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

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

Reply to
gcd
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On Thu, 17 Mar 2011 17:24:19 +1100, "gcd" put finger to keyboard and composed:

Do these help?

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- Franc Zabkar

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Reply to
Franc Zabkar

On Mon, 21 Mar 2011 08:06:52 +1100, Franc Zabkar put finger to keyboard and composed:

... or these?

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- Franc Zabkar

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Reply to
Franc Zabkar

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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Reply to
gcd

On Mon, 21 Mar 2011 10:47:00 +1100, "gcd" put finger to keyboard and composed:

FWIW, here is an application note and circuit for the FAN7601:

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This thread looks interesting:

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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

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Reply to
Franc Zabkar

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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gcd

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