Re: Samsung LN40B650T1F won't power on
bump
bump
-
-
Re: Samsung LN40B650T1F won't power on
Does the problem occur on all inputs? Does it affect the menus?Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
-
Re: Samsung LN40B650T1F won't power on
OK, before I could get back into trying to answer Tom's questions about the inputs, my friend informed me that the TV died while his wife was watching it. I have been reading posts and wanted to try to find out some information before posting back. Here is what I tried.
I have attached again power board photos, schematic from Tom, and datasheets for easy viewing.
TV is still at my friend's house. After replacing the bad CCFL, the TV worked fine, except for the aforementioned line. Then while viewing a program, the TV quit with no further signs of life. When plugged in there is nothing. Remote will not even light the power LED.
Had my buddy remove the back and told him to check fuses FS801S and FM802S on the power board. FS801S was good, FM802S was open. It is a 3.15A 250V ceramic fuse. I remembered reading a post by budm, and although I didn't really understand the theory, I made a 75W “test lamp” by soldering a bulb to a spent fuse and had my friend plug it in the fuse holder. I told him to watch the light. The light lit up very brightly as soon as the unit was plugged in to AC. See attachment if you wish. I told him if the lamp lit, to power off and then pull the connector to the ribbon cable from the power board at CNM802 and try again. Right or wrong, my thought was that would tell me if the problem was on the power board or farther down the line. The lamp lit up again. So upon getting that report, I figured the power board itself to be bad and told him to remove it and bring it to me. Budm would be proud as this time he left the sockets in the TV! (some earlier humor)
Armed with a meter, the schematic and not much knowledge except countless hours of reading Badcaps, this is what I found up to this point.
Q1821 reads shorted from G-S-D on ohms or diode mode.
Q1820 reads shorted from S-D, G-S and G-D read 120 or 138 depending on lead orientation.
QP801S and QP802S I would say are OK.
UM801S is nearby but didn't know what to do with him.
I would guess from previous reading to remove Q1820 and Q1821 from board and retest, but I would feel better with some advice before I get into trouble. Should I try to check anything else? Thanks in advance for any help.Attached FilesComment
-
-
Re: Samsung LN40B650T1F won't power on
bumpComment
-
Re: Samsung LN40B650T1F won't power on
fishingComment
-
Re: Samsung LN40B650T1F won't power on
I did remove QI801 from the board and it reads shorted everywhere. Guess I will try to find one. There was some sort of reinforcement in the through hole for that device. Is that typical?Comment
-
Re: Samsung LN40B650T1F won't power on
It is normal.
If this is like the other Samsung boards I remember this is a common fault.
You only need to replace the FETs - you can leave the other components alone because it is driven by transformer, so damage to the control ICs is rare.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
-
Re: Samsung LN40B650T1F won't power on
Thanks Tom. I just checked Digikey and Mouser and it seems this device is obsolete. I will see if there is an equivalent in these posts. Thanks again.
I think I recall July to be your start work month?Comment
-
Re: Samsung LN40B650T1F won't power on
I start on the 7th, so my availability for help over the next year will decrease significantly.
You only need to match a new FET to the following parameters: Qg same or less, Rds(ON) same or less, Vds same or higher, Id same or higher.Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
For service manual, schematic, boardview (board view), datasheet, cad - use our search.Comment
-
Re: Samsung LN40B650T1F won't power on
Thanks very much for the device info. I don't mind helping myself and with that information I think I can find a suitable replacement. Thanks again.
Good luck with your new job. I have no doubt they will never want to let you go. I (and everyone) will be hoping you have time to still hang out with us.Comment
-
Re: Samsung LN40B650T1F won't power on
Per Tom's post above I chose a Fairchild FDPF8N50NZU Mosfet as the replacement and replaced both QI820 and QI821. Sent the board back with my friend. He installed it last night and reported that the TV is working wonderfully. Thanks again to Tom and others who helped me learn so much during this adventure.Comment
-
Re: Samsung LN40B650T1F won't power on
i just came into one of these tv's and it also has the 3.15A fuse blown... thank you for taking the time to fix this tv and giving me a place to start
Don't fear the repair...Comment
-
Samsung LN46C630K1F – Intermittent Backlight, BN44-00341B Power Board
Summary for TL-DR readers:
• Backlight is intermittent, may come on with TV boot or not. No flickering, never fails during TV on.
• Have obtained Samsung schematic & service documents - Can upload if helpful.
• Have read ALL applicable threads
• C1818 and CP820 replaced as low hanging fruit
• CN802 data taken for normal and failed BL operation. SUMMARY: Pin 2 - 5vDet = 3.52 @normal, 0.0 @BL fail. Pin 6 - EPWM = 1.631 @normal, 1.058 @BL fail.
• VCC pin (18) of PFC... -
Vizio e601i-A3 - Has Sound and Display, But No Backlight - Bad Power Supply Board or Bad LED Bulbs ?I was given this TV from my great uncle. He said it just wouldn't turn on one day out of nowhere, replaced the TV, and gave it to me to possibly fix and use for myself.
Upon bringing it home and plugging it up, it showed a standby light.
I powered it on and without a flashlight, the display showed the "V" but the lighting is very dim, but visible.
The screen seems to blackout and stay black, but with a flashlight I can see the display.
With my Playstation 4 connected via HDMI, and running a game I can hear sound.
Assuming... -
[HELP] Acer AN515-55 (LA-J871P Rev: 1B) – Board won't power on after GPU investigation – Suspecting Super I/O or PCH
Hi everyone,
I'm working on an Acer Nitro 5 unit with the following specs:- Motherboard: LA-J871P Rev: 1B
- Model: Acer AN515-55-59MT
- S/N: NHQ7JAL00403906A973400
- SNID: 03902728734
Initial Issue
The laptop initially presented graphic issues and driver failure (Code 43) for the GPU.
After preventive maintenance (cleaning, thermal paste, etc.), it powered on normally. We disassembled it again to inspect the GPU, reassembled... -
Hi and thanks in advance for any input you might provide!
I have a Sceptre U550CV-UMRD8POTV83BB 4K LED (this is a dumb tv) that I bought new in August 2021, so It's just completed 3 years.
Main power board model: TP.MS3683.PC821 T-Con board: N4TP546UHDPU2L_BO
Last Sunday I was watching a dvd and fell asleep for about half hour, when I awoke the tv screen was black and couldn't get the dvd menu to show, so I changed the input to antenna and had sound but no picture, turned it off. I then got online and found this great site! ....read many troubleshooting tips and this... -
I did not have any 27uf @ 50 volt capacitors but one nice thing is that it has enough room for two capacitors in parallel a 22uf and a 4.7uf @ 50 volts 22 plus 4.7 equals 26.7uf which so very close to 27uf I will show some pictures of it sometime tomorrow
This is one of the shit est boards I seen in a very long time and it was the daughter board the traces just lifting off the board I had to use the capacitor leads to repair the the traces and the main board is not any better because I had to repair several traces for the daughter board to the main board
After all of...
Comment