My backlights arrived from China yesterday so will be fitting them tomorrow. Is definitely the backlights, they are blue.
Cowdenbeath eh? I was born in Lo'gelly
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shandybass
Member
Last Activity: 04-09-2025, 04:15 PM
Joined: 11-09-2018
Location: Nuneaton
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Re: Lg49uh620v
My backlights arrived from China yesterday so will be fitting them tomorrow. Is definitely the backlights, they are blue.
Cowdenbeath eh? I was born in Lo'gelly...
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Re: Lg49uh620v
Thank you lotas. I completely missed that info on the board. I have just checked the board from the video I watched and it is marked 264v so seemingly this board may be supplying a near enough correct supply voltage.
Seems there is very little choice other than to remove the panel and take a look at the backlights.
Thanks again....Leave a comment:
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Re: Lg49uh620v
Got a feeling this is one of the rare cases then. I watched a video of a guy diagnosing then changing the backlights on an LG 40LF320v. He measured between A and B and read 250v dc which he stated was a good supply voltage for the backlights.
If I measure this bigger set between those 2 points I read a PD of only 98v. If I measure A, the midpoint and B with respect to chassis I get 64v, 113v and 165v respectively.
I'm just hoping that someone can confirm that these voltages are indeed too low before I order a replacement....Leave a comment:
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Re: Lg49uh620v
They were the 1st things I tried mate. There is definitely a fault on this set. I am just trying to ascertain whether the fault lies with the power board or if there may be a faulty led or 2.
I don't relish removing the panel needlessly.Leave a comment:
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Lg49uh620v
This tv belongs to a friend who was gifting it to an elderly lady. She complained that it wasn't bright enough for her deteriorating eyesight.
Sure enough it was dimmish with the backlight, contrast and brightness all set to maximum.
Choosing vivid mode helped slightly but obviously there is a problem. I'm an old engineer more used to crt screens than led. Retired now but would like a play with this set.
I'm struggling to decide whether the fault lies with the backlights or the power supply.
I have no schematic for the board which is a EAX66923201 1.4... -
Re: Compaq Presario V4000
I've found it.
Was sitting underneath the PCMCIA slot.
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Compaq Presario V4000
Not sure if a boardview is available for this relic of a laptop but if it is I would really appreciate it.
Belongs to my neighbour who only really wanted me to retrieve photos from the old style ide hard drive but I would prefer to have a crack at the repair whilst it's here.
All voltages I've tested so far are there for a short period. Power switch lights amber for a few seconds before extinguishing and voltages disappear. Battery charge indicator led will then flash every 30 seconds or so. Input voltage is there constant as is DCBATOUT and the 3.3 and 5v always.
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Re: Asus X450CC
This is how every amateur wastes so much time trying to find a fault. The laptop is dead so the beginning is where the dc enters the board. Readings from there will soon pinpoint the fault area.
Why waste time taking zero readings from "every big grey coil on board for voltage and resistance to ground" when the board is "dead"
The mind boggles
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Re: Acer Aspire 5742ZG working on battery only!
Well done Frenk7
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Re: Compal LA-8127P no power (help please)
Explain???...Leave a comment:
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Re: Acer Aspire 5742ZG working on battery only!
Is it the original adapter and have you got another one you could try? Just wondering if you are perhaps getting excessive ripple.
Did you have any problems identifying PR296 when you replaced it? Your boardview appears to be a mirror image of your actual board.Leave a comment:
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Re: Compal LA-8127P no power (help please)
Unconnected pins do seem the likely problem. Pin 5 ACOK could be a complete red herring and rather than being pulled low is simply not making contact.
All conditions "appear" to being met for REGN but as piernov points out it really only suggests the soldering or the new chips aren't good.
As a test you could try shorting ACDET to gnd and see if ACOK goes high. Umm, just thought that won't work as NO REGNLast edited by shandybass; 02-13-2019, 11:20 AM.Leave a comment:
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Re: Acer Aspire 5742ZG working on battery only!
You're barking up the wrong tree Frenk7. According to post #28 your problem is only present when both the charger and battery are connected or charger alone. If everything is fine with only the battery connected then all circuitry after ac/dc switching is ok.
It appears you still have a power problem.
My OpenBoardView won't open your board file for some reason which would make life a little easier but I'll take a look at the circuit again shortly and see if I can help at all.Leave a comment:
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Re: Acer Aspire 5742ZG working on battery only!
PR296 which is connected to pin 1 of PU18A ?
I'm surprised that it going to 80k alone would account for such a low on pin 1 though. What voltage do you have there now?
Would help also if you could take and post hi-res pictures of the board where the liquid damage has occurred.Leave a comment:
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Re: Acer Aspire 5742ZG working on battery only!
The gates of PQ51/52 aren't being driven low because the gates of PQ59 and PQ63 aren't being driven high.
This is due to pin 1 of PU18A being low @ 0.03v. This pin should be around 4.3v as pin 3 is greater than pin 2.
I'm a bit long in the tooth now so maybe my theory isn't right but I would be checking for a s/c PD1 or replacing PU18.Leave a comment:
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Re: Acer Aspire 5742ZG working on battery only!
Check for VS rail voltage, pin 1 of PC213. If ok then check voltages on PU18ALast edited by shandybass; 02-11-2019, 03:41 AM.Leave a comment:
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Re: plz I need help
That is the schematic I have posted mate and according to it pin 7 is not connectedLeave a comment:
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Re: plz I need help
Here's the circuit mate, not the best quality I'm afraid. Pin 7 has no connection but I don't really understand your question either....Leave a comment:
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Re: A1286, 820-2330-A board view
Since you asked so nicely
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Re: Dell XPS 12 schematics needed
Try this mate...Leave a comment:
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