Re: Toshiba 32W3451DB Backlight Problem
Sorry this has taken so long, but I should be returning this now operational TV to its owner tomorrow.
There have been considerable delays whilst I waited for particular components to be delivered and also a week ago I thought it was OK only for a another LED to fail and cause a new repair + long periods of soaking.
As previously stated I found the initial LED culprit. I replaced this with a 1W cool white LED - which was overbright and whilst trying/testing two more LED's on that same strip gave up working - suspect mechanical...
BBN
Member
Last Activity: 07-03-2015, 05:12 AM
Joined: 06-11-2015
Location: Dorset
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Re: Toshiba 32W3451DB Backlight Problem
Having removed the strips I was able to wok out the connection/tracking using a DVM and two sharp scalpels to penetrate white surface of PCB/strips.
Again using DVM but set to diode test where a voltage reading is expected I was able to test each individual LED - one way round about 0.2V other no reading but very dim pinpoint of light on led connected. One LED @ one end of a strip gave no reading and no light and viewing this more carefully I think you can see a burn mark underneath it! (see attached).
I bypassed...Leave a comment:
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Re: Toshiba 32W3451DB Backlight Problem
These are brief photos of the backlight strips
2 strips each with 11 leds approx. 575mm in length. and 12mm wide
Green PCB joining these is 17DB01.
Each LED strip has written upon it horizontally @ left hand end VESTEL 32 inch REV0.2 TIS-4A 94V-01346
Each LED strip has written upon it vertically @ right hand end LJ AHB2 1003 VES315 WNDL-01....Leave a comment:
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Re: Toshiba 32W3451DB Backlight Problem
As you may expect, looks as Zener diode blown S/C.Leave a comment:
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Re: Toshiba 32W3451DB Backlight Problem
Some progress - still awaiting replacement PSU. After recent comments and looking elsewhere however - my thoughts were 'if it is a shorted LED - how can I perhaps simulate things?'
Placed a 3V9 Zener in series with the backlights and retried. Still no obvious 'lights' but now the LED backlighting drive voltage has looked to stabilize - Now RED lead closer to +72V and black line not obviously fluctuating - @ approx. 1.5V
Looks like the load the LED backlighting was placing on the drive was such that it somehow...Leave a comment:
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Re: Toshiba 32W3451DB Backlight Problem
This is my initial guess - although I do intend to try a replacement PSU PCB 1st - have been waiting for delivery, hopefully sometime this week.
If it does turn out to be the LED's how do I replace them as I cannot find any real indication of how to take apart the panel bit? I was told by another party that there was detail on 'forums' for this - but I have not seen anything yet?Leave a comment:
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Re: Toshiba 32W3451DB Backlight Problem
If you look @ earlier message that is already there:
At present - there are two connections to the LED(s) and a DVM across this pair indicates something odd - may be pulsed DC of some form.
Red wire LED to chassis approx. +27V DC. Black Wire LED to chassis/0V approx. 1.5/2.5V DC - but again suggests pulsed or something.Leave a comment:
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Re: Toshiba 32W3451DB Backlight Problem
No sure whether this is what you want - but basic overview...Leave a comment:
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Re: Toshiba 32W3451DB Backlight Problem
If I knew what voltage to actually expect I would be measuring it.
At present - there are two connections to the LED(s) and a DVM across this pair indicates something odd - may be pulsed DC of some form.
Red wire LED to chassis approx. +27V DC. Black Wire LED to chassis/0V approx. 1.5/2.5V DC - but again suggests pulsed or something.
Can I drive the LED's with something else to test them? If so what?Leave a comment:
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Toshiba 32W3451DB Backlight Problem
I have a Toshiba 32W3451DL LED backlit TV - panel VES315WNDL-0 with no backlight - fails torch test but all signals etc OK. Actual LED strip(s) [??] not visible as within panel - not sure if PSU (which I assume includes LED driver) or actual LED's - how can I test/determine which and can anybody point me in the correct direction on to how to dismantle the panel gaining access to the LED's please? -
Re: New Members - please post your introductions here
I guess I had better introduce myself.
60 year old Electronic Design Engineer from the UK - but TV is not my scene.
I am stuck now trying to sort out my 'offsprings' TV problemsLeave a comment:
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