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From: Graham Robinson on 26 May 2007 03:01
Hi Dave, i've been repairing a few TFT monitors lately and i agree with
James that service information on these units is very difficult to come
across, You can spend hours Googling schematic sites to no avail.

What i have found though is that these inverters seem to be very sensitive
to imbalance between the performance of the TFT tubes. As the Inverters are
usually feeding a pair of tubes (sometimes 2 pairs) a failing tube seems to
cause an imbalance in the current drawn and the inverter chip will shut
itself down.

I keep a set of known good tubes and plug these in to the inverter,
invariably these will remain lit indicating that the Inverter itself is ok
and the fault is in a failing tube. If it is the Inverter thats at fault
then, assuming you have a good drive signal from the inverter drive chip you
should turn your attention to the main output transistors and transformers,
look for blackened or burnt windings on the transformers as they do go s/c
with alarming regularity.

Good luck

Graham




<jamessweet(a)hotmail.com> wrote in message
news:x8PVh.10268$uF1.3210(a)trndny04...
> Dave Dunfield wrote:
>> Looking for schematic or other technical information
>> on an LCD power-supply./inverter made by IPT
>> (www.ipt.co.kr)
>>
>> Model is IPHS4L19 REV 1.2
>> 03KJUL11225
>>
>> This is from a Hansol/Multitech H950 monitor.
>>
>> Power supply portion appears OK, however when
>> the inverter is activated, the backlights only flash
>> briefly (By strobing the backlight control I can see
>> that the image is being displayed). Looks like it's
>> not oscillating at all after power-on, or is shutting
>> down very quickly.
>>
>> Dave
>>
>
>
> Schematics for this sort of thing are not available, they're considered
> replace-only devices. You're on your own I'm afraid, fortunately they're
> not very complex and can usually be repaired.
>
> Sometimes a bad tube will be detected and the unit will behave in that
> manner as well.


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