Re: Transformer Identfication
Thank you. Here is a picture of a portion of the board. I could remove all the remnants if that would be of any help....
MEB
Badcaps Veteran
Last Activity: 10-16-2023, 10:44 PM
Joined: 09-18-2013
Location: Collinsville,Illinois
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Transformer Identfication
I don't know which section to put this question, but I frequent here and know you guys are most knowledgeable, so here goes. This transformer(?) is out of a Termiflex HT-2000 hand pendant. The resistor is shown to correlate size. It fell out when I opened the case. In lieu of trying to repair the broken case and leads, I wish to replace it. Can anyone help me to identify. The device operates on 5VDC. This is not my area of expertise as I have no area of expertise. Thank you.... -
Dell Precision 420 running NT
I have a 1990s era Dell Precision 420 Workstation running windows NT. Has been running fine since 1998. Now it shuts down very repeatably.
After lengthy troubleshooting, I have narrowed the problem down to the system shuts off almost immediately when any image is displayed on the monitor. The system will stay on indefinitely without a graphics card installed.
I have tried 2 different graphics cards, 3 different power supplies, 2 different hard drives with NT installed on each, different memory, applied new thermal grease to both processors and the only way to keep... -
HP C200 Workstation.
I know very little about this old stuff. Please be gentle.
I have a no boot situation on this workstation. LEDS on front panel are all (4) lit and solid. Manual from internet says that means system board. Is there anything I can do that might verify or dispute that failure? Thanks. -
Re: Samsung UN50F6300AF No Backlights
Sorry for the long delay, Work has been crazy. I put the new LED strips in and all is good, I turned the back lights down and my friend picked it up. I thank everyone and I learned some good stuff.
But I still have one question.
3~4 String 1 = 32 LEDs
5~6 String 2 = 32 LEDs
9~10 String 3 = 32 LEDs
11~12 String 4 = 48 LEDs
There are 2 Channels (Power supplys) so like bud said, 2 strings are connected in series. I can use the LED tester at the connector and test each string. But...Leave a comment:
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Re: Samsung UN50F6300AF No Backlights
Thanks, I will turn them down before I give it back. Strips are on order from SJ.Leave a comment:
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Re: Samsung UN50F6300AF No Backlights
Finally got in there and it was like everyone said. It kind of looked pretty much like neilc6's photos. Many shorted and open leds. Will order new strips today from SJ. While waiting I want to trace out those strips back to the pins as it is not readily visible to me about which strings are in series which each other. Their are 9 rows of 16 leds. There were 2 rows which were working and all the others were totally out or a few lit here and there. Will be back in a few days. Thanks....Leave a comment:
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Re: Samsung UN50F6300AF No Backlights
Thanks for the advice. I will let you know how it goesLeave a comment:
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Re: Samsung UN50F6300AF No Backlights
Ok, I used the LED tester to check the 4 strings. 3 of the 4 showed open and the other showed a voltage drop from 255 to 248. I guess it is time to open it up and test the LEDs and try to correlate the readings from the meter to the condition of the strings. Thanks to everyone. You have been most helpful. I will be back with the results.Leave a comment:
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Re: Samsung UN50F6300AF No Backlights
Thanks budm and neilc6 for help on the LED tester among other things. I will try to test the strings as you instructed and get back with findings.
budm - I am curious how you can use that LED tester as a voltmeter, not that I would want to. I thought it was just a low current power supply.Leave a comment:
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Re: Samsung UN50F6300AF No Backlights
R_J I have enclosed a picture of my meter. Should that be OK?
budm - D9151C = 264.9 black on cathode
0L red on cathode
D9251C = 265.1 black on cathode
0L red on cathode.
I started this thread because I wanted to know how to determine the state of the LEDs from the PS. It looks like we may have to put that on hold and use the LED tester. You guys can't tell me I told you so, because that wasn't on my initial agenda. but go ahead anyway. I am hoping now to use...Leave a comment:
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Re: Samsung UN50F6300AF No Backlights
Ok, I re-checked the measurements of CNL 802 with the led cable connected, black on chassis and powering up on every pin.
Same as before:
Pins 11 and 12 - jumps up to > 350V then drops rapidly to 0.
Pins 5 and 3 - jumps to > 400V then ramps up to a steady 437V
I forgot I loaned my soldering iron to my daughter so I will take the board to work and lift those diodes and report back.Leave a comment:
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Re: Samsung UN50F6300AF No Backlights
Sorry for the sporadic lateness of my replies. I have been working extended and crazy hours. I appreciate your guys promptness. I am again at work, but will get back to you on your test requests.
budm - I haven't but will check the resistance of diodes D9151C, D9251C in both direction with one leg lifted off the board. I will check my original readings again on CNL 802, and yes I have an LED tester. I have used it to check strings when they are out of the panel, never from the PSU because I can't tell what is going on when they...Leave a comment:
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Re: Samsung UN50F6300AF No Backlights
OK, still at it. Still confused. Please see my little drawing. That is how I think this is how it works, in my mind. if that is wrong let me know.
I took the measurements from the back of the board using the pin locations shown by budm. i don't understand this, but this is what i got. All measurements were taken with black on chassis and red on pins tuning power on each measurement.
Pin 12 - jumps up to about 350 V then drops to nothing.
Pin 10 - same as 12
Pin 5 - jumps to 400 V then climbs to 438V...Leave a comment:
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Re: Samsung UN50F6300AF No Backlights
Thanks budm and everyone. Once again I am at work and will get back to you.
I do understand checking the strings with a tester from the connector on the board, and I will, but right now I am learning great things which I want to understand first. I am a little stubborn, but mean no dis-respect. Please bear with me.Leave a comment:
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Re: Samsung UN50F6300AF No Backlights
Here are the 2 photos I am comparing. I can see the connector pin out is the same but little else. Maybe budm was just trying to show me the connector and not necessarily the surrounding board....Leave a comment:
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Re: Samsung UN50F6300AF No Backlights
OK, from the back of the board as shown, resistance between pins 4 and 5 is 0 ohms. From the back also, the resistance between pins 4 and 6 is 2.4 ohms. This is with nothing connected to the board. Note: my board and SJ photo are not the same as far as traces and components.Leave a comment:
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Re: Samsung UN50F6300AF No Backlights
I am totally confused. I understand why budm has problems with my values, because now understanding a bit more, I do too. But the problem remains as I checked them over and over and I am still getting the exact same thing. I am getting 440V on 3+ and 4+ with LEDs connected or disconnected which in my understanding is nearly impossible. Also with the cable to LEDs disconnected and probing the empty connector pins on the PS board, I get 2.4 ohms between pins 6 and 4 which are 3+ and 4+ which again can't be possible. Unless, the problem is not...Leave a comment:
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Re: Samsung UN50F6300AF No Backlights
Hello budm. I will recheck the numbers and also add the - pins. I have another question, but I will research a bit and run it by you later. Thanks.Leave a comment:
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Re: Samsung UN50F6300AF No Backlights
Thanks ngth82. I do have an led tester and will try that when I get home. This is currently a gray area for me. If there is an open led on string 1 and string 2 is in series with string 1, will the leds before the open one light up and nothing thereafter? And what would you expect if you had a shorted led? Would the rest of the string(s) light up except the shorted led? In the past when I have the display open and test the strips, I guess I haven't paid much attention to what actually happens. I guess I am just overjoyed to find a bad one after...Leave a comment:
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