Re: Sears SR2000 series, a classic in need of help!
No, no sign of that. I'm pretty sure the Commodore passed the surge along the grounded shielding of the composite video cable. Surge only occurred when that was hooked up, and area of damage being in the video input section of the board seems to confirm that....
teryaki
clicking HDD
Last Activity: 12-12-2018, 08:52 AM
Joined: 11-27-2017
Location: Cleveland, OH
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Re: Sears SR2000 series, a classic in need of help!
Got it apart and saw the problem soon as I flipped over the board. Surge must have traveled on the composite cable's shielding and gone into the ground trace. Two spots on the board where copper's been blown off that trace as it arced to the chassis and then down the ground wire in the power cable.
Components all look undamaged. Bunch of old Rubycon caps in here look like the day they left the factory +30-odd years of dust....Leave a comment:
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Re: Sears SR2000 series, a classic in need of help!
Thanks. Managed to get advice on safely discharging: have to ground the anode on the tube, which is under a suction-cup dealy at the top of the monitor....Leave a comment:
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Sears SR2000 series, a classic in need of help!
Hello! My girlfriend and I tried to set up her Commodore 64 today. Tried the living room TV and couldn't get a signal, so... we hooked up the CRT monitor, and the moment that she plugged the RCA video connection into the monitor, with a switched off C64 mind you, the lights dimmed and magic smoke was released.
Still don't know what happened.
Good news is the monitor will still power on, but doesn't take video inputs. I'm trying to get the board out to see where the magic smoke came from (video input is all the way at the front of the board).
I need someone... -
Re: Samsung PN50B650 plasma dark picture (better than what I started with)
You're a prince among men, at least this is something I can try....Leave a comment:
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Re: Samsung PN50B650 plasma dark picture (better than what I started with)
[url]https://imgur.com/4AP2Jdr[/url]
Thanks again.Re: Samsung PN50B650 plasma dark pic... Thanks again.Re: Samsung PN50B650 plasma dark picture (better than what I started with)
[url]https://imgur.com/4AP2Jdr[/url]
Thanks again....Leave a comment:
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Re: Samsung PN50B650 plasma dark picture (better than what I started with)
Was gonna put in a Mouser order anyhow, point out the Y board caps you think might be the issue? Not gonna be mad if it doesn't fix the issue, appreciate all the help, just grasping at straws because I don't want to just chuck out a good 50" 1080p plasma panel.
[url]http://assets.shopjimmy.com/media/catalog/product/cache/1/image/f8f28dc4a19c21aeb55ee5774693fb5d/s/h/shopjimmy-bn96-09744a-top_3.jpg[/url]
Power input is top left.Re: Samsung PN50B650 plasma dark picture...Last edited by teryaki; 12-30-2017, 03:15 PM.Leave a comment:
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Re: Samsung PN50B650 plasma dark picture (better than what I started with)
Man... so do you think a recap on the PS board would be a fool's errand?...Leave a comment:
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Re: Samsung PN50B650 plasma dark picture (better than what I started with)
Two different Y sustain boards, though. And a replaced Y-buffer....Leave a comment:
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Re: Samsung PN50B650 plasma dark picture (better than what I started with)
Ve and Va are perfect and stable. I've still got that dropoff on Vs as I measure closer to the Y board (can get 209 over by the X sustain board), and Vscan still fluctuates between -140 and -180, with spec being -200. The dropoff is more pronounced now, around 35v lower instead of the 20v dropoff I measured previously.
At this point both Y sustain and buffer boards have been replaced (Y sustain is going back since the old one worked just as well).Last edited by teryaki; 12-27-2017, 04:48 PM.Leave a comment:
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Re: Samsung PN50B650 plasma dark picture (better than what I started with)
I tried with a second Y-sus board, and Vs seems to get worse week after week. Seems like something on the PSU is dying?Leave a comment:
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Re: Samsung PN50B650 plasma dark picture (better than what I started with)
No o-scope, no. Also it's not the opto, the reading was because there's a 2k ohm resistor across the LED side of that opto.
But I think I've got something! I probed Vs again yesterday probing at different points, and I've got a sharp voltage drop! On the side of the power supply board near Z-sustain, it's reading 212v at the test point and at the connector to Z-sus board. But on the other side of the power supply board, at the pins connector for Y-sus, it's dropped to 202v. At the...Leave a comment:
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Re: Samsung PN50B650 plasma dark picture (better than what I started with)
SO! I checked all the big heatsinked diodes and transistors on the Y sustain board and they seemed consistent. So I started tracing circuits, and got to an optocoupler near a DIP-8 IC, both just upstream of the Vscan trim pot.
Diode test across the LED side of the optocoupler reads both ways (.774 anode to cathode, .788 cathode to anode. Does it sound like I've found my missing voltage?
Photo for reference, the optocoupler is U5013, in the far left of the image: [url]https://i.i...Leave a comment:
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Re: Samsung PN50B650 plasma dark picture (better than what I started with)
So Tom, at this point... start pulling and testing caps and transistors from the Y board? I don't know what else I can try.
EDIT: Looked up the board on ShopJimmy, they're indicating that the most common failure with that board isn't the caps: [url]https://www.shopjimmy.com/samsung-bn96-09744a-y-main-board-component-repair-kit.htm[/url]Re: Samsung PN50B650 plasma dark pic...nd transistorsLast edited by teryaki; 11-30-2017, 06:37 PM.Leave a comment:
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Re: Samsung PN50B650 plasma dark picture (better than what I started with)
Definitely a 2k pot. Stock pot is 2.05k ohms tested, 2.03k for the replacement.
Vsc is the same with the Y buffer board removed, -165v.Leave a comment:
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Re: Samsung PN50B650 plasma dark picture (better than what I started with)
Sorry, I'm usually pretty tired when I write these. Should definitely be 2k, not 200k. 20 + two zeros after that by marking conventions.
Sure I still have the original, I can check them against each other. And I'll pull the buffer and see where Vsc goes....Leave a comment:
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Re: Samsung PN50B650 plasma dark picture (better than what I started with)
Original was marked 202, that should be a 2k ohm pot. Replaced with same.
Thanks for chiming in, BTW. Just going through the stickied stuff here, you're a legend.Leave a comment:
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Re: Samsung PN50B650 plasma dark picture (better than what I started with)
[B]Panel[/B]
Va 56
Vsc -200
Vs 209
Ve 92
[B]Current values according to my multimeter[/B]
Va 57
[I]Vsc -162[/I]
Vs 209
Ve 94
I can't get Vsc to go any higher, 200k pot is turned all the way. Other way takes it to -54.Re: Samsung PN50B650 plasma dark picture (better than what I started with)
[B]Panel[/B]
Va 56
Vsc -200
Vs 209
Ve 92
...Leave a comment:
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Re: Samsung PN50B650 plasma dark picture (better than what I started with)
So when I said I had the voltages set per sticker... well, I certainly had sustain voltage set to what I thought was close enough. Panel sticker calls for 209v and I was getting 205v and figured that must be within tolerance, right? Probably my Home Depot multimeter's not precise enough to tell anyhow.
So I got the advice that it was probably sustain voltage being too low, so I measured. 205v. Turned it up, and can get a 207v measurement with the pot fully open.Last edited by teryaki; 11-27-2017, 07:09 PM.Leave a comment:
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Re: New T.V.!!! $60 60inch Vizio Smart T.V. Burnt LEDs, Easy Fix!!!
Today I learned!...Leave a comment:
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