I bought a bunch of soldering stuff this week and yesterday I decided to take a whack at the ol’ Graphic Bypass Surgery that DanB managed to pull off a few years back. I’ve found that the operation isn’t so much difficult, exactly, but in fact is just barely possible from a physics standpoint. The fact DanB found a way to make it work with a soldering iron and without cheating is quite noteworthy.
In a quest to find a better way, I decided to see if I could pry the connector slot open and see if that had any better soldering points inside. It’s a solid piece of plastic, and it does give a lot more solderable surface area, so that’s something one might consider if you can find a way to crack it open cleanly. Me, I wasn’t so careful with it and lifted a few pins off of the mainboard, so I decided to yank off the entire slot… for science!
Removing the ribbon connector slot opens up two handy opportunities for soldering: 1) it gives you a nice flat surface to clip to instead of trying to go down over the back of the slot, and 2) it exposes several vias, and there happens to be one of those for every pin on the slot. This second opportunity is especially helpful because it provides a way to solder to the main board in a way that will keep the wires isolated from each other.
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Main Board Vias
Attached to this post are three labeled photographs of the display vias on the main board. The left-most pin on the slot is labeled as #1 on the board, and the right-most slot is #30. I used the same numbering scheme in my images. Please note that all of the numbers are intentionally overlapping the actual vias in the photographs, so don’t get confused when a number is near one of the holes. The number will always be on the hole it corresponds with.
Pins 11, 15, 16, 18, 23, 25, 27, 28 and 29 are connected to each other on both displays. I don’t know exactly why this is, but you can see them running under the cartridge connector and I verified their positions with a multimeter. The left display appears to be the “primary” display, and the right display is the other one. Several vias on the left side of the main board are used for connecting the corresponding pins on the right side.
The via for pin 1 on the left side is filled with solder, so you won’t be able to pass a wire through it very easily. Pin 2’s via on the left display is partially covered by the cartridge connector and should probably be accessed from the reverse side. The “on the left side but connecting to the right side” vias for pins 25 and 28 are completely covered by the cartridge connector, so they’ll either need to be accessed from the reverse side or the left-side vias used to connect both wires.
In the photos, yellow numbers represent vias for the display on the same side, while cyan numbers represent vias or pins that connect to the display on the other side of the board. The two red numbers are blocked by the cartridge connector.
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Stranded Wire Woes
I could use some help from someone more experienced with this problem…
You can find 30awg silicone-coated stranded wire nowadays, which is pretty much the best wire for this job. You don’t want to use solid-core because that will break after repeated uses of the IPD knob and you’ll be back where you started.
The problem I’m encountering is that the wire strands spread apart when I place the soldering iron on them to heat them up. This is fine for the vias on the main board, but the only real way to solder to the display board is to use the surface contacts, where spreading strands apart will cause some rather unwanted shorts. I need to keep them clumped up while they heat up, and I can’t find any literature on that.
If anyone knows a way to get around this problem, please let me know. Otherwise, I’ll look into doing what DanB did and scratch off the green coating around the vias on the display board in order to produce a solderable spot that way.
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