LP2407 No Display

[wagb278]

I have a Gateway model FPD2485W (LP2407) LCD monitor that has failed and I would like some help to determine if I can fix it.

My sympton is nothing appear on the display screen. The power button and menu buttons light up and I get the audio tone when power is applied. When this was working - when power was applied I would get a Gateway logo on the display but that no longer happens. Also, not surprisingly, there is no display of DVI or VGA notice at power up. Another (less important) problem I have is the USB ports don't work, but that started over a year ago. I presume the USB port problem is unrelated to the display not working - which just happened this week. Working USB would be nice, but is less important to me.

I have taken the beast apart to perform a visual inspection. No burn marks or other real obvious indications; but I am not an electronics tech, so what do I know about such things - NOTHING! It looks to me like I might have some "buldging" capacitors on all three (less the USB board) but the difference is rather subtile to my untrained eyes.

I have read with interest a few posts on this forum that people in my situation were able to fix their monitors - so what the heck, I am willing to try. I uploaded some photo files. Hope I uploaded them correctly and they help someone to suggest what I should do.

I have a digital multi meter, and a soldering iron and I am not afraid to try replacing capicitors, although I have never done this before. The monitor is either going to get trashed or fixed.

I discovered a site (LCD Alternatives) that sells capacitor kits for this monitor's boards. Does any one have experience with that vendor? That site had a video on how to replace caps.

Oh - assuming I replace components, can I try powering this up with our putting the back on just to test it? Getting that off was a pain and I would not want to do that multiple times.

What should I try first?

Thanks,
Jim

[(*steve*)]

Re: LP2407 No Display

Yep, you have a good set of bulgy caps there.

The ones on the inverter board seem to have vented a little electrolute out of the tops.

The doming on the top surface may be slight, but *anything* is a sign of damage.

At the very least, I'd be replacing all the ones that have domed tops, and any similar ones nearby. (i.e. if there are 3 in a row and only 1 is obviously damaged, replace all three).

Replacing all the electrolytic capacitors may be going too far, but unless you know which ones are bad...

The only exception is the large 400V capacitor. In most power supplies these are not hugely stressed, although there are notable exceptions.

[wagb278]

Re: LP2407 No Display

Thanks Steve, I will order caps. The physical difference in appearence is so slight I wasn't sure that indicated a problem. It seems I have bad caps on three boards. I will report back after I replace those that seem bad.

Jim

[(*steve*)]

Re: LP2407 No Display

Consider the cost of replacing other caps too. You may find that with shipping it doesn't add a lot more to get a full set.

Make sure you get low-ESR capacitors where appropriate. If the exact capacitance and/or voltage is not available it is OK to go 20% to 50% higher in capacitance and higher in voltage. As you increase either the size increases, so if you go too far, they won't fit.

It is also advisable to try to locate specs on the original capacitors (OK, that may be hard) so you can determine the ripple current rating. Finding replacement capacitors with a higher ripple current rating is great because when it really comes down to it, it's the ripple current which is most likely causing the damage to these capacitors.

Good supplier, "good" brand name caps are also well advised.

I understand the guy running this forum supplies caps. I would suggest that whatever he supplies should be pretty good or he would lose his reputation.

[wagb278]

Re: LP2407 No Display

I ordered and received the capacitor sets.

I finally had some time to replace the capacitors and that did not change any of my symptoms. The monitor will not display anything, but on power-up I get the welcome audible tone and side panel buttons light up Blue (normal).

I only replaced the capacitors that showed signs of bulging. The rest looked pristine.

I had to button up the monitor (couldn't leave it out with visitors coming). I doubt I will persue this further, it was a good try. I found it difficult due to my poor eyesight. and I don't look forward to trying to take te back off again.

But this site is great with tons on good information.

Thanks for the help and advice.
Jim

[addytzu123]

Re: LP2407 No Display

Hi, beside the bulged E-caps on inverter, have you checked also the small SMD fuse located near them? If that is good on measuremet, than things get more complicated (SMD mosfets shorted), but you can still search the web for an inverter board QLI-002.

[kc8adu]

Re: LP2407 No Display

anyone know the part numbers on the 4 mosfets are?
q1 q2 q3 q4

[selldoor]

Re: LP2407 No Display

Are they labelled etc Q1 on your board , other components seem to be *8**

[kc8adu]

Re: LP2407 No Display

yes they are labeled nearby.originals are powder.