Tempest RESET RESET RESET

rcranetx

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So I've been trying to get a Tempest board up and running for a couple of weeks now but cannot get it to stop reseting (WDCLR). What I've done:

1. Replaced CPU and CPU socket (socket was bad)
2. Replaced one ROM socket
3. Checked all ROMs against rev 2 source - Good
4. Continuity checked all data and address lines - Good
5. All clocks clean
6. Replaced big blue
7. Disabled WD, still nothing
8. dip switches not in freeze
9. No aux board, CP, coin door connected
10. Almost poured gasoline on it and blew it to high heaven

Seriously, I've looked up and down KLOV but I'm not sure what else to do here. Any recommendations? Any at all?
 
Could be bad address or data lines. Get schematics, and start checking them with a logic probe. It won't tell you if the data is correct, but it will show you if a line is stuck high or low.

You're getting the reset because the program isn't running and it's not sending the code to clear the WD.
 
Thanks Talon. I have a scope they seem to be doing what they're supposed to and my data in the ROM is good too.
 
Pay close attention to the enable lines on the ROMs plus the enable and R/W lines on the RAMs. If they aren't coming active when they should then the system will never be able to boot and will be stuck in watchdog reset.

Also, where in Texas are you? Talon and I are in the DFW Metromess.

RJ
 
Hi CM, I'm in Allen. I'll be at the Auction tomorrow. I'll have a look at those enable lines.

BTW: I'll have a Its on like DK t-shirt tomorrow if you're going.
 
I'm in Lewisville and Talon is over next door to you.

I'll be there in the morning for the 9am gathering but not sure what I'll be wearing yet.
 
If anyone going to the auction has a couple 24-pin sockets to sell, pls bring with you and I'll pay you more than fairly.
 
Well WDCLR is High in Test mode now and the reset is not as often as before in game mode but is still occurring on a slower frequency.

Is test mode a subset of the ROMs that wouldn't timeout?
 
Voltage is right at 5V - 5.1V

I'm 100% sure the reset line is not going low in test mode but is going low in game mode. No doubt.
 
Ok. So if test mode is not reseting, but the game is. Then you have a problem on the vector side of the game.

Do you get an image in test mode, is the Aux board known good.

Could have a problem with the Aux board that's causing the reset.
 
Not completely.

So far it's had Bad socket on E1, Bent Pin on L/M1, Bad socket on M/N1, Bad Roms on P1, R1, and R3. Custom Prom at D7 was in backwards, Some minor problems on the Aux board. But it plays blind now. Still working on the video out problems.
 
Not completely.

So far it's had Bad socket on E1, Bent Pin on L/M1, Bad socket on M/N1, Bad Roms on P1, R1, and R3. Custom Prom at D7 was in backwards, Some minor problems on the Aux board. But it plays blind now. Still working on the video out problems.

Wow... and the backwards PROM wasn't blown?
 
Well I ran a checksum on it, and it tested good. Tried in a known good test board and it worked. I'm as surprised as you. Thought I was going to have to burn a new one.
 
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