Hardware Amendments

From Arcade Tester AR81
Jump to: navigation, search

Mark 1 External ADT Clip Fix[edit]


1) Cut two tracks on solder side of board as indicated in picture bellow. (You need to sever the cross bridge)

Trace Cut

2) Insert wire link on PCB side as indicated in Picture Bellow (You need to reattach the Link you cut without crossing it)

Wire Link

Thats it. ADT will now function correctly.

Mark 1 VRAM Write Pod Amendment[edit]

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


VRAM Write Circuit

Note This circuit is only needed for Mark1 Testers, Made and Shipped in 2016 All Mark 2 Testers will incorporate this circuit within the Tester

Mark 2 Z80B Upgrade[edit]

* ONLY RELEVANT FOR Mark 2 Testers made During 2016 *

Z80B compatibility

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.

Z80B Upgrade

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)

Z80B Upgrade

Z80B Upgrade

  • Remove the LS00 Chip, which hopefully will be socket-ed, and lift up pins 4, 5, & 6, then reinsert the chip.

Z80B Upgrade

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)

Z80B Upgrade

And that's it, the mod is complete.