Anothother LCD problem.. Viewsonic VP140

hmmm.. the shutting down appears to be unrelated to the inverter because if you power it up without the inverter it shuts down after a few seconds.. Just like it is doing with it plugged in..

I have fixed 3 or 4 of these before....but not for quite a while. It was always the same part and the same symptom. The display would shut down after 10sec-3 min. Removing power momentarily would make it work again.

It is due to a bad cap on a regulator (within the monitor; not the separate pwr supply) My memory is not great on this, so don't take my word on all the details.....but....

I believe is was on a 5 volt supply; maybe -5v. I think it was on the reverse side of the PC board; facing the LCD display. I believe it was a 1 ufd cap.

I am not sure why it is dim, but none of these ever look very good....I think the reflector gets tarnished (this is a guess!)

CV

Michael Kennedy wrote:

I'll change that cap out and see what happens.. Thanks for the info..

- Mike

Are you talking about an electrlytic capacitor because there are no electrlytics on the back of the board..

- Mike

It was a surface mount part...probably not electrolytic. I have one here that I fixed. I will take it apart to see the exact part....assuming I can see which part it was that I soldered. This may take a while. Cv

Michael Kennedy wrote:

Ok, this didn't take as long as I thought.

Keep in mind....I believe that they made at least 2 different versions of this monitor; so beware. Mine was made in Feb '99 with a serial number of AH90800764. The board number is 4141139001.

It looks like the part I replaced was an electrolytic (tantalum?) It is on the reverse side of the board. It appears I replaced it with a ceramic (non-electrolytic) cap. Since ceramic monoblock caps don't have labels, I can't tell the value; but based on it's physical size, I would guess either 0.1uf or 1.0 uf. Hopefully you can see the label on yours. It is C135. While this is a surface mount part, you can probably use anything that will fit.

As always, YMMV Good Luck cv

Caesar Valenti wrote:

Thanks... C135 is a 105 16v.. Is that 105uF?? pF? Sorry if that is a stupid question but I'm still trying to learn. If this is an electrlytic it is not one like I'm used to seeing.. It is a square yellow block that is about

I learn something new every day.

- Mike

That would be "10" followed by "5" zeros or 1000000pf or 1,000,000 pf or

1 million pf = 1 microfarad. I would go with a ceramic (non-electrolytic) if you can find one small enough. All the rest of mine are like yours....small yellow surface mount blocks....those are all caps. The really small black ones are resistors. Welcome to the world of miniature electronics!

CV

Michael Kennedy wrote: