nashou
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Tech in Training.....
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Post by nashou on Apr 1, 2014 14:51:17 GMT -5
Well that's a drag. I'm learning too so pardon the following questions.... Could there be a short on one of the output pins at the IPM(s)? I mean, it sounds like you have good voltage going into the IPM but somewhere down stream of one of the outputs there's a short to gnd?...or possibly input voltage goes high after the set is powered on? Out of curiosity, are there any electromechanical relays in this set? And the fuse that blew...with no fuse in the holder you get no short to gnd on either side? Would it be a good thing to use lower rated fuses the next time you power up after installing new parts? Did you happen to check each IPMs pinouts for shorts to gnd when you had the IPM's out? I would hate to give up on it also if it were me. I guess if you can justify the time and expense for the greater good to learn it's cool but at some point I personally would have to consider any more money to be good money thrown at a bad cause and order new boards and accept the knock to my ego. But that's just me. lol We're rootin for ya bro! Well I tested the IPM before they went in. All tested good. Installed them and then checked the main connector where the PS voltages and GND come in for any shorts to GND incase it was not the old IPM's causing the Short. I also did this after I removed the IPM's and the location for them was un populated just to be sure. I like to make sure I didn't miss anything. The only relays are in the PS and I have that all tested and every voltage is present. With the Fuse removed It did not show a short on the board main connector in, checking the pins of the IPM it showed a short on GND to SU and ER( SU and ER are tied together on PCB) not to VS as it did on the first failure. So now thinking about it it has to be the Drive YB boards as the SU drives them and the PS pin is not shorted on the Chip. And since the VS was shorted on the IPM it is probably why the Fuse for the VS was blown on the PS board. So this is the plan. I'll get those 8 IPM's from china for 24 bucks, I'll have extra incase I mess up anything and or there may be a bad IPM in the batch. I'll install them and test the Set with the YB boards disconnected but the YSUS connected. If the set stays on and the YSUS does not blow a fuse or blow a fuse in the PS then I would have to assume two things. 1) one or both of the YB boards are bad and I should replace the chips. 2) the Panel is bad( but this is highly unlikely ). what do you guys think? |
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Post by mastertech on Apr 1, 2014 20:53:14 GMT -5
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nashou
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Tech in Training.....
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Post by nashou on Apr 2, 2014 15:56:25 GMT -5
Ok so I ordered 6 IPMs from china for 4 dollar each and 8 bucks shipping. So I'll have spares. I asked Mac a question off the forum about testing , here is his reply as I think it is good to keep it here for flow of my progress or lack thereof  So this is where I stand. Another 32 for IPM's PS is good X board Good, Y board bad after repair. The thing that gets me is the testing of the Buffer boards. I guess I will have to remove the glue off the pins and test the input side as Mac suggests in the quote above, but i did test the main connector pin as shown in this video. I also did the test to find a blown ic, but no shorts. So from all the reading ,viewing and research I have done I would say these Buffer boards are ok. now I know why plasmas are a pain. So once I get the new IPM's in i'll test with no Buffers connected. But would having the E buffer boards not connected blow the YSUS? I can't see how. |
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Post by mastertech on Apr 2, 2014 17:12:38 GMT -5
If you tested as in that video and there were no shorts then you should be ok. Unless you missed something, lol.
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nashou
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Tech in Training.....
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Post by nashou on Apr 2, 2014 17:25:56 GMT -5
If you tested as in that video and there were no shorts then you should be ok. Unless you missed something, lol. I think so too. I did remove some silicon, so I will have to cover it up again. Did not realize those little chips are getting 200 VDC from that paper you sent me. I think the YSUS might have been a bad repair. I'll remove the IPM's and look for any other shorts while they are out. I am still wondering about that lifted trace. If it went some where or not. there are two YSUS not working boards on ebay, one is 19 bucks( or make offer) and one 22. Both look like the IPM's were never removed. And one looks like 4 diodes were replaced(22 dollar one). 19 dollar one www.ebay.com/itm/SAMSUNG-Y-MAIN-BOARD-LJ92-01046A-996500030030-/141231868055?pt=US_TV_Boards_Parts_Components&hash=item20e2134897&autorefresh=true22 dollar one, this one you can see two blue diodes on each side near bottom of board. those are not stock from all the YSUS boards I looked at. www.ebay.com/itm/380874043564?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649I might off 10 bucks for the 19.99 one. why not if I can fix it i can sell it and maybe get some money back. Nashou |
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Post by justgreg on Apr 2, 2014 23:44:51 GMT -5
Man the way this thing is fighting you reminds me of my ex wife...without the alcohol. I guess I got off light with my plasma only needing 2 IPM's. Yeah I'd make low offers on those boards too, especially if you've never done the IC R&R before. Welp, on to the next chapter! Rock on bro. |
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nashou
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Tech in Training.....
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Post by nashou on Apr 3, 2014 9:44:57 GMT -5
Man the way this thing is fighting you reminds me of my ex wife...without the alcohol. I guess I got off light with my plasma only needing 2 IPM's. Yeah I'd make low offers on those boards too, especially if you've never done the IC R&R before. Welp, on to the next chapter! Rock on bro. I got a counter offer for 16 so I bought it. Who knows maybe the IPMs are fine on this board and there is another issue I can find. Wishful thinking. The 6 IPMs I ordered from China wont be here for a few weeks so we wait and see. In the mean time My sister will get a new TV and this one is mine. So I can at least use it I plan on bringing it to my restaurant. I hope she has the stand for it. Nashou |
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Post by mastertech on Apr 3, 2014 10:50:58 GMT -5
Yeah, and just think, once you get it running again and using it, after a year or 2 you will be starting this process all over again and you will be better versed in the testing procedures. Good thing you are ordering lots of extra parts.  |
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nashou
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Post by nashou on Apr 3, 2014 13:32:56 GMT -5
Yeah, and just think, once you get it running again and using it, after a year or 2 you will be starting this process all over again and you will be better versed in the testing procedures. Good thing you are ordering lots of extra parts. Lol, right Mac !!! What I think I'll do while waiting for parts is remove the IPM's and all the caps and test them. When I removed the first IPM's, I did heat the board a lot and on one of the large Caps the plastic cover bubbled from the heat maybe I cooked it. So I'll remove them all and measure them. Maybe that is what caused the short of the new IPM's. Nashou |
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Post by justgreg on Apr 3, 2014 14:56:11 GMT -5
And you'll have the time to put that lifted trace issue to rest so it stops being a factor in your diagnostics. lol
Are you going to add active cooling to each IPM before you button it up?
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nashou
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Tech in Training.....
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Post by nashou on Apr 5, 2014 16:37:01 GMT -5
Ok so the Spare board came in. IPM's are good!! Checked all Fets etc good!!! One bad Fuse it is one of those Green ones a 1 amp 250v . I can take one from my board and swap it in. F5004. These are near the YSUS outputs to the Buffer Drive boards. Now there are two SMD diodes near by. The one that is near the bad fuse shows Ok but the one near the good fuse shows short, so I think the fuse ties both ends of the diode together to show short when it really isn't. But as a lesson from before I will lift one end of the diode and test it. So I bet this board may have had a bad buffer connected to it and that fuse went and saved the IPM's. here is a pic of the fuse and D5023 that shows good. I just jumped that Fuse and the diode showed short so I was correct about the fuse tieing it in. 
So should I just replace that fuse and pop the board in and hope it works? lol I think I'll try it with no buffer board connected. then try one, then the other. No time right now so this will be later today or the next. Nashou |
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Post by mastertech on Apr 5, 2014 18:01:16 GMT -5
Did you check the supply inputs on this board for any shorts?
I don't know if I would try it without any buffers. Some things like a little load. But it is up to you. But remember, short on times for testing.
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nashou
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Tech in Training.....
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Post by nashou on Apr 5, 2014 18:09:43 GMT -5
Did you check the supply inputs on this board for any shorts? I don't know if I would try it without any buffers. Some things like a little load. But it is up to you. But remember, short on times for testing. I tested both sides, input and output connectors, no shorts. How long again for test times? no longer than 30 seconds? I think there is a way to have a white screen go on with no source but forgot where I can do that. Was it a jumper on the logic board? Nashou |
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Post by mastertech on Apr 5, 2014 19:24:42 GMT -5
That is only to try a forced video if you are having display problems. Until your unit stays on with no blinking leds no need for that. Your main concern is to get it to stay on with everything connected.
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nashou
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Tech in Training.....
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Post by nashou on Apr 5, 2014 19:26:16 GMT -5
Ok It powers up and I am getting an image with the jumper on the logic board . but it is a block type white screen and black. I can not see well though as I just have the top of the TV lifted on foam blocks about
6 inches off the floor.
So we have progress with this new board so far.
I'll check voltages again but there are some trim pots on the YSUS for adjusting. I am sure I got the PS correctly adjusted going by the sticker on the PDP.
How do I know what the YSUS should be?
EDIT:
Just saw your post, we posted together. well it stays on enough for me to see the pixelated block white and black screen.
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