Thank you very much...I needed to hear that from experienced pro.
I'll sleep over it (some of it I can actually remember from my voltage multipliers course in college) and will get to test when other work clears up, then report here. I firmly believe one has to give if they take.
Very rarely seen bad film capacitors in TV power board BTW. Can't say never, but definitely rarely.
Fluke 87v and Tektronix scope are my measuring devices and I'd put my life on them if I have to....I am not rich enough to use cheap tools.
20 years into it I still say a silent...
CoppellTVRepair
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Last Activity: 03-22-2025, 09:53 PM
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Troubleshooting PFC with SPC1012T not raising output
It has been a long while since I posted here to ask anything....hope you can help.
I have this Samsung power supply that uses SPC1012T as driver for the PFC and it's giving me a problem that I can't narrow down though I've troubleshooted and fixed hundreds of boards similar circuits.
I am attaching a schematic from a different Samsung board, but the topography is very very similar if not 100% the same and it uses SPC1012T, which BTW is a pinout match to UCC28063 for which there's plenty of information. I haven't confirmed they are functional equivalents, but I strongly... -
Re: I need bios eeprom LG 34UM68 EAX66876002
You get it off a working board.
More importantly, though, you most likely do NOT need it...you just do not know it yet.Leave a comment:
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Re: Samsung UN50NU6950FXZA ( All In One )
For anyone reading this thread I do not think you are on the right track looking into SLM4683A for the problem you describe.
The IC is an inverter driver as can be easily guessed if you look the area of the board it's occupying - it takes the rectified 13V output out of secondary of the main transformer and drives two MOSFETs , which in turn take power from another secondary through bridge rectifier.
I *guess* it may be possible for one to see what you're seeing with a certain defect in the IC, but what I've...Leave a comment:
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Re: Mitsubishi Lt-46164
Since we now offer repair for LT-46164 and the other main boards in the family I can clarify a few things to buy me (I hope) the right to post the below link:
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First (commenting on past comments) EEPROM failures are NOT at all foreign to those boards; they are not the most common issues, true, but they still do happen; they happen in later TV models as well, depending on architecture and design, so it is not like they are something that's left in the past.
NAND flash EEPROMs can get 1 single block corrupt and...Leave a comment:
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Re: Intermittent Power On LG 47LV5400-UB
I'd like to comment on that.
There are a few sellers out there who offer repair kits for practically any board they've heard of; if there are SMD capacitors they'll include them and if there are 1117 voltage stabilizes they'll likely include them too.
I have personally received customer's board with a vendor's repair kit consisting of capacitors and 1117 regulators that I have NEVER EVER seen fail on a particular Sanyo main board.
Simply put, there are a lot of vendors that are...Leave a comment:
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Re: Intermittent Power On LG 47LV5400-UB
Go straight to the main processor.
Board has a standby which rarely ever goes bad and main which BGA usually degrades and needs to be replaced.
[url]http://www.coppelltvrepair.com/p/1626/ebt61542604-61542604-main-board-repair-service-from-lg-47lv5400-ubausylhr-led-tv[/url]Re: Intermittent Power On LG 47LV540.../> [url]http:Leave a comment:
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Responding here, albiet with significant delay, for hopefully the benefit of those still in need.
We're component level service center for TV boards and since there's a particular shortage on market for particular board for The NS-P501Q-10A I am allowing myself to plug in here.
The two most common failures in NS-P501Q-10A are the X-Main LJ92-01688A and the Y-Main LJ92-01689A boards.
They fail independently from each other, just because of wearing out (yes, electronics wear out, due to thermal cycles of expansion and contraction of semiconductor...Last edited by SMDFlea; 04-09-2023, 04:37 AM.Leave a comment:
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Re: Vizio xvt472sv - PSON Always has Voltage
Just for the record, most of the times when a main board starts automatically (BL_ON activates almost instantly) 99% of the time the problem is in the main processor, which never actually starts up properly.
Seen it happen many times on various boards and for some reason always with MediaTek MT processors as opposed to, say, the Broadcom BCM ones.
- bobbyLeave a comment:
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Re: Vizio XVT423SV
1) Disconnect from AC, wait 2-3 minutes. Less if you disconnect main from power where DC is held by caps longer.
Hold down the rocker (power on) and connect the AC; wait until you see the "V" on the screen then release.
This, to the best of my knowledge, is factory reset settings for the family.
(you can also try it from the config menu, but as I understand this is better)
2) You can just replace the whole EEPROM on the main and all settings will get replaced along with it.
On a side...Leave a comment:
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Re: Difference Between BN44-00445a and BN44-00445c Power Supply
I do not mean to pick on you, but this is definitely an overstatement.
First, there are many different reasons for moving from one revision to another and not necessarily (or even mostly) finding problems in a given revision.
Second, nothing guarantees that the later revision will have less issues than the original.
In particular I've seen MUCH more BN44-00445C bad boards than BN44-00445A ones.
Note it doesn't mean the C is...Leave a comment:
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Re: Sony KDL-55NX720 blinks 4 times
Spent some time today troubleshooting a KDL-55NX720 with screen coming up for 4-5 seconds and then shutting off.
Haven't figured it out yet, partially because of Sony's idiotic design where if anything is disconnected (or failed) the whole TV shuts down and partially because, as usual, I was hacking and reverse-engineering my way around it without consulting any service manuals or schematics.
What I found today and what may help others in the unlikely event that I won't figure it out and the more likely that I don't...Leave a comment:
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Re: Dell w4201c hd pdp hdtv plasma tv
Just read that and I can't say I agree with it.
4 zener diodes in a row @ 5.1V each make zener of 20V.
They are on the sustain output where voltage is easily Vs at peak, i.e. over 100.
Have you actually tried putting 5V zeners there?
because I think they'll fry right away....Leave a comment:
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Re: vizio stuck on logo model m470nv
We've seen that happen due to bad EEPROM/firmware IC as well as because of a shorted HDMI multiplexor.
Both are available online for DIY repair , but both carry the risk of NOT being the source for the shutdown in your particular case. Although less likely, the main processor could also be bad, for example, as it is fairly complex and it may be able to start and execute the firmware all right, but a section of it handling the HDMI or LED driver control could fail to initialie/communicate with the core at a later initialization stage....Last edited by SMDFlea; 04-09-2023, 04:41 AM.Leave a comment:
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Re: Vizio M470NV - Blinking logo
We have seen a few different reasons for main board failure since we started offering a repair service for them about 4 months ago:
1) HDMI multiplexor Sil3985CTU is one of the, sometimes along with surrounding components;
2) Flash NAND IC U6 can get corrupt and cause all kinds of problems from totally dead TV (we've seen an IC with all blocks being bad straight off the board) to issues like failing to start the Vizio apps. The later suggests it doesn't have built-in checksum check otherwise it would not be starting...Leave a comment:
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Re: Samsung PN60E550D1F no audio no image only red LED
I read that thread while researching repair for the YSUS.
We are repair service center and you can quote this if you want: there are companies out there - ShipJimmy being among them - that offer repair kits that are highly unlikely to be based on first hand experience repairing boards.
There are boards that we've repaired hundreds of and I NEVER, I mean NEVER have seen particular parts fail that are being offered as a repair kit.
Which is not to say that *everything* they sell is...Leave a comment:
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Re: Vizio Eeprom location on main board??
Just to clarify something that is clearly sounding confusing at best: the eeprom type has nothing to do with whether the TV is smart or not.
"Eeprom" is, in fact, even not the proper term for the memory because it can be different type, but that's another story.
The point is that smart TVs can use regular eeprom ICs with as little as 8 pins and regular TVs can use NAND flash memories with partitioning.
The programmers for those are more expensive at the moment, but time will sure take...Leave a comment:
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Re: Another cycling, screeching Samsung plasma.
You have a bad power supply board.
Reflowing will not help because what's bad is not a junction, but a component.
Reflowing, like a sirgical operation, is a risky process. It can save from dying (or , in electrical world, the dead), but it may also kill the living.
It is the last thing I'd do unless I have a reliable history of a particular failure on a particular board, like the three lights of death on XBOX or image deformations on older laptops.
The source of this problem...Leave a comment:
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Re: Samsung pn58a550s1fxza powers on, no picture
Sorry for the brief post, but I just had a failure trying to post a long and more detailed one and that got me upset.
First, having sound, but no image is rarely a power supply board problem, except in some of the older power supplies which allow Vs to go low unnoticed; most modern supplies would shut off if Vs goes out of range in either direction.
That said, checking Vs is still the frist thing I'd do if I have sound, but no image in a plasma TV.
Next would be the sustain boards output...Leave a comment:
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Re: Sanyo DP50747-00 (Samsung Power Board LJ44-00132A) - Thought i had problem fixed
I will start with honestly saying I did not read the whole thread up to this point.
But today we've added LJ44-00132A and LJ44-00132B in the list of boards that we offer a repair service for and - when possible - an exchange program where you can buy a working board and then send yours back for credit.
This means we've repaired a few boards of each type and feel confident we can process a board within about 2 business days of receiving it; of coruse we can't always...Leave a comment:
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