Samsung PS-42S4H flashing pixelated screen

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

I can't see any pictures -- can you upload them here directly?

are you using pc to view them? ive uploaded them via photo bucket, if pics are not working do let me know, much appreciated, if they are not coming up i'll try upload directly but wasn't sure if the file size for best quality would be reduced?

cheers newtothis

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

pics working?

[tom66]

Re: Samsung PS-42S4H flashing pixelated screen

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

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

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

Ok thanks Tom for clearing that up so now I need to find out what the Vsch voltage is, to do this since I have removed the heat sinks from the mosfets on this y drive board, is it safe to do these test with these still removed or do they need to be put back on just for the tests? Also im guessing I'll need to remove the thermal compound from these but for the tests do I, or can I, just use normal thermal paste for now and then once confirmed readings or further tests have been done, then removed the thermal compound and use an adhesive thermal compound?

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

can any one chime in here on the above questions so I can do some further tests to report back to u guys? cheers

[newtothis]

Re: Samsung PS-42S4H flashing pixelated screen

OK I am not brilliant with Plasmas so will leave this to the others... But... Don't run anything that has a heatsink without it.. Most likely burn them up

[tom66]

Re: Samsung PS-42S4H flashing pixelated screen

I agree- the heatsink is there for a good reason

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

ok I have attached the heat sinks back to the Y drive board and have just used normal thermal paste between the heat sinks and mosfets, I guess this is better than having no heat sinks right?

I have connected the y drive board back up and connected all connections except for the top and bottom buffer boards.

The TV powers on with no clicking noises and remains on but of course with no picture because of the buffer boards not attached.

For some reason I couldn't get any readings with my positive probe on the outer pins on both connectors (floating VSCH) and the negative probe on the remaining pins that are linked together (FGND). not sure if I am doing this right so I changed multimeters to another that had an auto voltage reading but I found the voltage started at around 25V and continued to count down slowly to around 9V I didn't continue to watch the voltage do down further as I thought I must have been doing something wrong?

[tom66]

Re: Samsung PS-42S4H flashing pixelated screen

Low VSCH would cause problems similar to what you see.
It's worth trying to use a meter which you can lock in to a particular range, e.g. the 200VDC one, so you can see changes immediately.
Some autoranging meters can be slow to change ranges and hide sudden spikes in voltage.
Most autoranging meters allow you to lock the range using the RANGE button.

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

ok got my other meter that didn't work 1st time around to give me readings this time, I think its battery was dying and couldn't give full readings. anyways im now getting readings of 125.8V on both connectors on the y drive board.

[tom66]

Re: Samsung PS-42S4H flashing pixelated screen

That's a little low but within reasonable range - certainly wouldn't cause such a serious issue.
Must be another issue with the Y-main then.

[IMBack!]

Re: Samsung PS-42S4H flashing pixelated screen

Looks like you have the same issue as me. (https://www.badcaps.net/forum/showthread.php?t=45820). Very simular tv to.

Take a look at what i have measured/done

could you check your va ripple on the smps. ill take a look at my vsch.

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

That's a little low but within reasonable range - certainly wouldn't cause such a serious issue.
Must be another issue with the Y-main then.

what would be the next thing to check on the y main then?

Looks like you have the same issue as me. (https://www.badcaps.net/forum/showthread.php?t=45820). Very simular tv to.

Take a look at what i have measured/done

could you check your va ripple on the smps. ill take a look at my vsch.

I don't have the equipment to test what u have done sorry so I cant say what the va ripple is like.

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

any other input here on testing the Y drive board more in depth?

[tw2005]

Re: Samsung PS-42S4H flashing pixelated screen

any other input here on testing the Y drive board more in depth?

I'd love to help but I don't have enough knowledge on these. is there still a fault or are we just being very cautious before hooking the buffers up?

[wrx884]

Re: Samsung PS-42S4H flashing pixelated screen

I'd love to help but I don't have enough knowledge on these. is there still a fault or are we just being very cautious before hooking the buffers up?

well the bottom buffers IC blew for a reason yeah? so I guess im being cautious as these buffers are not the easiest IC's to replace, tho I do have some spares if needed.

[tom66]

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.

[tw2005]

Re: Samsung PS-42S4H flashing pixelated screen

well the bottom buffers IC blew for a reason yeah? so I guess im being cautious as these buffers are not the easiest IC's to replace, tho I do have some spares if needed.

yeah, age i'd say. everything has a life. It's 2005 so 10 year old could have over 20 000 hrs up. I think if you get this running and get into the service menu samsungs record the operating time as do the panasonics. I'm always interested to see what miles these have when they fail.

I was getting the impression Tom was leading into to saying it should be ok to try.

I usually worry more about the reverse that being are the buffers good so i don't destroy the ymain.

if you have some pics of the final repair of the buffers that would be good to see. Not something i've done but thinking about having a go

[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.

when u say one of the small pins, are we still talking on the same connectors where the FGND is on? (connector CN5002 and Connector CN5001?)

last question I guess before I hook these up to try and see what happens, these buffer IC's all had heat sinks on them, Do I need these in place for testing purposes or can I get away with not putting these on until im getting an actual clear picture? I have seen not all buffer boards even have heat sinks on them but mine do.

yeah, age i'd say. everything has a life. It's 2005 so 10 year old could have over 20 000 hrs up. I think if you get this running and get into the service menu samsungs record the operating time as do the panasonics. I'm always interested to see what miles these have when they fail.

I was getting the impression Tom was leading into to saying it should be ok to try.

I usually worry more about the reverse that being are the buffers good so i don't destroy the ymain.

if you have some pics of the final repair of the buffers that would be good to see. Not something i've done but thinking about having a go

good point I guess I would b lucky if this fires up with out any other issues but for some reason I just have a feeling its going to blow again but saying that you guys know more about this than me so fingers crossed LOL.

here are pics of these replaced IC I couldn't get real super clear shots so I have a few so u can see all pins on the IC at least.






ive tested for shorts and get nothing so I know my solder joins are not bridging anywhere at least

[tw2005]

Re: Samsung PS-42S4H flashing pixelated screen

when u say one of the small pins, are we still talking on the same connectors where the FGND is on? (connector CN5002 and Connector CN5001?)

last question I guess before I hook these up to try and see what happens, these buffer IC's all had heat sinks on them, Do I need these in place for testing purposes or can I get away with not putting these on until im getting an actual clear picture? I have seen not all buffer boards even have heat sinks on them but mine do.



good point I guess I would b lucky if this fires up with out any other issues but for some reason I just have a feeling its going to blow again but saying that you guys know more about this than me so fingers crossed LOL.

here are pics of these replaced IC I couldn't get real super clear shots so I have a few so u can see all pins on the IC at least.






ive tested for shorts and get nothing so I know my solder joins are not bridging anywhere at least

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?