherdude]

Replaced all the bulging caps on this tv's power board due to it not turning on, replaced the caps all seemed fine until i plug a device into the tv.

If i connect a hdmi or scart device to the tv there is sound distortion and picture distortion, if i turn it on with the device connected the tv reboots itself around 6 times before eventually everything clears up and the tv works as normal.

Been reading and reading and it seems the main board is at fault

any clues?

[cashkennedy]

Re: Samsung LE32R87BDX

I would recomend either testing (with an esr meter) or replacing the rest of the capacitors on the power board first, If that doesnt fix it, then likely a main board issue. Have you tested all the voltages leaving the power board with a volt meter? Does blowing hot air at either board make the problem go away faster?

[anotherdude]

Re: Samsung LE32R87BDX

no esr meter to test, theres only 1 large capacitor i haven't replaced

just tried a factory reset but didn't help, could it just be age power on time is 21143 hours

if i've had the tv on for the first few minutes and then turn it off for 10 minutes then back on the symptomns are not as bad, theres no restarting or bad sound but the picture remains distorted for a few more seconds then clears up

to me it seems like something is simply warming up or voltage isn't being regulated correctly

not tested the voltages yet, how am i supposed to know what they are ment to be?

there seems to be a lot of gunk around certain parts on the power board i know some of it looks normal (it's on similar components) but some not so much will get a picture later today

[anotherdude]

Re: Samsung LE32R87BDX

see the mosfet on this board looks damaged, but not got the tools to test

[anotherdude]

Re: Samsung LE32R87BDX

so i removed the glue from around the mosfet after reading about the glue being conductive when it turns brown, it was hollow and it looks like it's ate away at the mosfet legs

need changing?

[tom66]

Re: Samsung LE32R87BDX

Those "SD" capacitors are NOT suitable for a switching power supply! Let me guess... Rapid Electronics? eBay? I use Panasonic and Rubycon which are rated for SMPS use due to their low ESR.

[anotherdude]

Re: Samsung LE32R87BDX

Those "SD" capacitors are NOT suitable for a switching power supply! Let me guess... Rapid Electronics? eBay? I use Panasonic and Rubycon which are rated for SMPS use due to their low ESR.

actually what it was that maplin didn't have a replacement 10v and i originally had a 25v one in there (not sd and rated at 105c) same uf rating but got the same issue with this 1 too so guess thats not the issue

or am i wrong to assume that the voltage doesnt matter on caps and that the uf rating is important?

also the brown mosfet seems to have no continuity in circuit whereas others do

the mosfet/transistor thats dead i can't find anywhere cheap enough for it the original is 512-KSD526Y

and these are the replacments i can find but there £10 for postage no idea if i'm even on the right track here but it seems dead

863-BD442 512-KSD526Y 512-KSD1408YTU

[Foppel]

Re: Samsung LE32R87BDX

Have you tried to resoldering and cleaning the glued Transistor QB802? You can use Isopropanol to clean the Transistor. See: https://www.badcaps.net/forum/showthread.php?t=22470 Maybe you can use a heat gun (or hair dryer) and Cooling Spray to locate the faulty parts.

schematic: https://cdn.badcaps-static.com/pdfs/...b225f06d1f.pdf

Please give us a picture of the bottom side of the board. Maybe we have bad soldering spots.

[tom66]

Re: Samsung LE32R87BDX

The capacitance is most important.
Voltage should be the same or higher except in very particular circumstances.

[anotherdude]

Re: Samsung LE32R87BDX

not got pictures of the underside atm but shouldn't there still be continuity from the transistor i've removed all the glue and my multimeter on other transistors on the board has conituity in circuit, this does not also does not out of circuit, if theres no continuity doesn't that mean the part is bad?

i followed this http://www.decibelcar.com/menuelectro/93.html and there is no continuity at any point

seem i might of put too much heat on one of the legs when removing the transistor it's left copper exposed other than that my soldering looks fine i think

anyone know where i can get a new transistor at a reasonable price and not £11 or anyone have one laying about? it's a d526-y

any reason that a possible dead transistor could cause the problems i'm having?

[anotherdude]

Re: Samsung LE32R87BDX

so i've gave up on that transistor doesn't seem to be the issue, i removed it and powered the tv on and i get nothing, guessing if it was at fault i'd get the same thing

anyway left the tv off for 10-15 minutes after putting the transistor back in and left it to cool

switched it back on and got the same thing again so got the hairdryer on the main av board and after maybe 10-20 seconds the picture clears up

a reflow in order maybe?

[vinceroger69]

Re: Samsung LE32R87BDX

can you pin point the exact area the heat affects it?

[anotherdude]

Re: Samsung LE32R87BDX

i will after liverpool win

[anotherdude]

Re: Samsung LE32R87BDX

so just got a chance to test it again and found it's this area i heat here for 5-10 seconds and the tv only reboots once and the picture and sound are fine

this was just with a hair dryer, i do own a heatgun if people think it's needed

[Foppel]

Re: Samsung LE32R87BDX

Hey Dude. I think it's not easy to remove the cover. But you can check the soldering spots. But sometimes the BGA chips lose the contact with the board and this is really hard to fix I tried to fix a bga processor from an Nintendo DS with a reflow soldering station. But i use too much heat and the CPU died ;( Good luck

[kevinm34232]

Re: Samsung LE32R87BDX

Can someone point to a thread on how to safely reflow a TV main board in an oven? I think Ill need to do one aswell..

[anotherdude]

Re: Samsung LE32R87BDX

Hey Dude. I think it's not easy to remove the cover. But you can check the soldering spots. But sometimes the BGA chips lose the contact with the board and this is really hard to fix I tried to fix a bga processor from an Nintendo DS with a reflow soldering station. But i use too much heat and the CPU died ;( Good luck

i don't think this is to the same degree as a hair dryer doesn't create that much heat with 10 seconds i'll take the board off the tv later and see if theres anything obvious, hoping for a cold joint

[vinceroger69]

Re: Samsung LE32R87BDX

or a bad capacitor under the Shield how easy it to unsolder the lid/top

[anotherdude]

Re: Samsung LE32R87BDX

ye i thought that too, took the shield off and theres nothing visible to say there bad

any help?

[Foppel]

Re: Samsung LE32R87BDX

You can check the caps with an ESR Meter but i think they are ok. You can carefully press with your finger on the BGA Chips and then you can see if its a bad contact.