Zaccaria Crazy Kong Maintenance 2023

06/05/2023 - Spare game PCB #PA20230605

A spare Crazy Kong game PCB was bought untested from a Facebook post. Testing on the bench found it working with no issues.

17/07/2023 - Game PCB #AA02832 repair, part 2

The repair of this game PCB was resumed. Coin 1 input was used to trigger the credit sample that then got stuck repeating. Inspecting with a scope found the ~VCTR signal not pulsing.

Using the spare working PCB as a reference, the sample playback circuit was mapped out starting with the AY-3-8910:

pin	signal	pin	signal
14	hi	6	lo
15	lo	7	hi
16	lo	8	hi
17	hi	9	hi
18	lo	10	hi
19	hi	11	hi
20	hi	12	hi
21	hi	13	hi

IC 4R (LS157) pin 1 was high and IC 3M (LS161) pin 9 hi -> lo pulse. Mapping out IC 2P (LS00) found:

pin	signal	pin	signal
1	hi -> lo pulse	14	vcc
2	hi	13	hi
3	lo -> hi pulse	12	hi
4	hi -> lo pulse	11	lo
5	hi	10	lo
6	lo -> hi pulse	9	hi -> lo pulse
7	gnd	8	hi

IC 2P pin 1 lo pulse was measured on scope as ~18mS wide.

• IC 5T pin 1 - hi -> lo pulse
• IC 5V pin 9 - lo
• IC 5V pin 10 - hi

Returning to the faulty PCB working forwards from the AY-3-8910 found a mismatch on pins 7 & 8 versus the reference above. Replacing the 8910 had no effect and I suspected that something was pulling on them. Using the HP comparator to check IC 4R (LS157) passed OK but IC 3R (LS157) compare failed. A quick piggyback check resulted in no sample playback and I suspected it was bad. Replacing IC 3R (LS157) fixed the sample playback.

07/10/2023 - Monitor glass side rail repair

The Crazy Kong monitor glass was broken during transport for the 2022 Northwest Pinball and Arcade show. Both side rails had a cut out at the bottom when the cabinet was previously hacked to take a wood horizontal monitor surround. I decided to repair the side rails to ensure the monitor glass was supported top to bottom.

After using a screwdriver to pick out the remains of the side rail, the resulting rail measurements were a surface segment of 3/4" x 1/2" and a slot segment of 3/8" x 7/16".

A 3/4" square dowel was cut down to make a 1/2" width surface segment and a 3/8" square dowel used as-is for the slot segment. One side still had the slot partly filled and resisted chiseling it out, so the slot segment length was made shorter to fit. The two segments were glued together and set with G-clamps.

Both pieces were tested for fit and sanded as needed.

After masking the slot segments with tape, the surface segment was spray painted matt black.

Wood glue, spacers and G-clamps were used to set the rail repairs in place.

One week later, both rails had set solid.

I'd not yet found a replacement or reproduction for the broken glass that was reinstalled back into the cabinet.

03/04/2024 - Power supply repair

Pre show testing encountered graphics issues on game PCB AA02832. Swapping in the spare game PCB PA20230605 encountered colour issues.

Both game PCBs tested OK on the bench, and I suspected that the 1B1126 power regulation PCB may have issues. Checking with a scope in the cabinet didn't show any significant ripple on the +5V supply, indicating that the main smoothing capacitor was OK, however both connectors were in poor condition such that pressing impacted picture brightness. The regulator PCB was removed and both connectors were replaced.

After reinstallation of the power regulation PCB the game ran without issue for several hours and was declared fixed.