Re: Samsung 50" plasma PS50Q97 with a dead main board
Cap replaced. No improvement. I've discovered that my Y-Sus voltages do not match this document: [url]https://www.badcaps.net/forum/showpost.php?p=543670&postcount=40[/url]
I have 15V on almost all of the pins. At CN810 I have 206V for VS and the lowest pin on the connector has 15V. Does anyone know which voltage should be on that lowest pin on CN810? I will attach a picture of the connector.
Ok, so CN810 is:
VS: 206V
VS: 206V
GND
GND
GND
VG: 15V...
dokma
Member
Last Activity: 10-18-2023, 01:58 PM
Joined: 08-21-2017
Location: Zagreb, Grad Zagreb
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Re: Samsung 50" plasma PS50Q97 with a dead main board
Ok, new developments. I've been watching lots of videos on this particular model. This one was on the money: [url]https://www.youtube.com/watch?v=JjQ--2SZdyY&ab_channel=MrReeceyburger123[/url]
This is the cap that seems to have gone on mine: [url]https://youtu.be/JjQ--2SZdyY?t=650[/url]
I bought a cheap MG328 multifunction tester and found out that the cap from the video is 87uF instead of 680uF with an ESR value of 98 Ohms while it should have less than 0.02 Ohms or so. So my next step is to...Last edited by dokma; 12-31-2020, 03:28 PM.Leave a comment:
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Re: Samsung 50" plasma PS50Q97 with a dead main board
Finally got the control board. It took so long that I also managed to get one locally, so now I have two control boards. I've plugged the control board in and tried the test patterns by jumping PS-ON and pins 5 and 6 on the control board, as per post referred to earlier. I have also tried jumping pins 3 and 4 on the control board but the result is the same - no image on the display. The control board lights up one LED immediately on power on. After a second, another LED lights up. After an additional second, a third LED...Leave a comment:
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Re: Samsung 50" plasma PS50Q97 with a dead main board
Couldn't figure out what was wrong with the control board. The new one is on the way. My next concern is the Y-buffer. Any chance it survived a 19V spike on a 5.3V rail?Leave a comment:
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Re: Samsung 50" plasma PS50Q97 with a dead main board
I brought the control board to a motherboard repair service. The technician says it's probably not the Zener that I was suspecting and that I should flood the board from a battery instead? I have some 18650s laying around so I will try that. My frist attempt to find the shorted component failed because the resistance of the short is super low. Something like .1Ohm. I suspect the battery will fail to get anything hot at that resistance. But the tech insisted I should try it. I still suspect that Zener at the input. I think...Leave a comment:
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Re: Samsung 50" plasma PS50Q97 with a dead main board
So I tried to find the short on the control board by injecting voltage. Nothing gets warm even when I inject very large amperage, like over 3 amps at 5V. What is likely to cause this? Remember that the shorted 5.3V rail was exposed to 19V by the faulty power supply. What is the most likely to go short in this scenario in such a manner that nothing gets hot from over 3A at 5V?Leave a comment:
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Re: Samsung 50" plasma PS50Q97 with a dead main board
Looks like I wrongly identified my TV as PS50Q97HD. LJ41-05188A is likely the original board from this TV and that would make my TV actually a PS50C96HD. If I'm not mistaken again. Not having the sticker at the back is a pain...Leave a comment:
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Re: Samsung 50" plasma PS50Q97 with a dead main board
From my google "investigation" it appears that the control board LJ41-05188A that is in my TV at the moment comes from a PS50C96HD and that the one that should be in there is LJ41-04776A. I have no idea if LJ41-05188A is compatible with this model. It looks like someone figured out the fuse was blown on the control board, slapped a similar control board in and the fuse blew again due to 19V being present on 5.3V rail.
Is there any easy way to tell if LJ41-05188A is even compatible with this model...Leave a comment:
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Re: Samsung 50" plasma PS50Q97 with a dead main board
Some hopeful news again. The control board in the TV is: LJ41-05188A. I am not too sure if that is the original one or they tried to replace it and got it blown again. My control board has a blown fuse on the 5.3V rail. Let's hope the fuse protected everything behind it.
Can anyone confirm that this control board actually belongs to this TV?
...Leave a comment:
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Re: Samsung 50" plasma PS50Q97 with a dead main board
Nothing happens (other than the relay clicking on and staying on) when I plug everything up and jump pins 5 & 6 on the control board and PS_ON to ground on the power supply. I've identified that the compromised 5.3V rail goes to 3 boards: main board, control board and the long board along the bottom of the back side which I do not know what it is. I think I saw one blown up component on that long board across the bottom. I will try to investigate further tomorrow.Leave a comment:
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Re: Samsung 50" plasma PS50Q97 with a dead main board
For posterity: detailed test patterns instructions with tricks and pitfalls for this exact set: [url]https://www.badcaps.net/forum/showthread.php?p=735168[/url]Re: Samsung 50" plasma PS50Q97 with ...p=735168[/url]Leave a comment:
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Re: LG32LN5300 No standby voltage no power
Try checking the R103 and ZD105 feeding the startup voltage to the IC101. If they are leaking, IC101 could be on the way out.Leave a comment:
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Re: Samsung 50" plasma PS50Q97 with a dead main board
I found the instructions for this set somewhere on the forum a few weeks ago. I'll find them again and try to run them. I just hope the control board is not fried.Leave a comment:
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Re: Samsung 50" plasma PS50Q97 with a dead main board
The board connected to CN807 is fried. That is the one that flamed out. LJ92-01452A is the control board from what I understand. I hope that one is not fried and that it will be able to generate the test patterns. Is there any danger in just trying to generate the test patterns with what I have right now? From what I understand, I can run the test patterns without the board connecting to CN807. I just need a jumper and a resistor if I got it right....Leave a comment:
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Re: Vizio D55-f2 backlight/power supply 20v/24v rail output high 26v
You can check my thread where I've managed to fix 19V spikes on a 5.3V rail. My issue was a faulty switching voltage regulator on the power supply. Perhaps your issue is something similar.
[url]https://www.badcaps.net/forum/showthread.php?p=991809[/url]Re: Vizio D55-f2 backlight/power sup...aps your issueLeave a comment:
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Re: Samsung 50" plasma PS50Q97 with a dead main board
So I was right after all. It was the ICX802 MC33167. I replaced it with MC34167T-MOT in the same TO-220-5 packaging (which I found to be equivalent with 0% difference according to some site). Now I have stable 5.3V at the 5.3V test point and the power supply does not click off after I jump PS_ON and plug it in.
@Biruslapio - You saved me with that schematic!
TEST PATTERNS NEXT! I HOPE.Last edited by dokma; 09-30-2020, 11:12 AM.Leave a comment:
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Re: Samsung 50" plasma PS50Q97 with a dead main board
That is not a Zenner. It is a Schottky double diode rectifier. It cannot cause wrong voltage on the rail. Only the regulator can cause high voltage from the transformer to reach the 5.3V rail from what I understand (which is not much)....Leave a comment:
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Re: Samsung 50" plasma PS50Q97 with a dead main board
I think I'm using the terminology incorrectly. How do you call the board that is connected to the PSU via CN807? I referred to that board as main board.
The schematic you provided is really helpful. I'm betting on ICX802 going short and passing the transformer output current directly into the 5.3V rail. That probably also means that all the caps after ICX802 that are rated at 10V got fried. Will check if ICX802 gives same input and output voltages.
ICX802 is a 5 legged step down,...Leave a comment:
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Re: Samsung 50" plasma PS50Q97 with a dead main board
By tracing you mean going down the rail and checking all the components or is there more to it?...Leave a comment:
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Re: Samsung 50" plasma PS50Q97 with a dead main board
How does my 5.3V rail jump to 19V on power on???
So finally I got about to measuring things properly. These are the voltages I took from CN807 when the PSU is plugged into the mains and nothing else:
STBY : 5.11
VS-ON : 0
NC : 0
PS-ON : 4.19
RTN : 0
5.3V : 1.74
RTN : 0
RTN : 0
5.3V : 1.74
5.3V : 1.74
The 5.3V test point also gives 1.74V
Now the interesting part is the measurement I got when...Leave a comment:
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