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DARKSOFT LCD troubleshooting / repairs

Hello! I've got a bit of an issue with my LCD.

While removing the connector to prepare it for installation in a Jasen's CPS2 case it seems one of the pins brought along their parts-side pad (the middle pin closest to the board edge, see photo).

The LCD now only produces solid blocks as shown in the image, and the system outputs a green screen. :unsure:

I was hoping I might be able to do a simple bodge job on this, and was seeking to know where the indicated parts-side pad goes (to effect the repair)?
 

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Thanks! I was able to use the image to pop on a quick bodge wire!

Having said that, it seems to have had little- if any- impact. The screen still exhibits weirdness. Unfortunately, I haven't a clue as to what the issue is at this point. Like before, the LCD displays blocks and the unit boots to green screen.

?(

Any advice I as to where to look next?
 

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dillingerradio said:
Thanks! I was able to use the image to pop on a quick bodge wire!

Having said that, it seems to have had little- if any- impact. The screen still exhibits weirdness. Unfortunately, I haven't a clue as to what the issue is at this point. Like before, the LCD displays blocks and the unit boots to green screen.

?(

Any advice I as to where to look next?
Click to expand...
If it is indeed the display you can replace it with another 1602 lcd. They’re pretty cheap on Amazon. If you go back a few pages I also have a 1602 OLED from AliExpress that works.
 
Unfortunately, I'm unaware if it's the LCD specifically. Manipulating the buttons to try and flash a game in the background did not yield any LED activity on the board, indicating both the screen and controls are dysfunctional. I don't have enough knowledge to understand the issue.

I ordered a new LCD module of the same standard from eBay and will test that (since they're cheap, anyways).

Since it may be relevant, I want to reiterate that this LCD (and module as a whole) functioned fine prior to me removing the connector (as previously mentioned). I did notice I seem to have tapped the trapezoid on the side of the LCD with the desoldering gun while I was working. I've uploaded a photo; the mark on left is rosin flux residue from my fingers; but the mark to the center-right is heat damage from the incident. Surely that couldn't have done it in, though? The damage looks minor, but inexperience keeps me from feeling confident.
 

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Hello again!

I'm following up - it seems the LCD is not the root issue.

To start, let me reiterate the work done so far:
- Multi installed.
- Multi tested to verify functionality.
- LCD removed
- LCD connector removed to support installation of 90 degree joint
- LCD reconnected
- Unit fails to boot, LCD appears dysfunctional (two solid rows of blocks).

With that in mind, I ordered a new LCD unit. It arrived today. I installed the new LCD unit which is the same as the one that was removed as far as I can tell.

After powering on, I observed the top row was white blocks (the bottom row was nothing).

I then attempted to adjust the contrast using the knob on the multi-board, it was shortly after this that the unit began emitting white smoke from the location of the contrast pot, and I immediately shut down power (supplied by a known good RT-85A running 5V at the edge verified).

I don't know what to do at this point. The only thing I've changed is swapping out the connector and that's fairly simple work. I don't know what's causing the main unit to emit smoke and I didn't see anything visibly go up. The contrast pot appeared to emit white smoke a second or so after I manipulated its position.
 
Is the orientation of the connector and cable right? Sounds like power went somewhere it shouldn’t. Smoke isn’t a good sign. Perhaps check with other people who have done that mod for the case?
 
:|

I don't know how I didn't realize my orientation on that was going to be wrong no matter what. Thank you for pointing that out. I feel very silly, but it happens. In any event, popping the pins back over to the front side has- in fact- resolved the issue. I tested a few games at random, and they loaded appropriately and responded as expected to input! The white smoke was alarming, but I'm going to assume- for now- that I managed to power down before anything bad could kick off (since everything appears to be working).

A big thank you to @djsheep for helping me see the problem right in front of me.
 
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Luckily for you the multi has several security measures in place to avoid a shortcut frying the whole pcb. Looks like you were lucky as well and noticed that quick. Enjoy.
 
Indeed! And now we know they're at least robust enough to resist a dummy who flopped a connector around without considering the orientation of the ribbon cable in his head. :D

Thanks to everyone who chipped in to help, I appreciate all the helpful comments and troubleshooting.
 
djsheep said:
On @TodoRojo pic the connector is soldered to the top of the board (parts side) On your photos it looks like you’ve soldered to the underside (solder side). That would be the issue I reckon… hopefully no permanent damage has been done to the multi or your donor.

1742021592290.jpeg
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Good catch, I can’t believe I didn’t notice that! Glad it’s working @dillingerradio
 
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