WTD: Schematic for power supply of LG L194WT-SF Monitor

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Hi all,
I'm looking for a schematic of the switching power supply of an LG L194WT-SF
monitor. The monitor part works fine,  but the power supply continually
shutsdown when a load is applied to the 5V rail.
The SMPS IC I think is an FAN7601 but the IC labelling identifies itself as
an LAF0001 (which I've not heard of, potentiall an LG stock number?)

I'm going through the junk box for resistors of various values to use as a
load. With 4.4 Ohm ( which is about what it will see) it shutsdown, with 75
ohm it looks OK.

LG state that they do not release schematics or service manuals for their
monitors. I'm sure someone must have a schematic for the SMPS ? I'd rather
not reverse engineer a schematic. The power supply board has a part number
of EAX351599301/7

Thanks
Greg



Re: WTD: Schematic for power supply of LG L194WT-SF Monitor
On Thu, 17 Mar 2011 17:24:19 +1100, "gcd"
and composed:

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Do these help?
http://elektrotanya.com/lg_l194wt-s.pdf/download.html
http://elektrotanya.com/lg_l194wt-sbfq_e.pdf/download.html
http://elektrotanya.com/lg_l194wt_lm57g_chassis.djvu/download.html

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Re: WTD: Schematic for power supply of LG L194WT-SF Monitor
On Mon, 21 Mar 2011 08:06:52 +1100, Franc Zabkar

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... or these?
http://www.jordansmanuals.com/default.aspx?Brand=LG&Product=Monitor
http://www.jordansmanuals.com/Default.aspx?Brand=LG&Product=Monitor&Model=L194WT

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Re: WTD: Schematic for power supply of LG L194WT-SF Monitor
Hi Franc,
no, no help. I've looked at those, they have the schematics for the lcd
controller etc but not the power supply. They call it a LIPS and leave it at
that. They have a parts list for the PSU (LIPS), that where I got the
FAN7601 from. The parts list doesn't quite agree with what I see on the
board but the controller pinout looks correct.

Thanks anyway
Greg


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http://www.jordansmanuals.com/Default.aspx?Brand=LG&Product=Monitor&Model=L194WT
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Re: WTD: Schematic for power supply of LG L194WT-SF Monitor
On Mon, 21 Mar 2011 10:47:00 +1100, "gcd"
and composed:

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FWIW, here is an application note and circuit for the FAN7601:
http://www.fairchildsemi.com/an/AN/AN-4129.pdf

This thread looks interesting:
http://microsin.ru/content/view/1223/43 /
http://translate.google.com/translate?hl=en&sl=ru&u=http://microsin.ru/content/view/1223/43/&ei=x7mHTY75BoiecY-O9aAD&sa=X&oi=translate&ct=result&resnum=5&ved0C%DgQ7gEwBA&prev=/search%3Fq%3DFAN7601%2BLAF0001%26num%3D25%26hl%3Den%26newwindow%3D1%26safe%3Doff%26client%3Dopera%26hs%3DeY7%26rls%3Den%26prmd%3Divns

It suggests that there may be a circuit diagram in the service manual
for L1717S, L1718S, L1719S, L1919S, L1730, L1752TQ, L1952TQ.

It would also appear that FAN7601 and LAF0001 may be equivalent.
According to usbid.com, both are manufactured by Fairchild.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Re: WTD: Schematic for power supply of LG L194WT-SF Monitor
Hi Franc,
thanks for the information. I'll have a read. The only info I could find on the
LAF0001 was for an adsl splitter or similar.

I've seen the app note too. This psu reflects a little of the app note but not
all, but it was helpfull to do some checking. It
looks as though the chip is turning off as VCC increases with load. A load on
the 5V rail trip this circuit and a load on the
12V does not.

The russian site you link to has a message describing the same failure mode.
However the repair, replacement of a 1000uF cap on
the 5V rail, didn't work for me. That was the 1st thing I did, replace the caps.

Also, further research on ebay shows a replacement power supply from China for
about $25 delivered, so I think that may be
worth considering too.

Appreciate the detailed help and I'll read the russian site a little more and
check the service manual for the 1717. I've also
bought a FAN7601 replacement incase the one on the board has a faulty overload
detect.

The file has finished downloading and the L1752TQ manual seems to have the right
schematic !!

Cheers
Greg


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http://translate.google.com/translate?hl=en&sl=ru&u=http://microsin.ru/content/view/1223/43/&ei=x7mHTY75BoiecY-O9aAD&sa=X&oi=translate&ct=result&resnum=5&ved0C%DgQ7gEwBA&prev=/search%3Fq%3DFAN7601%2BLAF0001%26num%3D25%26hl%3Den%26newwindow%3D1%26safe%3Doff%26client%3Dopera%26hs%3DeY7%26rls%3Den%26prmd%3Divns
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