Would bad caps cause this display?

[lurker]

Got this Dell 2405FWP monitor with this (video noise?) lines/dots on the display without a video cable plugged in. I was wondering if bad caps would cause this? Has anyone an idea what would cause this behavior?

Thanks in advance.

A little about me. I've have had limited success in repairing electronics. Fixed a couple of active subwoofers with blown caps. One of the sub's cap was completely gone when I opened it, just the two soldered wires remained. Had some luck changing caps and ccfls in monitors. Reflowed bad solder joints in AV receivers. I basically try to get stuff free or buy it for cheap with the hopes of fixing it. Some of these purchases are starting to crowd out the garage (irritates the wife giving me more initiative to find more stuff to fix).

[Lumberjack777]

Re: Would bad caps cause this display?

That looks like it might be the T-Con board. I know what it looks like with a signal coming from the VGA or DVI video input. Can you plug that in (to get a picture on the screen) and take a few more pictures? I'm about 90% sure this is T-Con board. Last I saw China was unloading that T-Con board for about $35 each new.

Also, can you update your profile with location and all? That helps us determine things like voltages, etc.

[lurker]

Re: Would bad caps cause this display?

Got a few more pictures here. I'm so used to these PHD cameras (push here dummy) that I don't know how take darker images. Let me know if I'm compressing them too much.

So Lumberjack, seen any "flying fish" lately?

I looked at the T-Con board you had mentioned. Looks like it's buried under some radiation shield and had two ribbon cables and two plugs going into it. Makes sense that would be the number one suspect.

Thanks for your help.

[Lumberjack777]

Re: Would bad caps cause this display?

So Lumberjack, seen any "flying fish" lately?

Hahahahaha. Clever

Those pictures are fine. Still looks like T-Con to me. But I suppose it could be something else.

Try cleaning and reseating all those ribbon cables. But I doubt it will help.

If anybody wants to chime in and maybe give him some diagnostic tests. Feel free. I'm not sure how you test a T-Con board.
Or if it definitely looks like T-Con board to you also. Looking for a 2nd or 3rd opinion here.

[lurker]

Re: Would bad caps cause this display?

Removed the radiation shield to expose the board. Maybe I can try some freeze spray or heat to see if that changes the display.
There's 11 bigger caps on the main board that appears to be okay. I suppose I can try swapping some out. I tried checking one of the caps using and old analog multimeter (Triplett 630-A) using this method:

http://electricaltechnology.org/2013/06/how-to-check-capacitor-with-digital.html

According to the instruction on that page the cap s/b okay.

I tried to move to the city of the "flying fish" but it didn't work out so here I am pecking away at this keyboard instead of sipping a hot one from the original Starbuck's and ducking at the yell of "incoming".
Thanks.

[SteveNielsen]

Re: Would bad caps cause this display?

That test won't tell you if the cap is ok. It doesn't tell you anything except the cap appears to charge with a low DC voltage applied and that it isn't shorted, nothing about its capacitance, esr or anything else.

I almost choked reading his Method 1. That's about the stupidest advice I've ever read.

[lurker]

Re: Would bad caps cause this display?

I surprised by the reply, I figured that there was no one out there, except for Lumberjack, with a suggestion. Looking back, that was the only suggestion so far. After reading around the net seems like Lumberjack is right, the bad picture points to the T-Con board.

As far as checking caps, using a multimeter is the was the only way I found without having an ESR meter. If anyone out there knows another method, please let me know. I really don't plan on buying a meter anytime soon, I will just continue using what ever I have on hand and in this case it's my 60 year old Triplett meter.

Charging caps, especially big caps scares the craaaap out of me. I've seem them used to clear voltage leakage between isolators. That's why I skipped pass Method 1 on the page.

Thanks anyway.

[lurker]

Re: Would bad caps cause this display?

Lumberjack - you were right, it was the T-CON board. Bought one for 25 bucks, including shipping, installed it and no more lines. This is a nice high resolution monitor.

Thanks.

[Lumberjack777]

Re: Would bad caps cause this display?

Nice job! Thanks for the feedback.

[blargg]

Re: Would bad caps cause this display?

Yes, feedback is an important part of the repair process, so everyone else (perhaps yourself in a few years) knows what problem these symptoms were a result of.