Asteroids Deluxe

blazin06

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Just picked up an Asteroids Deluxe, and of course it has an issue. It powers on fine, but all I can bring up is the test screen. Everything the test screen shows appears to be normal. Once i turn the test switch off, nothing shows up on the screen. I don't hear any tones indicating bad RAM either. Any suggestions? I've already tried cleaning the edge connector, and verified 5volts on the PCB.
Thanks for any help!
 
When in test mode, push some buttons. Do you hear beeps?? IF NOT, you have an audio system issue, and it may be trying to make beeps to indicate a RAM error (but you are unable to hear them).

On the screen in test mode. Are there any letter/number combinations? (Other than the 4 rows of info on dipswitch settings). These would indicate bad ROM(s).
 
Yeah, i hear beeps for every button pressed during test mode. I've attached a picture of the screen in test mode.
 

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OK, you audio is working, so you're now sure it isn't indicating a bad RAM. And it doesn't look like there's any indication of any bad ROM on the screen...

When you switch to game mode:

Do the LED start buttons blink constantly and fast (assuming they light up in test mode, so you know they work)? If so, this is a sign of watchdog resetting.

If not, have you tried coining up and starting a game blind?
 
OK, you audio is working, so you're now sure it isn't indicating a bad RAM. And it doesn't look like there's any indication of any bad ROM on the screen...

When you switch to game mode:

Do the LED start buttons blink constantly and fast (assuming they light up in test mode, so you know they work)? If so, this is a sign of watchdog resetting.

If not, have you tried coining up and starting a game blind?

They don't blink at all when I turn it off test mode. I tried coining it up like you suggested, still nothing :(
Any other ideas?
 
Mmm. Well, we know that:
1) the cpu is functioning, and is able to execute code (as test mode works)
2) the vector generator and output and montior work (as you get a display in test mode)
3) the RAM & ROM appear to be more or less OK (test mode isn't 100% certain, there still may be bad RAM or ROM)

Typically if test mode works perfectly, but it doesn't work in game mode, I'd expect it to be watchdogging. This doesn't appear to be the case for you.

You might try grounding (by using a jumper wire) the "WD DIS" test point. That disables the watchdog reset circuit. (Install the jumper with power off, the turn it on.)

You might try re-seating your EPROMs.

You have a logic probe?
 
No, no logic probe unfortunately.
I'll try re-seating and cleaning the legs on all the EPROMs to see if that helps. Is the WD DIS a spot labeled on the PCB?
Thanks for your help!
 
Yes, WD DIS will be a labeled test point (it'll look like a little ring). It should be relatively close to the CPU.

If you had a logic probe or oscilloscope, I might suggest poking around the NMI circuitry.

As you don't, it's sounding like time to consider finding someone to repair it (unless, or course, anyone has any other suggestions).
 
The non-maskable interrupt (NMI) needs to be working for gameplay, but is
hardware disabled by the testmode switch. Its one way you can have a
game that appears to be working fine in testmode but does not work at
all in gameplay mode. It should be watch dog resetting in that case, but
disabling the WD will not get you any farther in this particular failure case.
I put would put a logic probe on the NMI signal on the cpu and see if it
is pulsing like it should be in gameplay mode.
 
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