Bad screen, or bad pcb? (w/ video)

Hi all. I'm hoping one of you has run into a similar problem as me, so that I don't spend too much time chasing down a bad solution.

Basically, my 4000 (bought used over ebay) was working fine for a few months when suddenly I get this on startup:

http://youtu.be/oZ2Y9b8ra7A

As you can see, the splash screen pops up for a second or two, then gets garbled up as everything continues to load.

Can anyone tell if it's a bad lcd screen or a bad pcb?

The reason that I think it's a bad pcb is that the splash screen stays around longer (on the order of a second or two) after unplugging for a bit. This leads me to believe that perhaps a capacitor has gone bad on the related pcb. But I guess I still shouldn't rule out a bad logic controller on the LCD board or something.

Anyway, any insight you guys could provide would be appreciated.

In the meantime, I think I will try recapping the power supply and the PCB since that will be much cheaper right now than replacing the screen and/or the PCB outright.

A shame that I finally have time to really dig into the 4000, and this sh*t happens.

I saw this once when I was working at AKAI years ago. I personally didn't fix the problem, someone else did. If I remember correctly, there is a bad solder joint on one of the boards.

Be sure the ribbon cable that connects to the screen the main board, isn't unsecured, apart from that. I feel your pain!

Thanks adrian - I'll be sure to check the solder joints, and probably will try giving them a once over them with my iron.

Reveal - thanks for the sympathy man! I checked the ribbon cable, and it still does it with the ribbon firmly seated. So now I have the whole thing completely disassembled to see if I can lock down the cause of this. I'll try recapping the power supply first, then move on to the other boards if that doesn't work.

I'm pretty determined to figure this thing out -- I've already looked at the service manual to figure out the signal paths for the LCD signals, and will be concentrating my recapping efforts there. But considering that I have the whole thing in pieces now, I'll probably just recap everything if the price is right.

I'll update with anything I find.

Hope you get it sorted.

Check the ribbon cable at the screen enclosure end. It can come out of the actual lcd unit too. It is easy to have the lcd enclosure apart. I didn't see your video but I have had problems with the screen twice and found the ribbon cable to be the culprit on both occasions.

Wassup yall...just wanted to resurrect this post to provide an update since I've finally gotten around to the recapping job...

Opened up the 4000 and replaced some of the caps on the mainboard. Desoldering some of the caps was a little tricky in that since the holes are tiny, the old solder wouldn't clear completely. So when soldering in the new caps, I'd have to reflow some of the old solder on each side and basically "rock" them back in. If anyone ever takes on something like this, you'll see what I mean. I replaced the groups of caps at the bottom portion of the board. I was planning on replacing all of the caps on the board, but a combination of not having enough time and laziness happened.

I also cleaned up some liquid residue that was on the boards, which appeared to be soda or coffee from the previous owner(s). Some of the residue was around some of the IC pins. Since the residue has been dried up for so long and the 4000 did work for some time, it probably wasn't the cause of any shorts or the issue as shown in the video, but why take any chances with a dirty board. Some isopropyl alcohol and q-tips cleaned it right up.

The result? Now my 4000 boots up properly with the display screen looking sharp! Maybe it's just me being overenthusiastic about the fix, but I think the display looks better than when I first got it. I do get a momentary line on the screen, which disappears after a couple seconds, but I'm thinking that means the LCD unit is showing its age.

If anyone wants, I have a list of the caps and values I bought as well as a diagram of where each cap value goes that I'd be happy to share -- it'll save you some time, which you'll need because recapping can be a **** with such small through holes.

Take your time, check your work afterwards, and you can fix this for around $30 (for the caps) and some elbow grease.

Hi Pauze,

my 4000 has started showing lines across the screen, I'm hoping I can fix this by doing what you described, would you be able to give us a list of the caps/values and diagram, I'll have to find someone who is an ace @ soldering.

Many thanks in advance.

Jamez aka Kutz