Pinballs

It's been a while since I last discussed the Creature. The reason for that wasn't because there was nothing to say, it was because there was a lot going on and I wanted to wait until I've made enough progress to warrant a story :)

First things first, big news: the Creature is 100% operational, everything works. YAY! Picking up where I left off, here's in a somewhat chronological order what happened on that machine for the past few months.

Considering what we've seen before (see previous posts), two things needed immediate attention:

• I replaced the melted bumper coils AE-26-1200 (all 3 where dead, melted down to the nylon sleeve, and had broken steel armature links). They were driven by the damaged bank on the Power Board.
• I completely repaired the damaged bank on the Power Driver Board (replaced all components, rewired missing tracks). Needless to say, this wasn't a pleasant task, see for instance
  
  
  
  

After that, the Power Driver Board seemed mostly functional, except that:

1. +5V had a nasty tendency to vanish quite abruptly
2. Solenoid 4 didn't work
3. Row 4 of the lamp matrix didn't work
4. G.I. string #2 didn't work
5. Switch matrix column 4 didn't work (unrelated to the PDB though, see below)
6. The mirror motor didn't work
7. The hologram motor worked intermittently

1. was fixed by isolating and fixing two dry solders: on BR2 and C5. They weren't obvious, I had to gently bend the board in various directions to figure them out.
2. was investigated a bit further: grounding the metal tab of the pre-driver transistor Q75 (TIP102) triggered the solenoid. Thus, the main (TIP36C) transistor was good, and the pre-driver had to be changed. After replacing Q75 with a new TIP102, Sol 4 was functional.
3. was a bit tricky because it really was non-obvious: only by following the signal path from the driver transistor back to the uplink to the CPU board was I able to determine that a track was cut at U4 pin 17 on the solder side. A very faint, yet sharp cut was enough to disrupt the signal. Nothing a drop of solder couldn't fix though :)
4. turned out to be due to one (or more?) short-circuit #555 lamp(s) in the G.I. string in the backbox. After I replaced all the #555s, the string worked like a charm.
5. was a problem on the CPU board (switches are wired to the CPU board): a track was cut at U20 pin 15 on the solder side. Fixing it was not enough, it turned out U20 had suffered too much abuse from previous repair attempts and had one dead logic input gate. Replacing U20 altogether brought all the missing switches back to life.
6. turned out to be a cut red wire from J106-5 (and not J107-5 as the doc suggested) to the motor's triac driver board J1-1 connector, which was providing 24VDC to the optocoupler.
7. was a dry solder at the fuse holder on the triac board, no biggie ;-)

At this point, the machine is 100% operational and we had a lot of fun playing it for a while. Now, it's undergoing massive cleanup, pictures will be posted soon!