At this point I wouldn't be surprised, that seems to make sense. One end of the adjustment range does indeed seem to trigger the protection circuit while the other leads to blinking & drop-out.
On reflection I think there's going to be a replacement TV in our future, it's been interesting and a learning experience which is a lot of what this is about but probably time to cut bait. Since I just can't leave well enough alone, (LOL!) I'm contemplating an LED backlight retrofit just for the fun of it but that would make it a secondary TV, not the primary that has to be depended...
C152Heavy
Senior Member
Last Activity: 01-21-2024, 10:11 PM
Joined: 05-23-2014
Location: East
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Thanks, that's an interesting thread. I'll file that away in case I have a CFL that goes west.
Just to underline though, the resistor I'm speaking of is part of the PFC circuit not at the CFL board so I don't think the thread is directly applicable.
D 😎...Leave a comment:
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OP Update:
I see that it's been almost exactly a year since I last posted but I have news worthy of an update. So many of these threads just go quiet, like this one, with no eventual outcome reported but I think I owe it to all that have helped with advice along the way and those attempting to solve the same problem to report back on the final outcome.
[B]I FIXED IT![/B] (Hopefully for good) 😀😁😄😎
If you've read this thread this far then you have seen everything I have done to try and fix this thing. In the past year we have been tolerating the...Last edited by C152Heavy; 01-17-2024, 11:59 AM.Leave a comment:
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Re: Samsung LN46C630K1F – Intermittent Backlight, BN44-00341B Power Board
On 12 Jan., R_J said:
Thinking back, I looked around the HV transformers on the Power Board (solder joints) and didn't see anything suspicious. I was looking at the distribution board for bad CFLs etc. and I didn't see anything else that stood out but I wasn't looking specifically for bad connections so I'll put that on the to do list, thanks for the reminder.
Are we looking for a bad connection that keeps the current from flowing to or on the distribution...Leave a comment:
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Re: Samsung LN46C630K1F – Intermittent Backlight, BN44-00341B Power Board
OK, what is the "magic" procedure? Pull the plug, hold the remote start button down for 30 seconds? Once the capacitors drain (almost instantly) isn't the button hold time not relevant?
What is supposed to be occurring when the button hold procedure is done? Some sort of a mini re-set?
I'm not trying to be smart here, just wanting to understand what's being achieved.
Thanks,
C152Heavy
...
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Re: Samsung LN46C630K1F – Intermittent Backlight, BN44-00341B Power Board
Ummmm..., Sorry, I'm not getting whether you're joking on serious....
C152Heavy...
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Re: Samsung LN46C630K1F – Intermittent Backlight, BN44-00341B Power Board
LOL! Well, sort of, not really.
All I did was press the button a few seconds as if I was starting the TV. I had noted previously, when I had test leads on the two 100u/450 caps, doing that drained those caps leaving no residual energy on the board.
So, no attempts at "magic" repairs.
C152Heavy...
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Re: Samsung LN46C630K1F – Intermittent Backlight, BN44-00341B Power Board
Update:
Since it's been back in service the BL has failed once and wouldn't light for a few ON/OFF power cycles so I pulled the mains plug plus hit the "on" button which drains the two 100u/450V caps/residual power in the system and it has been behaving since.
No idea why that should help and no idea if it would again but it's about all I could do at that point!
Too bad these things don't have a OBD like cars, LOL!
D
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Re: Samsung LN46C630K1F – Intermittent Backlight, BN44-00341B Power Board
Hmmm.... Is the idea to provoke the protection circuit and shut down the TV or to see if the BL fails on the next on/off cycle?
Thanks,
C152Heavy...
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Re: Samsung LN46C630K1F – Intermittent Backlight, BN44-00341B Power Board
Update:
The TV has been on the bench since last post. I have made the measurements suggested in the two Youtube videos with no apparent anomalies. The voltages measured were consistent from transformer to transformer although different values from the videos posted.
I am convinced that the transformers and CCFLs are not the problem for one clear reason, the TV does NOT shut down as would happen if the protection circuit was activated. That was shown in this video, one of two suggested...Leave a comment:
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Re: Samsung LN46C630K1F – Intermittent Backlight, BN44-00341B Power Board
Actually, I replaced all electrolytics except CM 805, 813, 815, 818, 819, those are on tap for arrival of a shipment from Digikey that I'm looking for at the first of the week. Finger trouble got in the way of those in the first round.....
I was also thinking of caps when I mentioned potential "soft" components that would have reason to vary over time and interfere with operation.
C152Heavy...
Last edited by C152Heavy; 01-12-2023, 09:21 AM.Leave a comment:
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Re: Samsung LN46C630K1F – Intermittent Backlight, BN44-00341B Power Board
The backlight is generally working but fails to light on boot on occasion. It has never just quit while the TV was on.
My CN802 measurement table shows the values with both normal operation and BL fail. Pin 18 shows .877V with the back light lit and .862V with it failed.
I had a quick look at the distribution board this evening, no apparent problems but that was just a quick visual.
Thanks,
C152Heavy...
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Re: Samsung LN46C630K1F – Intermittent Backlight, BN44-00341B Power Board
Got a chance to get back to this, this evening. Pin 18 (PSON) measures 5.15V at the P Supply board with the cable disconnected and then the TV plugged in (BL on by default function).
Just so I understand, from your statement above you're saying that the P Supply board sends this signal to the Main board to turn on the PWR supply? I'm not following, shouldn't the main board command the P Supply to turn on or is it the P Supply board telling the Main board that the P Sup board...Leave a comment:
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Re: Samsung LN46C630K1F – Intermittent Backlight, BN44-00341B Power Board
I've run into suspicious joints on another Samsung transformer so there could be something to that.
Cutting down the weeds one at a time to find out what's in the yard!
Thanks,
C152Heavy...
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Re: Samsung LN46C630K1F – Intermittent Backlight, BN44-00341B Power Board
Thanks again, I'll address your series of messages here.
The videos on the transformers are another interesting lead to follow, thanks I'll think on that a bit now. Hard to proof a diagnosis if the TV continues to be intermittent and fickle when you want to see it fail under test!
Pin 18 on the cable is puzzling, I saw Budm's comment but I also saw another posting that had the value I got and that's while the TV is running correctly. Maybe the jury is still...Leave a comment:
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Re: Samsung LN46C630K1F – Intermittent Backlight, BN44-00341B Power Board
Thanks for your quick response!
I don't see any joints that are holding their hand up saying they are bad, they look pretty good (magnified lamp). Good thought though.
Would low voltage there be picked up by the V_SNS of IC1801 and shut down the drive to those transformers?
BTW, the low level squeal I hear, would that be normal as the BL is being established to run or is that an anomaly.
WRT the cable off, I did check (BL starts)...Leave a comment:
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Samsung LN46C630K1F – Intermittent Backlight, BN44-00341B Power Board
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, [B]0.0 @BL fail[/B]. Pin 6 - EPWM = 1.631 @normal, [B]1.058...Last edited by C152Heavy; 01-11-2023, 03:28 PM. -
Re: Samsung LN46C600F3FXZA No backlight
Just a quick note here to bring this thread back to the top after being dormant for the last 3 years, please add me to the list of appreciative people who have used the information here to repair their Samsung LN46 family of TVs, in my case it's an [B]LN46C630K1F[/B] with the same issue.
THANK YOU!
For posterity the backlight would sometimes not start on startup until it didn't start at all. Of course it always did it to the S.O. so I didn't have first hand info to work with.
In my case...Last edited by C152Heavy; 12-31-2022, 01:59 PM.Leave a comment:
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Re: Indetifying an Electronic Component - Help Pls.
Thanks, I'll follow that lead. When you say after the diode, you mean on the cathode side, correct?
I don't think the diode is open however, given that it is new and the replaced unit seemed to check OK.
Thanks,
D...
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UPDATE: Progress Report, Re: Indetifying an Electronic Component - Help Pls.
Reporting back after the initial round of repair.
I have 2 boards and started with the one appearing to be in better shape and having less of a damage history. I re-capped it, including repairing a few damaged tracks.
A word or two on the tracks; there was one track where a plated through hole just happened to be under one of the larger caps and this had failed on both boards many years ago prompting the jumper you see in the photos. Not knowing about leaking caps (this was...Leave a comment:
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