PCB Repair: Cruis’n World

Problem

No video.

Diagnosis

Like Cruis’n USA, Cruis’n World runs on Midway V-Unit hardware:

VUnit.JPG
If you squint a lot, it looks a bit like Wolf-Unit…

It’s worth noting that this is a medium-resolution game. Fortunately the cheapo GBS-8220 converter I use for testing will handle that. Despite my best attempts however, the 8220 was unable to detect a signal from this particular PCB.

V-Unit schematics are publicly available (see the Cruis’n USA manual), so the first thing to check was the CSYNC output:

CSYNC.png
(Sheet 13/25)

Here we see pin 5 of U82 versus pin 6. Notice the complete failure to buffer the input signal…

CruisnSync.png
This looks awfully familiar…

One new 7407 later and we were back cruis’n. Or not, as I don’t have the means to test the controls…

Fix

Replace 7407 at U82.

(There’s no sound because the audio section requires 14VAC.)

%d bloggers like this: