The DC (as I'll now call it) does have a few gotchas, especially when you buy used. These are worth noting here for others who find themselves in the same position:
Symptom: Game discs don't read, no matter how much they are cleaned, how flawless they are (ie. unscratched) and how clean the laser is.
Solution: There seems to be two issues here that happen frequently.
- The Potentiometer on the GD-ROM needs to be adjusted (less likely)
- The disc detection catch is worn. (usual culprit)
I would always go for the latter first!!! I found that adding a small tube of tape around the catch was enough to resolve this issue. The extra millimetres of thickness made the catch more reliable. A simple test to see if this is your issue: put a GD-ROM on your console when it is "naked" (not top on). You must now take absolute care that you in no way look directly at the laser. This may, and doubtless will, blind you permanently. Be careful and do the next step at your OWN risk. I will not be held responsible for your own misadventure. YOU HAVE BEEN WARNED! Okay, you have made sure you are safe? Good. Ensuring there is a disc on the GD-ROM, gently pull back the disc door closed switch. The disk will spin up and will hopefully boot. If this works, you need to add a small amount of Celotape (aka. Scotch tape, Sticky tape, etc) (one wrap, 2 maximum) loosely around the switch. Reassemble and test the disc still reads. One caveat - don't use you most prized disk, as the GD-ROM drive has the potential to scratch the disk, given it is not being played with the extra padding and felt protector in the drive bay. I'd use a CDR with some homebrew or similar on it.
Adjusting the Potentiometer should *always* be your absolute last resort. As I've never done it, I can't tell you how - but there are certainly a few guides out there, as well as Youtube tutorials.
Symptom: Dirty video, lines on screen, general pulsating when the GD-ROM access the disc. (Secondary, random re-sets and when warm, repeated reboot loops, non readable discs.)
Solution: this is very simple. The PSU is having issues. All that you need to do (and I swear this seems so unlikely to work, but really, it does..) disassemble the DC (remove modem, remove 4 screws - one in each corner, turn right side up, lift top case directly up and off), look at the power board (long board along left side), remove PSU wire (carefully, push in the retaining clip and it should come off with little force), remove the 2 screws on the left edge, one at either end (well, one in my case) and gently release the board from the retaining clip. The PSU board will then lift off in an upwardly direction. Note that in the bottom left corner (as you look at the console from the front) or right hand corner (when you rotate the console so that the board is directly in front of you) there are a number of pins (5 or 6) that go up in to the PSU board. DO NOT BEND OR BREAK THESE!! Once the PSU board has been removed, I'd suggest rubbing the pins on the power connector with an abrasive substance (I used a nail buffer - I wouldn't recommend anything too harsh). This probably isn't critical, but given our next step, it would seem worthwhile.
We'll now focus on the pins. Look at them. I guarantee they will be slightly corroded... a thin black residue will be visible at minimum, probably hardly visible. Set at the pins with your chosen cleaning method (again, you are trying to strip a thin layer of corrosion, not drill for oil, so be sensible and don't over do it! You should not be removing a great amount of material!) When done, the pin should look clean. Reassemble the DC (make sure you DO NOT bend any pins!) When you've completed this, turn on the console. Your video will be crystal clear and you'll see no noise at all on the picture! Yes, I was as sceptical as you probably are, especially as the power seems to leave the PSU board in 2 places, but it worked as promised.
Just applying these two techniques has meant the difference between "about an hour of play" and 3 or 4 hours of play (and closing down because I was done, not because the console gave up.)
I'm going to add extra tips here as and when the crop up. I'll also expand on the above if needed.