DMGC

[EddyWouldGo]

Hiya,

I lurked for a while on BenHeck a couple of years ago with the intention of starting a portable project, but put my money into NeoGeo instead.

Now I'm going for a portable GC project but have a time limit as I'm off in the middle of November. There seems to be a few options for portable-building forums these days, but I've plumped for this ModRetro one - hoping I'll be able to gather a little help when I need it!

I'm not looking to break the mould here, or push any boundaries as I don't have the technical prowess, but hope to make something nice and tidy.

I've ordered most of the parts I'll need over this weekend, and just to take the piss within 10 minutes of buying a chinese 3.5" screen my Brother found one he was gifted after an eBay seller mistake!

It does mean I have a spare screen though, and can get on with a few more things straight away though. I am having a couple of issues already though!

For reference I'm in the U.K., using a PAL cube.

The screen worked perfectly first time I connected it, and showed good contrast and a clear picture. I only tested it for maybe 10 seconds.
I tried testing the second video input to see how it compared and it doesn't display properly (flicks on and off every second).

BUT! now when using the normal video input the picture's all washed out (too bright) and there's numbers counting (as if through channels) in the corner... I've tried many times over the last 24 hours and it's been consistently like this.

Can anyone help shed some light on these problems on 3.5" chinese eBay screens?

It looks like this: http://youtu.be/j0GTbragQUA

My screen is like #3 from Hailrazers screen overview, but the controller board is different (though I'm sure I've seen identical ones on here somewhere) - here's a pic:

I've tried running it from many voltages from 3v to 12v, and the results are the same except the screen becomes a bit brighter (it's still washed out from 3v though). I also tried another supply which goes up to 2.5 amps in case it was crazy thirsty, but no difference.

I've tried bridging some of the blank connections in the lower right corner of the picture to ground (while running) to see if they are unused and unmarked switches, but none of them do anything.

I've tested the GC signal an another screen (and it's good) and put a good SNES signal through it and all results are the same.

Any thought? Should I try a resistor in front of the video input?

Cheers,
Eddy.

 

[thecasperrojas]

i had this problem just one time and all i did was shorted the caps when it was turn off then turn it on agian and the problem was gone if need any help on how to short the caps let me now

 

[EddyWouldGo]

Hi, and thanks for your reply!

I've tried discharging the caps as you've suggested and it doesn't make any change.
There are three caps on the board, one held a volt and a half, another around ten, and the third none. After every power up the same amounts in each remain whether they are drained before or not.

I do have another screen on the way, so we'll see how that one fares...

De-ported my mobo this evening, had a scary moment when desoldering iron dribbled onto my mobo. It's in a blank area which will be trimmed off and it's only a few very small dots, but it certainly focused my attention.

Getting a bit nervous I won't find a Wiikey Fusion. Seem very difficult to find in the U.K. and not much easier in the rest of Europe...

If anyone has any info on ones whereabouts do please let me know!

Cheers,
Eddy.

 

[Tchay]

For starters, the "second video input" you used was S-Video I am assuming. No need to connect your composite line to the S-Video line of the screen controller board. But I don't think that would ruin your screen.

If you haven't already, try this: unplug the controller board ribbin cable from your LCD. Disconnect all voltage and ground from the controller board. Leave it like this for 5 minutes. Then try plugging it all back and and hook up to the composite video line.

Look back at your ebay listing. Find the item details and look at the voltage rating. Does it say DC5 or DC12 volts? It is possible that you fed in too much voltage and partially damaged the controller board of the LCD module.

BTW, I hate those screens. I like these better: http://www.ebay.com/itm/ws/eBayISAPI.dl ... 1150082284

^ just keep in mind it needs 12V. You might be able to get away with 7.4v but I haven't tested that yet. OH, and try not to unplug the ribbin cable from this LCD. If you do, you'll have to unplug the power from everything with ribbin cable unplugged, and wait a few minutes (like I mentioned above) otherwise your screen will just show up white. No idea why it does that, but its easy to avoid/fix.

 

[EddyWouldGo]

Thanks very much for your reply!

The second video input is another RCA jack. I put the same composite line into it. Does display the picture, but flashing as described. I assume composite signal wouldn't display through an S-video line at all as far as I'm aware they work quite differently.

I'll try unplugging the controller board from the LCD tonight, thanks for the idea!

The documentation for the screen says 12v, and it's also printed on the PCB of the controller board.
I haven't put any more than 12v through it yet, don't plan on it and don't know why anyone would?!?

After the problem started I tried using lower voltages and it works the same down to 3v. No difference in the problem, just slightly dimmer.

Thanks,
Eddy.

 

[EddyWouldGo]

Just had a look at the screen you linked Tchay - looks pretty sweet! (Was at work when I wrote the last post so didn't want to take the piss browsing too much.) The controller board looks a bit thicker than mine, but obviously it's way smaller in the other dimensions.

I tried your suggestion and it has made no difference. I had left it unplugged an hour, but no joy. Defo worth a shot - thanks for the suggestion. Will give it back to my Bro, maybe he can sort it himself...

I received the screen I bought today though, and it works perfectly. Same outer design, but with 3 buttons for simple control. Will open it up shortly...

This new one works down to just under 4.5v, (the old one craps out just below 3v!) which should align with my power plans okay...

Away for the weekend, so will be making regulators and trimming mobos next week...