Together Again To Tear It Apart

From this…

…to this…

…took about 3.5 hours over two sessions. Or, to put it in relative terms, about a third of the time I put into Sorcerer, and even more favorable compared to Comet… Though I can’t say exactly how much better since I didn’t keep time for that one. I’m very pleased with how streamlined my workflow is becoming. During disassembly I basically break the playfield into a 2×8 grid and work my way through each section, photograph it, remove parts in logical (to me, at least) groupings, and bag and label each subassembly.

I found that the most time consuming part of reassembly on the previous two tables was filling in the blanks where I hadn’t done enough documentation during teardown. Being extra methodical with breaking this one down saved me a ton of time in recomposing it, despite the significant increase in complexity from System 9 pins like Comet and Sorcerer to the more feature laden System 11 based Big Guns.

Given there are 2-4 layers of parts to remove to get to any given bulb, I wasn’t thrilled at the prospect of having to tear things down to get to short-lived incandescents, so I decided to go the LED route. I used Pinballbulbs.com non-ghosting LEDs in warm white for the #44 general illumination and cool white for the #89 flasher bulbs on the top of the playfield and in the area behind the ‘wall’ at the back.

I think the results look pretty nice. The photo makes it look like a lot of the plastics are blown out by the brightness of the LED bulbs but in person they have a nice bright, even light behind them that shows off the art and lights up the playfield nicely without being overpowering. After seeing how the top of the playfield looks I’m going to go forward with replacing the lamps under the inserts on the bottom of the playfield, and replace the lamps in the backbox as well. The previous owner installed a color ‘coordinated’ LED kit in the backbox and it makes the art look really bad, since the color of the LEDs completely overpowers the translite’s coloration.

Now that Big Guns is back together I’m going to swap it in for Sorcerer at the office and bring that one into the shop for some MPU diagnosis… After having several hundred balls played through it without a hiccup during a party the company hosted I turned it on the day after and it was resetting randomly during gameplay. Poking around (very literally) narrowed the issue down to a bad connection or flaky component in the lower right corner of the MPU board, but tracing it further than that is more than I want to do with the limited tools I have at the office.

If you’re interested in seeing what the disassembly process looks like (or have one of these things you’re trying to piece together yourself), see the gallery below for all of the reference photos I took while tearing this thing down:

Sorcerer! You Are Done, Mortal.

It turns out the issue with the outhole kicker solenoid wasn’t due to chips dying, it just looked that way because of the way the symptom manifested, and the way I was diagnosing. I’d been swapping in new 7408 chips, and that would let the solenoid work properly for a couple games, before it would go back to locking on.

Last week I ordered a logic probe to dig further into this problem, and once I had it in hand it took about five minutes to discover that, no, the chip was not dying. What was happening is that one of its input pins was not getting any signal, and as a result the output signal that controls the solenoid was not being provided. Using the probe I checked the trace to that input pin, and found it was showing what it ought to. Pushing on the chip socket would sometimes restore connectivity, too. The problem was just a bad connection, and the intermittent behavior I’d observed was happening because every time I swapped the chip it flexed the area around the socket, occasionally in a way that briefly restored the connection.

Whoever worked on the board last used a one piece socket, and I didn’t really want to yank the entire thing out since it was evident several jumpers were installed underneath it and I didn’t care to deal with that spaghetti unnecessarily. I ended up adding a Kynar wire jumper from input pin 1 on the chip to the next component back from it. Brought the board up on the bench and checked the chip, and its inputs and outputs for the outhole solenoid now looked good.

The lack of audio was super simple too. I found that one of the pins in the connector for the volume adjustment potentiometer had its retaining clip pushed in, allowing it to work its way out of the connector when plugged into something. It wasn’t visible at a glance but I noticed the wire move when I was reinstalling the MPU board after doing the solenoid driver repair. Fixed the loose pin, plugged everything in again, and the soundtrack is back!