One of our LCD TVs has no picture only sound - the picture is there but not lit so I presume this is the inverter board that's failed, or possibly the backlight.
It is a make I can find almost nothing about - Apro - and is a 20 inch Freeview model with a DVD player. Anyone know a source of possible spares or is this just not worth it? If it's a standard inverter part then maybe?
E.
Google for monitor inverter and fluoro backlight spares - there's a site which sells them quite cheaply. You might find a compatible part or one that can be used as it's near enough. I'm thinking a seperate inverter board of fluoro tubes that are near as damnit yours.
I've wondered what I'll do if my 32" turns up its fluoro toes or blows the inverter. I'll just buy a new one, but the old one would be stripped and repair attempted - perhaps putting the screen in front of a lightbox - as I did when making a diy projector panel.
Well if you cannot find out who makes it then you are in a bit of bother, as to have some idea on how to fix it you would need at least a service manual. I'd suggest its probably not going to be worth it unless you are very lucky and know a good womble.
Brian
Well I know the make and model - it's an apro AL-2010HDT - apro is lower case on the set. My wife can't remember where she bought it. Seems a shame to throw it out for something so fixable but this looks like a fly by night eastern manufacturer.
I suppose I can use it as a radio...
E.
Service manual isnt that relevant. What pimarily matters is length and diameter of CCFL, and the voltage the invertor runs on. What brand the spare is sold for isn't too important, but getting one that uses the same dimming system would be nice.
NT
I don't think I've seen a service manual for anything I've ever repaired.
Mostly, it's follow-your-nose, with occasional reverse-engineering of PCBs by drawing it out by hand.
Most faults don't require detailed knowledge of the innermost workings. Mostly, it's PSU and similar generic everyday electronic stuff.
If the fault required attaching a custom diagnostic do-hicky to a custom connector on the PCB, I'd not bother any further, unless it was determined that said custom thing was just an RS-232 port...
En el artículo , eastender escribió:
It'll almost certainly be a generic Chinese set with a bewildering variety of obscure brand names. Try a post to sci.electronics.reapir with a link to a good, clear photo of the inverter. Someone might recognise it.
If you're confident about disassembling the panel, you could see if the backlight tubes have blackened ends - if so, it's probably the tubes. Original spares will be impossible to get hold of but you may be able to bodge a pair of tubes from a scrapped set into place.
A very common failure mode...
I have fixed quite a number of LCD monitors with the same fault.
The chances are it will be one of four things. In decreasing order of likelihood: Loose connection, bad caps in the PSU / inverter, driver transformer for the backlight, or the CCL tubes themselves.
For a 20" screen there will almost certainly be more that one CCL. So the fact they are both off would suggest its not them.
So first job would be to check all the internal connections are well made where they plug into the PCB etc. Give em' a wiggle and try again. Next job would be to have a look for puffy electrolytic caps on the PSU PCB - that may also contain the LCD inverter circuitry as well, or it might be a separate board.
See:
Assuming all that looks good, then look at the inverter section a bit more closely. There will be a couple of pairs (probably) of wires that come back from the LCB backlight to the PSU/Inverter PCB. Close to where they plug in there will probably be a small PCB mounted transformer - it may not look like one - some are quite odd looking like:
(if fiddling with the output wires of the inverter when running, take care since they will have 600 - 800V on them!)
You may even find a separate laptop style inverter or two - but again the fact that both lamps are out would suggest not.
Thanks for your detailed reply John. I'll give it a good inspection.
E.
Just a belated note - I finally took the back off today (about 16 screws) and indeed the power connecter to the inverter board had worked itself loose.
It had done so because it was next to the main power input jack from the 12v power brick. This jack socket had become a bit wonky and I expect wiggling it about had dislodged the other connector. This is a pet hate of mine ? power inputs that are soldered to a main board, especially where the jack is often put in and out. I've seen it on a few devices, notably on my son's expensive Marshall guitar amp ? which obviouslty gets unplugged a lot - it failed completely and it is soldered to the main board, but I was able to get a local music shop to fix it. Very poor to have a component subject to mechanical stress as part of a circuit board.
And I expect 99 times out of a 100 a cheapish LCD TV would have been thrown out for such as simple fault.
E.
Sadly true... often worth grabbing them from those about to throw them out for just that reason!
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