Hi, I hope this problem hasn’t been hashed out before but like most of these old machines, the problems are always different. I have a Xenon machine that I’ve had it since around 1999 and it has never been fully playable. The playfield was pretty much trashed (installed an overlay) and the MPU had the usual acid damage; after getting a replacement it was sort of working back in 2008 when I put it away in storage. I recently got it back out and have been going over it trying to get it functional. Apart from the vocalizer board not working, all lights and solenoids function. My problem is the lower, middle and right pop bumpers fire whenever hit one of them gets triggered making the game not very playable (never the left pop bumper though). Looking at the leaf switches, there is plenty of gap in them that they aren’t triggering from vibration. Furthermore, the solenoid self-test shows the same problem. I am lucky enough to have a logic analyzer and I had PB0 - PB3 connected and was able to monitor the data lines from the U11 PIA on the MPU and when the test gets to the pop bumpers, I see the data lines flutter along with the three pop bumpers triggering instead of the data value holding for ~1/2 second like all the others. When I disconnected the solenoid board and monitored the data lines, they did not flutter anymore. I also disconnected the sound board in case it was causing problems with the address lines but to no avail. I replaced U11 with one of the 6820's from the acid ruined MPU and the problem did not change. I guess its possible that there is corrupted data coming into the PIA from the CPU.

Is it possible that I have a ground problem (bounce) between the MPU and solenoid board?

Chris.

I’d buy that if it happened on other solenoids and outside of the solenoid test, which there are no sounds. I did remove the sound card in case there was some foul play but the result was the same. I do get sound, just no voice.

Chris.

Thanks! I’ll look at these mods. The boards are pretty much as they left the factory minus the MPU battery.

Chris.

OK. I finally got back to this problem. I bought a length of braid from Marcos and fixed the cabinet to head ground connection. Not a surprise that this did not fix the problem. I also bought 4 new switches to replace the ones that are in the game (probably original) but before I dove into replacing them, I decided to put some tape between the switch contacts and then run the solenoid test. WOW!! The switches were the problem! I had it in my head that the switch contacts would have been disabled in that self test (being a software engineer, that's what I would do). I suppose they had their reasons. Anyway, off to the next problem....sound.

Chris.