My Alien Poker does this random tilt thing - I'm pretty sure it's not a REAL tilt. You don't hear any of the usual "Awws" before it does this. It's just WHAM! "You Fold." and end of ball. This seems to happen when the game is warm.

I REPLACED BOTH SIDES OF THE 40 PIN INTERCONNECT -- As I knew several of you would ask if I did it. Sorry, Just a little testy about this as I spent the better part of an hour doing it, and pretty quickly after I started playing, it did it again. Hmm.. The game wasn't hot at that point, since I had the game off for that period of time while I was replacing them.

One thing I did notice, is that the driver board has several of those huge resisters along the right side of the board that seem to have gotten very hot. The bands have melted, or somehow shifted, and slid together on some of them. There is also noticable brown discoloration on the back of the the board in that same area. I've seen those do this before on several games, but never seen it cause these random tilts.

It seems like it could almost be a switch matrix problem, but it happens at the strangest times. I've never been good at switch matrix issues, so I guess I'm praying that isn't the cuprit here. Maybe it's something like a secret Heh, or one of the decoder chips on the driver board?

I could speculate all day, but my shotgun approaches rarely do much for the problems they're trying to solve. Anyone?

-Brian

Wow! That was quick, and LOVE some of these ideas.. Particularly the remove the switch row connector as a way to isolate the game. When I started doing this a couple of years ago I was scared as hell to remove ANY connectors from any of the boards while a game was turned on. In my previous life as an IT guy, well, as a teen in the 80s, I had screwed up a FEW pieces of hardware doing that sort of thing. But in this case it makes complete sense, Since the matrix has to be "up" in order to start a game.. Does it really matter if it's the send or receive plug? Those two on the upper right side of the driver board, hmm?

As for clipping the diodes for the tilt mechs, that's another great idea. I had a Pinbot that would do this exact same thing. Wish I'd tried that before I threw in the towel on that game. But, it had been going on for so long, and I'd replaced so many diodes, and it would wait until I was sure the problem was fixed before it'd happen again, that I ended up having a bad taste in my mouth about that game.

-Brian

That's sort of hard to play with the plug disconnected like that. The ball keeps going in the kickout holes - 3 of them - and I've got to dig it out of there with my finger. Anyway, It doens't seem to want to tilt with the glass off. So strange.

More diagnosis input: I was putting credits on it, and I noticed it caused points to score! And the right saucer to eject. So I did a switch test and found that two switches cause the entire row to fire-

Center Coin causes itself, (5), and 13, 21, and 29 but NOT 37. 37 is the right bumper, which doesn't seem to make even when I actuate it manually- Replacing that now after realizing this.

Also, HS reset, switch 8, causes the rest of IT'S row to fire, 16, 24, 32, and 40.

Replacing that diode on the right pop bumper and I'll report back.

-Brian

I took the Plug off and tested Column 1 for ground, and it wasn't. Pin 2J2 Pin 9 reads about .02V as opposed to the 4.8V or so that the others read. It seems to trace back to IC17, a 7406. I replaced that but still no luck. Back to the PIA now? Is it very likely one of the other components between J2J and IC17 have failed?

I've got the test chip, and a logic probe, so I guess I could hook this up to the bench PS and test that PIA in place. Looks like it's Pin 10 that drives that column.

If anyone has any suggestions, I'm all eyes and ears.

-Brian

Well, the test rom says Pin 8 of that PIA/IC11 is always low.

Am I reading this schematic wrong?

-Brian

I've replaced all the chips in line with this thing. The PIA, as well as the 7406- ALL the pins on the PIA dance with the test chip, But Pin 2 of IC17, as well as it's associated pin 2J2 Pin 9 always read low.

It seems like Pins 1 & 2 of that IC17 are the ins and outs of that particular pin, Column 1. and Pin 1 seems do dance as it's connected (and continuity checked) with it's associated PIA pin, but the output of that chip reads nothing.

Anyone a Wiz with this test chip?

-Stymied in Driverland

It ended up being a little glob of solder.

IMG_6192 (resized).JPG

Well, I guess this falls into the 'Connectors, Connectors, and Connectors' subheading. I'm guessing someone tried to re-flow the header pins and got a little carried away.

Still, I learned something doing this (Besides the inner workings of PIAs, and the 4806 or whatever that IC17 was) and that's that start from the simplest, and work outward. Before diagnosing it at the chip level - sure these things go to hell from time to time - ALWAYS look for the obvious, look the board over with a fine tooth comb to determine what the last guy may, or may not have done correctly.

I know for myself, when I go to do something on a game, and then when I go to go back to playing it, Whatever comes up, I always think back to the last thing or repair or whatever I did to the game, and was there something involved in that that didn't work out the way I planned it. I'm sure the guy re-flowing this header had the best intentions, but if the next day when it was displaying this odd tilting behavior (I'm still not sure how that exactly exhibited itself - why did it only tilt once in a blue moon? and why did it seem to only happen when the game was hot?) If he had gone back to his last repair, this reflowing thing, and observed the silver blob, this wouldn't have been an issue.

-Brian

I'm thinking most people don't have a decent solder station, and I know a lot of people swear by those solder suckers, but for me, that was a poor substitute. It's like trying to sew with rebar or something. Right tool for the job. Also, I've come across more "hacking" on these boards than I can take. I understand now why board work people always say, 'If you tried to fix it yourself and failed, don't even send it.'

Is there anything that can be done about solder pads of through-hole connections being pulled off? The solder doesn't take to the tube that is left. trying to solder to it from the top side is a poor alternative - but I guess maybe the only alternative if a board has been abused in this fashion (Not that I didn't do a few of them in my early days as well) but being gentle, and getting ALL the solder out of a connection is definitely better than getting a crowbar and yanking a chip out of it's socket!

-Brian