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[jhelmuth]

Step 5 – Modifying the Sync/Green/Red/Blue signal traces



[1] We’ll start by doing the most difficult one first (the Sync signal trace located under the display).


a) Flip the assembly over onto its face (put down a nice static free mat or a static fee plush cotton hand towel to avoid any potential damage to the display).

b) Remove the 4 phillips head screws that mount the display screen to the circuit board. There is also an additional solder mount that must be un-soldered (near screw mount #4) to remove the screen. You can probably get away with just heating it up and wriggling it out, but I used some solder wick (recommended – see pix of tools) to make it clean and easy for re-assembly.

c) A flat mylar ribbon interface “cable” remains attached to the display screen AND the circuit board. This may be removable, but I did not attempt to do so as it was not necessary and I observed that the connector had some sort of white compound that may be a “glue” (or at least an anti-tamper material). Removing it looked as if it would make the job easier, but to avoid any potential damage I opted to not attempt removal.

d) Simply sliding it above the area where the sync trace is located (see red box in the pix) will expose it sufficiently to allow the necessary work.

e) Taking your box-knife cutter, carefully “cut” the trace between the ends as indicated in the pix. You will also want to remove the “blue” covering material from the area you cut as well as at the ends of the trace where you need to solder the sync wires (1 brown and 1 grey). Look carefully at the pix – you will notice that I created a “testing” pad at the cut to validate my connections (using a multi-meter).

f) Placing your multi-meter in “continuity” mode (Ohms reading), test the trace for “open” after you “cut” the trace. THIS IS AN ESSENTIAL step on each trace modified. If you do not verify that you’ve completely severed the trace so that it is “open” you cannot expect the mod to work and you may find yourself having to go back and “re-cut” them (too much work). Once you’ve verified that the trace is properly cut (open – no conductivity), move on…

g) Now, lightly twist the brown and grey wires together (this will aid in avoiding signal interference) and strip (remove) a tiny (1/16th inch) portion from the end of both the brown and grey wires from their ends and “tin” them.

h) Tin each solder point on the trace ends (one end is the tip of a micro surface-mounted capacitor – be careful here not to apply too much heat with the iron).

i) Now carefully solder the brown and grey wires as illustrated in the pix.

j) Retest the trace to ensure it is still open and test for continuity between the DB-9 interface connector (brown is pin 6 and grey is pin 5) and each side of the trace where it is cut (that’s why I scraped away a “test” pad on the trace where it is cut).

If you’ve followed these steps carefully so far and the continuity tests confirm good results, you are ready to move on…


k) Before re-mounting the Display screen to the Display Assembly, you may wish to “cover” the exposed surfaces which were scraped away (when you removed that “blue” material) with a non-conductive coating (I did not). Re-mount the Display screen and replace the Phillips head screws removed earlier. Take care to not pull too hard on the brown and grey sync wires when doing this as you do not want to damage your work and have to go back and fix it later. Once the screws are replaced, re-solder the screen frame tab (you un-soldered this earlier) back to the circuit board where it was originally soldered before (here is where that solder wick used earlier will pay dividends)