As some may know, there is at least one STE Board revision where the PLCC-CPU is not in a socket, but is soldered directly onto the board, which looks like this:
I found out about this when I checked whether I could integrate the STE-Booster in my system. If you look at it, you will see that it requires you to remove your CPU and uses the through holes to be mounted instead of the original CPU. This of course is not possible with my STE revision, since there are no holes, only SMT pads.
We had a lot of ideas regarding this (see this thread: viewtopic.php?f=24&t=68). My first try was a PLCC plug together with an adapter PCB, which failed miserably (see here: viewtopic.php?f=23&t=288). Turned out, that the clock-signal is quite sensible, and that the PCC-plug and my board simply pushed the STE over the edge.
Exxos suggested instead of trying to make the STE Booster fit, I should try to hack it into the board. For this to work, the CPU needs to be isolated from its clock line, to provide it with the new clock line, that is controlled by the booster board. The booster itself needs the following signals to work:
- BG Update: Can be tied to VCC, Signal not needed (see here: viewtopic.php?f=18&t=358&p=2539#p2539)
- BR Update: Can be tied to VCC, Signal not needed (see here: viewtopic.php?f=18&t=358&p=2539#p2539)
- RESET Update: Can be tied to VCC, Signal not needed (see here: viewtopic.php?f=18&t=358&p=2539#p2539)
So what follows now is a description of what I did to get this to work. If you want to do the same, be warned: This isn't an easy mod! You will have to remove the CPU, solder in a PLCC socket, bend up CPU pins that are likely to break, etc. If you make mistakes, you can damage your board, your booster and any parts involved. I for example confused VCC and GND, which blew my CPU AND the GAL on the booster PCB. So be warned!
Update: I found out you don't have to bend up CPU pins, there is in fact a visible trace you can cut. See my update here: viewtopic.php?f=18&t=358&start=10#p2348
Tools I used:
- Soldering station
- De-soldering station, a vacuum pump and good desolder wick
- Temperature controlled hot air station
- Exxos STE-Booster OR Exxos 1.5 Booster (both work, choose one)
- Exxos Fast TOS ROM (alread installed and working)
- A PLCC68 Socket for SMT mount
- wire (I used colour coded, to not get confused)
- leaded solder tin
- Hot glue