Zaccaria Phoenix Maintenance 2022
20/03/2023 - Phoenix PCB #001 repair
This PCB didn't boot and had no video sync. Starting with the 74LS163 video counters
on the bottom video PCB found:
- IC 1 output pins 11 -> 14 - all active
- IC 4 output pins 11 - idle, 12 -> 14 - active
- IC 12 output pins 11 -> 14 - all idle
- IC 13 output pins 11 -> 14 - all idle
Using the HP logic comparator, IC 1 and IC 4 tested OK. Checking IC 12 & 13 found that
clock input pin 2 was idle, labeled VCP-00 coming from the top PCB via interconnect pin 2-11.
On the top PCB this translated to signal DCP-00 output from IC 23 (LS08) pin 8, idle low, and
input pins 9 & 10 both idle low. Working back to IC 30 (LS74) found input pin 2, H9, idle high
and clock input pin 3 active. I suspected H9 was a horizontal counter bit and should have
been active. Signal H9 came from interconnect pin 2-13 and was output from IC 7 (LS04) pin 10
who’s input pin 11 was idle low as output from IC 5 (LS74) pin 8. Output pin 9 was also
idle high with input clock pin 11 active. With its ~Q input fed back to D, it should have
been toggling on every clock cycle so I suspected IC 5 was bad. A piggyback on IC 5
(LS74) brought the game back to life and replacing it fixed the game.
Play testing the game found the game sounds slightly off. Using the Arduino ICT to test
through the component sounds versus the recorded reference sounds from a known good
PCB found:
- SCntA1 - Higher pitch
- SCntA2 - Higher pitch
- SCntA4 - Higher pitch
- SCntA8 - OK-ish
- SFrqA1 - Trill really slow
- SFrqA2 - OK-ish
- SNoiA1 - OK
- SNoiA2 - OK
- SCntB1 - OK, slightly lower pitch
- SCntB2 - OK, slightly lower pitch
- SCntB4 - OK, slightly lower pitch
- SCntB8 - OK
- SFrqB - OK, slightly lower pitch
- SFltB - OK
Whilst many of the sounds had some variation from the reference PCB, the most clearly
very different was SFrqA1. The sound trigger outputs at IC 29 (7405) looked OK.
Closer inspection found that capacitor C16 was 2.2uF but the schematic showed it as 0.47uF.
I didn't have any 0.47uF capacitors to hand so 2 x 0.22uF were fitted in parallel (0.44uF) for
C16 that fixed the slow trill and the game play sounded correct. The incorrect capacitor value
was likely an original manufacturing error.
22/03/2023 - Phoenix PCB #006 repair
This PCB was missing a lot of game sounds. On the bench the Arduino ICT was connected and
the component sounds compared against the reference PCB recordings:
- SNoiA1 - Missing
- SNoiA2 - Missing
- SCntB1 - Missing
- SCntB2 - Missing
- SCntB4 - Missing
- SCntB8 - Missing
Starting with SCntB, IC 13 (LS161) clock input pin 2 was idle high fed from IC 48 (555) pin 3.
IC 48 control pin 5 was idle high but did trigger from SFrqB and I suspected IC 48 was bad.
Moving on to SNoiA1 found IC 42 (555) pin 3 making only a single pulse high on trigger and
I suspected it was also bad. Replacing both IC 48 (555) and IC 42 (555) fixed all the
game sounds.
23/03/2023 - Phoenix PCB #0077 repair
Still more audio problems, this time a very loud noise was stuck on, possibly the bird
wave wow-wow sound. Attaching the Arduino ICT found:
- SCntA1 - Oscillating randomly
- SNoiA1 - OK
- SNoiA2 - OK
- SCntB2 - Intermittent
A lot of noise was seen on the volume pot that was triggered by any other sound. I suspected
a bad LM324 was oscillating. Poking around with a scope found that touching pin 2 of IC 52
(LM324) with the scope caused the oscillating noise and replacing it fixed the sound.
23/05/2023 - Phoenix PCB #007/GGI01
During pre-show testing on the bench, after a few hours the game had frozen with only the
score displayed. A power cycle brought the game back, but the wings of the birds were the wrong
colour and the ship graphic wasn't quite right. It also intermittently crashed during attract
mode. Since I had a lot of spare Phoenix PCBs, I decided to set it aside and use game PCB #005
as the show spare.
prswan@gmail.com
