Samsung PS-42S4H flashing pixelated screen

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

Oh, that's nice. Like a work of art. must have good eyes. how much time did you spend doing that? Do you have a high quality SMD rework setup?

To remove I just used a hot air wand and plenty of flux, The hardest part is just making sure the grounding solder in the centre of this IC is melted enough so then the pins can become free from the pads at the same time.

To attach I just used my soldering iron with a fine tip and again plenty of flux. u need to make sure all remaining solder from the ground point under the IC is completely gone or the IC will not sit flat. Plenty of flux and Goot wick works good here.

whole removal and replacement mayb took an hour and a bit? not sure exactly as I removed this IC and cleaned up the board before my replacements came

[tw2005]

Re: Samsung PS-42S4H flashing pixelated screen

To remove I just used a hot air wand and plenty of flux, The hardest part is just making sure the grounding solder in the centre of this IC is melted enough so then the pins can become free from the pads at the same time.

To attach I just used my soldering iron with a fine tip and again plenty of flux. u need to make sure all remaining solder from the ground point under the IC is completely gone or the IC will not sit flat. Plenty of flux and Goot wick works good here.

whole removal and replacement mayb took an hour and a bit? not sure exactly as I removed this IC and cleaned up the board before my replacements came

yeah, took me a while to appreciate spending a few bucks on flux and quality wick. i use chem-wick from RS which wicks well as does goot. was it flux gel or just a pen?

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

yeah, took me a while to appreciate spending a few bucks on flux and quality wick. i use chem-wick from RS which wicks well as does goot. was it flux gel or just a pen?

Yeah its definitely worth the extra costs it helps so much on a number of things. Its a gel, I used amtec Lf-4300-tf its what I use for re-balling BGA's on ps3's for cleaning up.

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

If Vsch and floating 5V are ok you -should- be ok... the floating 5V will be measured from the floating GND to one of the small pins.
Still no guarantee here, as I don't fully understand how a Y-main can kill the buffers when it fails.

Tom can u confirm if the floating 5V is on the same connectors I was testing for Vsch voltages? cheers.

[tom66]

Re: Samsung PS-42S4H flashing pixelated screen

Tom can u confirm if the floating 5V is on the same connectors I was testing for Vsch voltages? cheers.

Yes, same connectors.

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

Yes, same connectors.

ok I have checked both connectors and I think I may have made a mistake before giving u incorrect VSCH readings so I have re read the thread again and have re tested following this post again.

I don't think I can see photobucket from my work PC. But I can see pics that newtothis have uploaded. Floating Vsch is last two right pins on this connector:
https://www.badcaps.net/forum/attach...0&d=1429608423

Measured wrt to the FGND pins on that connector, the majority of pins are on FGND.

Same on this but LEFT most two pins are Vsch;
https://www.badcaps.net/forum/attach...2&d=1429608423

On the 1st link above and on the outer most right pins (meter set on 200V) im getting readings of 7-7.5V

on the last link sent above but on the left most outer pins im getting the exact same readings.

The measurements on the floating ground is where I think I made my mistake and confused this reading with the above. So measurements here im now getting -141V.

does any of this change the fact the y drive board is good or not?

[tom66]

Re: Samsung PS-42S4H flashing pixelated screen

I think your previous measurements were in fact correct. If they weren't, that would be an unusual coincidence for you to be getting a nearly correct value. Also note Vsch is always positive.

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

I think your previous measurements were in fact correct. If they weren't, that would be an unusual coincidence for you to be getting a nearly correct value. Also note Vsch is always positive.

well I think I know where I went wrong in the testing now, my 1st measurements I gave I must have used the 200ACV setting not 200DCV setting on my meter. I just checked this to confirm and I get the same readings as the 1st measurements with the meter set on 200ACD and the 2nd lot or readings is with the meter set on 200DCV. sorry for the muck around and confusion hopefully this tells u something.

[tom66]

Re: Samsung PS-42S4H flashing pixelated screen

Yes, you should always use DC range.

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

Yes, you should always use DC range.

alright well since that is done then does that mean my 2nd readings are good and I can test the buffer boards back into the unit and see what happens?

[tom66]

Re: Samsung PS-42S4H flashing pixelated screen

Which set of readings? I'm lost.
If you get ~120-160VDC between FGND and Vsch you should be OK
Worth checking FGND+5V too, just in case.
I am not certain about these older sets, just going on what I know from some of the newer ones, so take that in mind...

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

ok I have checked both connectors and I think I may have made a mistake before giving u incorrect VSCH readings so I have re read the thread again and have re tested following this post again.



On the 1st link above and on the outer most right pins (meter set on 200V) im getting readings of 7-7.5V

on the last link sent above but on the left most outer pins im getting the exact same readings.

The measurements on the floating ground is where I think I made my mistake and confused this reading with the above. So measurements here im now getting -141V.

does any of this change the fact the y drive board is good or not?

Which set of readings? I'm lost.
If you get ~120-160VDC between FGND and Vsch you should be OK
Worth checking FGND+5V too, just in case.
I am not certain about these older sets, just going on what I know from some of the newer ones, so take that in mind...

These readings above this are the readings I got when my meter is set on 200DCV. (Not 200 ACV).

[tom66]

Re: Samsung PS-42S4H flashing pixelated screen

With BLACK on FGND and RED on appropriate pins, you should have a 5V and ~120-160V measurement on some groups of pins. If you don't there may be a problem. (Possibly the 5V could be higher and then regulated on the Y-buffer, but no higher than about 15V in)

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

With BLACK on FGND and RED on appropriate pins, you should have a 5V and ~120-160V measurement on some groups of pins. If you don't there may be a problem. (Possibly the 5V could be higher and then regulated on the Y-buffer, but no higher than about 15V in)

Hmm ok mayb this is where I was going wrong with my readings berfore? I was putting my black probe on the chassis ground and not the FGND points on the 2 connectors.

ok so I have just tested again with black probe on the FGND points this time and the red probe on the far outer pins on both connectors on the y drive board and I get 119.3V.

Left the black probe on the FGND points on the connectors and tested each other pin points that wasn't FGND pins and on both connectors the inner most pins both gave 5V. All other remaining pins that wasn't FGND pins or the 2 most inner pins gave readings anywhere between 0.8V- 4.3V.

im guessing this y drive board must be ok then huh?

[tom66]

Re: Samsung PS-42S4H flashing pixelated screen

Yes it would seem so, it seems like you have the Vsch, the 5V and some logic signals which are switching between reasonable levels.

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

Yes it would seem so, it seems like you have the Vsch, the 5V and some logic signals which are switching between reasonable levels.

ok then it looks like i'll hook it all back up and cross my fingers and see if we got somewhere with it haha will report soon.

[tw2005]

Re: Samsung PS-42S4H flashing pixelated screen

ok then it looks like i'll hook it all back up and cross my fingers and see if we got somewhere with it haha will report soon.

Please do , the suspense is killing me and I've runout of

good luck, hope it goes well or at worst no smoke, nothing pops.

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

Well good news is there was no pops and the IC's are not running hot (heat sinks still not attached yet) but I now get picture that's pixelated and fussy. At least its not switching on and off now

So what could these be? I read the cables that plug into the buffer boards can cause issues similar but I did re check these and plugged them in and out a few times just to be sure.

thoughts?



posted pic just for u too tom incase u cant see the pic from photobucket.

[tom66]

Re: Samsung PS-42S4H flashing pixelated screen

Can you check Vsch with the Y-buffer connected? Just to see if it's stable under load.

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

Can you check Vsch with the Y-buffer connected? Just to see if it's stable under load.

im getting 115.5V

So that's black probe on FGND and red probe on the 2 outer most pins on those buffer connectors.

I was actually wrong about those Buffer IC's with the TV sitting for longer periods, they are getting fairly hot to touch but I did notice the IC I changed is much cooler then the others but still warmish.

is it possible I need to go over my soldering again on the IC I changed?