Tempest will not start game

mrsodapop

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Hi all,
Been pulling my hair out on this Tempest for months. First it would play blind, then found the 15/-15v regulators bad on the video section. I replaced the 2 regulators, the pots, and electrolytic capacitors.
Now I have a nice image, that is flashing free play on screen, but now the start buttons are not flashing, and can't start a game. I put it in diagnostics, and do not seem to get any reaction when pressing either player start buttons, zap,or fire. On one test screen there are letters/numbers in lower right that count up if I turn spinner slowly. I tried replacing the POKEY that is associated with buttons, but did not change any thing.
Any ideas on what to try next
Thanks for any help
Aaron
 
Reflow the PCB header pins (on both boards) for the interconnect cable that runs between the two boards. This should be done on all Tempest boards, if it hasn't already been done.

If that doesn't work, you can also try replacing the other pokey.

-Andy
 
Thanks for the reply, header pins were checked/reflowed, along with a good check over on the rest of PCBs. Also the 2 POKEYs have had the sockets replaced. I will try replacing the other POKEY, and report back.
Aaron
 
This is not a pokey issue. Sounds as if your game is not fully booting. If the buttons are not flashing (and it is in free play) then your game is not running. The two areas that are always problematic on Tempest PCBs are the ROM sockets and the edge connectors. Try pushing on the ROM chips while the game is on (you can reach them via the coin door) and see if the game does anything. If it does it's more than likely those sockets. Good luck.
 
OK, swapped POKEYs around, but no change. Checked edge connectors, and continuity to buttons-OK.
Thanks for any other info.
Aaron
 
Lesbenito- At this point I am also feeling that the POKEYs are not it. I will check to see if there is any change by pressing on ROM sockets. I also went back to check my work, and don't see any mistakes(not that there could be though). As game did play(blind) until after I replaced the faulty 15&-15 V regulators and pots on video section and electrolytics on main PCB.
Aaron
 
Pulling and verifying ROMs, cleaning the legs with a Dremel wire wheel or fiberglass pen, and cleaning the sockets with DeOxit are the first things you should do to any Tempest board. Sorry, I'd figured this was already done.

Also, be sure to check the +5V voltage on the aux board, to a ground on the aux board, in addition to checking +5V on the main board. Sometimes the aux board voltage can be lower than the main board, so it's important to check them separately.
 
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Thanks andrewb,
I don't have a way to verify ROMs, but can pull and clean legs on ROMs, and try and get cleaner in sockets. Also will verify +5 on both boards.
Aaron
 
probably worth mentioning, the Tempest at the shop wouldn't run at all. it wound up being 1 (or more) of the bitslicers on the smaller math board. one of them visibly had the center blown out of it. not sure what causes a failure of that magnitude.

once I dropped new bitslicers in, the game was at least able to play blind then and the buttons flashed again. :)
 
It's not just that pressing the P1 and P2 is ignored, what's interesting is that they are not being lit even though the game knows it's in free play.

If you have a logic probe I'd check for activity on pins 1 thru 6 of the LS139 at B5 on the AUX board as that controls the POKEYs and the LS174 that lights the LEDs.
 
Finally got back out to check game, so here is were things are at.
Aux. board voltage is 5.13vdc
Pressing on ROMs does not seem to change anything.
Checked pulsing using L.P. on pins 1-6 on (LS139) B5: Only pulsing on pin 2, pins 1,3-6 are stuck high
Would this indicate an issue with B5? Or is there another issue before/after it?
Thanks for ideas
Aaron
 
It explains why you are seeing the troubles you have, but not yet what is causing them.

Pin 1 of B5 comes from pin 7 of B4, but pins 2 and 3 are address bus lines coming from the main PCB by way of the interboard connector, which should always show a bunch of activity.

B4 also takes signals from the interboard connector as inputs, and if you probe them (pins 1-3) I'd suspect you'll see a lack of full activity. Without good inputs, you won't get good outputs (through B4 going into pin 1 of B5 or through B5 going out to turn on POKEYs or LEDs).

If you go back to the test screen do you have an 'M' in the middle of the screen?

Signs point to the interboard connector.
 
douglasgb- Thanks for the reply, I went out and checked B4 pins 1-4. Pins 1&4 were high, 2&3 showed activity. Test screen does not show any letters in the middle.
The interconnect pins were reflowed a while ago. The pins also LOOK clean and shinny, but the interconnect cable is obviously original.
Would the next step be check continuity between boards? Or would it be best to just make a new cable(yuk!)? Or is there another section I should check?
Aaron
 
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