Battlezone
Active member
Midway Space invaders (upright L-shaped PCB).
Less interesting fixes
Replaced the dodgy mains plug.
Lost the key so reached through the coin door to unscrew the lower back panel.
The wife used her finding-superpower to locate the key.
Symptom #1
No fire missile sound.
Used a scope on chips E4 and F4 and confirmed the signals toggle as the fire is pressed.
All the diodes in this area checked out ok on a meter.
Solution #1
Desoldered, added sockets and replaced M4 and P4 (both LM3900).
Swapped for LM2900 which apparently has a higher temperature rating
and otherwise identical specs. That fixed the problem, so I went back and
confirmed that only one LM3900 had been bad and needed to go
in the bin.
Symptom #2
The brightness of the moon obscured the lower part of the screen
Solution #2
Replaced a standard white light tube (that someone had stuck in there)
with a Black Light (BL) tube. Also tried a Black Light Blue (BLB) tube, but
that was no good at all in this cab.
To Do
Replace the a couple of dead bulbs.
Edit: EU233 12V 4W car bulbs are confirmed to work well
http://www.ebay.co.uk/itm/-/281344112176?roken=cUgayN
Replace the screen overlays.
Edit: Done. I used these in the end.
http://www.ebay.co.uk/itm/-/361090359207?roken=cUgayN
Battlezone2016-04-22 10:54:08
Less interesting fixes
Replaced the dodgy mains plug.
Lost the key so reached through the coin door to unscrew the lower back panel.
The wife used her finding-superpower to locate the key.
Symptom #1
No fire missile sound.
Used a scope on chips E4 and F4 and confirmed the signals toggle as the fire is pressed.
All the diodes in this area checked out ok on a meter.
Solution #1
Desoldered, added sockets and replaced M4 and P4 (both LM3900).
Swapped for LM2900 which apparently has a higher temperature rating
and otherwise identical specs. That fixed the problem, so I went back and
confirmed that only one LM3900 had been bad and needed to go
in the bin.
Symptom #2
The brightness of the moon obscured the lower part of the screen
Solution #2
Replaced a standard white light tube (that someone had stuck in there)
with a Black Light (BL) tube. Also tried a Black Light Blue (BLB) tube, but
that was no good at all in this cab.
To Do
Edit: EU233 12V 4W car bulbs are confirmed to work well
http://www.ebay.co.uk/itm/-/281344112176?roken=cUgayN
Edit: Done. I used these in the end.
http://www.ebay.co.uk/itm/-/361090359207?roken=cUgayN
Battlezone2016-04-22 10:54:08