Mark 1 External ADT Clip Fix
* ONLY RELEVANT FOR EXTERNAL ADT BOARDS *
1) Cut two tracks on solder side of board as indicated in picture bellow. (You need to sever the cross bridge)
2) Insert wire link on PCB side as indicated in Picture Bellow (You need to reattach the Link you cut without crossing it)
Thats it. ADT will now function correctly.
Mark 1 VRAM Write Pod Amendment
This circuit is only needed for Mark 1 Testers, Made and Shipped in 2016 All Mark 2.0 & 2.1 Testers will incorporate this circuit within the Tester
The CPU pods will work just fine on their own, pin for pin. but if you require VRAM write access then a small Circuit is required.
The Circuit will need to be attached between the DATA lines of the Tester and the CPU Socket on the Test board. along with a few other lines depending on the CPU used
Schematics are bellow showing the Circuit and where to attach
- WAIT needs to be connected to Z80, Tester and Circuit
- +5v is coming from CPU SOCKET pin. (game board Power) Not from the tester.
- CPU Pin M1 and REFSH will need 10K Ohm Pullups
- This Circuit will also allow Hardware with Z80B CPUs to be tested
Note: Mark 2.0 do not have Z80B addon, only 2.1. Please see bellow
Mark 2 Z80B Upgrade
* This circuit is only needed for Mark 2.0 Testers, Made and Shipped in 2016 All Mark 2.1 Testers will incorporate this circuit within the Tester *
Bellow is a picture of the Circuit in a Mark 2, the Red Traces/Components represents removals and the Blue Traces represent New Circuit and the Orange Components representing New Components to be added.
The best way to perform this mod is to use spots that are already on the board.
- Remove 220R Resistor and install either a Jumper or a Zero Ohm Resistor
- 220pF and 10nF Caps can be installed where the 330pF Cap spots are, 220pF on the Left and 10nF on the Right. They are on the correct pins for the mod, Through Hole or SMD will work. (Please take note of the solder blob on Pin 5 of the Chip going to the GND leg of the Cap. This is needed)
- Remove the LS00 Chip, which hopefully will be socket-ed, and lift up pins 4, 5, & 6, then reinsert the chip.
Now is the Fun Part, Modding in the 74LS74 Chip into the Circuit
- Bend out all the Legs of the Chip do they are all flat, you can also cut off the thinner parts of the legs
- Solder Pin 1 and 13 together
- Solder Pin 2 and 6 together
- Solder Pin 5 and 11 together
- Solder Pin 8 and 12 together
- Solder Pin 4 and 10 and 14 together
- Pin 9 is left Floating
Now your 74LS74 is prepared for its final connections.
- Solder Pin 1 or 13 to Bottom of 74LS00 Pin 4 (make sure Pin 1 and 3 of 74LS74 are still connected as well)
- Solder Pin 3 to Bottom of 74 LS00 Pin 5
- Solder Pin 8 or 12 to Bottom of 74LS00 Pin 6 (make sure Pin 8 and 12 of 74LS74 are still connected as well)
- Solder Pin 4 or 10 or 14 to Bottom of 74LS00 Pin 14 (VCC) (make sure Pin 4 and 10 and 14 of 74LS74 are still connected as well)
- Solder Pin 7 to Bottom of 74LS00 to Pin 7 (GND)
And that's it, the mod is complete.