Tempest Troubles... any ideas?

adamzero

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Hey gang...

Well, my Tempest (since the day I got it) has had a strange quirk. Hopefully someone can drop some knowledge on what might be the issue.

It has a monitor that's been refurbished within the last 18 months (right before I got it) by arcadecup in green bay, WI... but I'm doubting it's the monitor here.

The game will fire up fine and play perfect for maybe 5-20 minutes. Then, during game play screens everything will lose perspective. Like, the shooter/enemies/framework of the tube will just go crazy and sizes will be all over the place. The monitor's 'sound' changes as well. During this time, game sounds continue, and gameplay does too, though you can't really see what you're doing.

Once your game is over, the high score screen and the TEMPEST title screen are just fine & the monitor 'sounds' fine during these. But during the simulated play in attract mode, it goes back to being all messed up looking.
The monitor also gets an overall pulsing flicker as well. Certain elements remain just fine, even when the game goes goofy, like the score.
DSCN0161.jpg

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It goes goofy at random.. there's nothing that seemingly triggers it. Sometimes it'll just happen when the game is running in attract mode, sometimes in the middle of a game.

Another curious anomaly is if you power down the game, it will take multiple power-ups to get it to come on correctly...sometimes I let it sit for awhile and then at times it comes back on normal... BUT, during the times when I power it on and it's still goofy, it shows 40 1/2 credits...
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But once it runs through the high score/title screen and does a round of goofy looking attract play, it shows 40 credits.
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So, is this a board issue? Something with the voltage? I'm relatively new to this, so any help would be appreciated.

Thanks everyone.
 
The graphics problems are due to the aux board.

If it happens after warm up I would suspect loose alu chips or proms on the board. Can also be caused by poor connection with the interconnect cable.

Easy fixes are to reflow the interconnect headers on the main and aux board. Reseat the alu's pokeys, and proms on the aux board.
 
I agree with the others. Looks like a math box error. But it could be the cable between the boards. Mine had the same problem and it turned out one of the pins on the aux board had a cold solder joint (intermittent) connection.
 
Ok, I switched it into test mode both during & before the glitchy stuff. No errors, mathbox or otherwise, showed up.

I also noticed that when I plugged a small fan into the same power strip the game was plugged into (by itself, no other games) and turned the fan on to blow across the boards, the monitor got wavy. Like slow pulsing waves. No other glitches, just slow, subtle waves. I unplugged the fan and they instantly disappeared.

I played for another 20 minutes and the glitch never came back.

So... knowing that no board errors show up, you guys think it might have to do with the wiring/edge connectors or the monitor itself? Maxstang, did you just replace the wiring then to fix it?
 
Ok, I switched it into test mode both during & before the glitchy stuff. No errors, mathbox or otherwise, showed up.

I also noticed that when I plugged a small fan into the same power strip the game was plugged into (by itself, no other games) and turned the fan on to blow across the boards, the monitor got wavy. Like slow pulsing waves. No other glitches, just slow, subtle waves. I unplugged the fan and they instantly disappeared.

I played for another 20 minutes and the glitch never came back.

So... knowing that no board errors show up, you guys think it might have to do with the wiring/edge connectors or the monitor itself? Maxstang, did you just replace the wiring then to fix it?
I wouldn't 100% trust what test mode says. A monitor won't display things like 40 1/2 credits on its own...that has to be coming from the board. I would check both the aux and main boards for cold solder on the pins that interconnect them as Maxstang mentioned.
 
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I came across the same problems with my Tempest board. The screen flipped upside down. Checked the dip switches, not the problem. I even replaced two of the 8 position dip switches. The screen was intermittent, sometimes the spot killer LED would come on and then go away. Then the monitor seemed to pulse, and the chatter from the monitor was not sounding normal and seemed to be struggling. Removed every chip on both boards and tried a second set of backup chips. I even swapped the cable from both boards and used my backup cable. I know it was the board because I installed my boards into another working Tempest game and the same problems were showing on the monitor and the coin mechs would start chattering like it was possessed.

So I refloated the solder on all the cable pins for both boards, prayed to the Arcade Gods and plugged my board back into the harness and fired up my Tempest........Yahoo!!!! It worked. The screen is solid, the coin mechs are working, 40 and half credits disappeared and the spot killer was gone.

Dropped a few credits in the game and played for couple minutes. No issues and playing like a dream.
 
I came across the same problems with my Tempest board. The screen flipped upside down. Checked the dip switches, not the problem. I even replaced two of the 8 position dip switches. The screen was intermittent, sometimes the spot killer LED would come on and then go away. Then the monitor seemed to pulse, and the chatter from the monitor was not sounding normal and seemed to be struggling. Removed every chip on both boards and tried a second set of backup chips. I even swapped the cable from both boards and used my backup cable. I know it was the board because I installed my boards into another working Tempest game and the same problems were showing on the monitor and the coin mechs would start chattering like it was possessed.

So I refloated the solder on all the cable pins for both boards, prayed to the Arcade Gods and plugged my board back into the harness and fired up my Tempest........Yahoo!!!! It worked. The screen is solid, the coin mechs are working, 40 and half credits disappeared and the spot killer was gone.

Dropped a few credits in the game and played for couple minutes. No issues and playing like a dream.

Good to hear!
 
When I acquire a Tempest PCB, the very first thing I do on them is re-flow the interlink connectors. I wish it was always that easy.
 
You won't see the "M" for Mathbox error unless you first flip the test switch to test mode, and then either power the game up or hit the reset button on the main pcb. Some likely suspects are bad sockets for any/all of the 4 mathbox chips, and bad solder joints at the interconnect cable pads.

How I was finding my bad sockets was I would get the M to appear on the test screen, then fidget with the sockets and zero in on which would cause the M to intermittently go away. Replace the socket. Same thing with messing around with the interconnects. Reflow all the solder around those pins and make sure they look good and the cable connector housings look good.
 
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