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Midway Lazarian Maintenance 2022

02/06/2022 - Northwest Pinball and Arcade Show (2022)

Zaccaria games at the Northwest Pinball and Arcade Show Zaccaria games at the Northwest Pinball and Arcade Show
Midway Lazarian, no picture

Trouble began on Show Day 1 with no picture. The monitor was still energized and the game wasn't playing blind so I swapped in the spare game PCB. That bought a few more hours but then again, the game had no picture and wasn't playing blind. Sometimes on power cycle there was a picture and I did catch one occasion where the game was playing, the picture would go blank and the sound would freeze on, then it would come back on again and resume. The game was withdrawn to the dead zone.

25/07/2022 - Game PCB #194 repair

Midway Lazarian main PCB on the bench Midway Lazarian graphics issues Midway Lazarian with Arduino ICT

On the bench the main PCB had a blank screen. Checking IC 11C (2621) with a scope found:

1 hi with lo pulse 14 hi
2 floating 13 lo
3 floating 12 clock
4 hi 11 clock
5 lo 10 clock
6 hi 9 clock
7 lo 8 lo

IC 11C (2621) outputs didn't look correct and replacing it brought the game to life. There were still some misplaced lines on the first sheet only. I suspected that there were specific line effects that were confirmed by looking at the MAME driver. A quick scope probe through IC 12H,13H,14H,15H (LS86), IC 12I,13I,14I,15I (LS85) didn't reveal anything obviously wrong. Working back to IC 14F,15F (2114) MAME confirmed that this effect RAM was write-only and thus couldn't be directly tested by the Arduino ICT. Using "RAM Write All AD" to set all RAM with Data == Address showed similar flickering line artifacts as was seen in the game. Checking IC 14F data bus outputs with a scope found spikes & intermittent noise-like signals. IC 15F data bus outputs were all good looking square waves. I suspected IC 14F (2114) was bad and replacing it fixed the line effects.

01/08/2022 - Game PCB #200 repair

Midway Lazarian main PCB on the bench Midway Lazarian IC 11C Signetics 2621

On the bench the main PCB had a blank screen. Checking IC 11C (2621) with a scope found that there was no CSYNC output on pin 1. Replacing IC 11C (2621) fixed the game. For both game PCBs I was able to find older but ceramic Signetics 2621 in the hope that they'd be more reliable than the plastic versions.

03/12/2022 - Game PCB #200 bench test

Midway Lazarian main PCB on the bench Midway Lazarian main PCB on the bench Midway Lazarian main PCB on the bench

Testing the game PCB back in the cabinet found that the game wouldn't coin up. The main PCB was removed and setup on the bench using the Quasar matrix input adaptor plugged into J4 to test:

Checking the Lazarian schematics confirmed that the cabinet only used the COIN 2 input and the PCB was declared working pending further investigation in the cabinet. The spare PCB swapped into the cabinet was coining up and playing OK, however.



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