Asteroids help please!

toolguy

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Got an Asteroids Cabaret to restore. It was bought working all except for the ship shots did not always fire in a round ball. After 2 games at home and the on/off switch breaking in my hands, I decided to restore it then.

Things I did:

Installed the Bob Roberts PCB cap kit.
HV/Reg cap kit.
Monitor/deflector cap/transistor kit.
Replaced the two large caps on the deflection board.
Did not do the deflection resistor delete mod, with wire. My board does not have these two resistors.
Re-flowed solder to all male header pins on all boards.
Checked for cracked/questionable solder joints.
Replaced Big Blue.
Replaced all fuses.
Replaced the on/off switch.
Put in a new crystal for good measure.
PCB connector edge was cleaned, looked pretty good compared to others, so I left it alone. (again, the machine did work)
Replaced 3 crappy Scanbe sockets and re-seated all chips. I know about Scanbe from bringing pinball machines back from the dead and clays guides!
Replaced power cord.


Double checked my work, did not destroy any traces or pads.

Thought I was good to go, so I turned the machine on!

Nothing cracked or poped, no fuses blew. All I get is P1 and P2, steady lit, monitor neck glows (looks good to me), PCB LED ON, Spot Killer LED ON, speaker has slight pop when I turn the machine on, and the monitor has one small dot in the lower left corner. Sometimes the dot moves to the upper right corner.

Searching the Asteroids repair manual on line, all it said for this condition was clean PCB edge and check for loose connection. I did that tonight and no change. I also read that monitor will not display anything until it see's a signal. I searched this site too and nothing like my condition.

Tonight I also removed three chips with dirty legs and cleaned them, I think all were ROM chips. No change still! I also looked closely at the PCB connector and replaced one of the terminals that looked weak and barely touching.

Game will not go into test mode. I flip the switch and nothing happens.


This is how I roll, when I restore a game, I do it all, I do not want to visit 30 year old parts continuiously...

Thanks for the help!
 
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You are correct the monitor has logic (the spot killer circuit) to disable the beam if a valid signal is not present.

Assuming you have a loic probe check pin 40 of the 6502....is it high or pulsing ? Pulsing means the board is in reset and will not generate a signal for the monitor.

You can also check the boards XOUT and YOUT test loops for a signal with the logic probe....they should be pulsing
 
Actually I do not have a logic probe. All I have is a DVOM.

Can I use a DVOM to check? If so, please guide me.

I am pretty technical with things, just need to be pointed in the right direction.


Also Y Gain Pot is gone. Two of its legs are soldered together, not my work.

I do have the POT to replace it with, just wanted to see what it did without replacement since it did work.

Lastly, I have the manual, but do not know what chips are what i.e. the 6502.
 
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The 6502 will be the big 40 pin chip. You can *try* with a dmm but not sure how well it'll work if its pulsing pretty fast. Put it on DC volts (lowest volt setting above 5 volts), put the black on a ground and carefully touch the red to pin 40 - if it shows a steady 5v thats good, if its less than 5v or jumping around chances are its watchdogging.

Reading all your changes, the only alarming/possible thing was the sockets and especially the crystal. I'd try putting the original crystal back on before anything else, then I'd check the continuity on the sockets. If the y gain pot was that way from the get-go, I wouldn't touch it until you get it working again, and chances are that was the original problem. If the y gain is set too high compared to the X, it'll make an elongated picture or shapes.
 
One lesson to learn from this is to do your work in stages and then test it. That way if something quits working you can more readily track down what went wrong. You changed so much all over the game that it's hard to know for sure what happened. It sounds like a board issue but could also be a power issue. Have you checked all the voltages already to be sure they are in range?
 
The 6502 will be the big 40 pin chip. You can *try* with a dmm but not sure how well it'll work if its pulsing pretty fast. Put it on DC volts (lowest volt setting above 5 volts), put the black on a ground and carefully touch the red to pin 40 - if it shows a steady 5v thats good, if its less than 5v or jumping around chances are its watchdogging.

Reading all your changes, the only alarming/possible thing was the sockets and especially the crystal. I'd try putting the original crystal back on before anything else, then I'd check the continuity on the sockets.

OK I will try to check voltage at the 6502 (now I kniow which it is).

I am confused by the crystal. The one I put in is new and I have read a bad crystal can cause it to be dead, plus these are susceptible to go bad. I suppose your thinking is if it worked with the old, put it back in...

I did check continuity when I did the sockets, but can recheck that too.

One lesson to learn from this is to do your work in stages and then test it. That way if something quits working you can more readily track down what went wrong. You changed so much all over the game that it's hard to know for sure what happened. It sounds like a board issue but could also be a power issue. Have you checked all the voltages already to be sure they are in range?

I hear ya on the one thing at a time, I was just waiting for parts and would install things as I got them...

I am not sure how to check the voltages, as this is my first vid restore. I have the manual if you can guide me in on checking the voltages.


Thanks for the help everyone!
 
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Its possible a crystal can fail, but honestly in all the years I've been messing with these things, I've yet to deal with a bad one.
 
Just swapped crystals, no change in the machine.

Learned how to check voltages and got these:

PCB = 5.1V
HV/REG = 5.2V
HV/REG = 11.5V

Voltages seem OK to me.

I re-checked continuity between pin with the sockets I installed, did not get any.

Here is something I did notice... Is there supposed to be a component at "WDOG DISABLE", near chip D?

If so, mine is gone. The manual does not say there shouldbe one and the board does not have like an R15 or something next to it.
 
The +5 is the easiest to check. There is a +5 test point and a ground test point on the board. They are clearly labeled. Check for +5 there. It should hopefully be slightly above 5 volts. 5.1 or something is probably ok.

The others are a little trickier but if you read this thread I show pics part way through the thread of how to do it:

http://forums.arcade-museum.com/showthread.php?t=130269
 
The +5 is the easiest to check. There is a +5 test point and a ground test point on the board. They are clearly labeled. Check for +5 there. It should hopefully be slightly above 5 volts. 5.1 or something is probably ok.

The others are a little trickier but if you read this thread I show pics part way through the thread of how to do it:

http://forums.arcade-museum.com/showthread.php?t=130269

That's what I did to get the voltages above. I did not check at the chip because I cannot determine pin 40. Is pin 1 the top left and pin 40 the bottom right?

I just did not want to cause an issue trying anything on it...
 
OK sorry, I guess you are referring to your post on page 3 and checking voltage at the three transistors. I will have to figure this out and try it.





EDIT:

Is it ground on the board and then each right leg, of each transistor, to the positive on my DVOM?
 
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That's what I did to get the voltages above. I did not check at the chip because I cannot determine pin 40. Is pin 1 the top left and pin 40 the bottom right?

I just did not want to cause an issue trying anything on it...

If you call the end of the chip with the notch the top then pin 40 is the top right and pin 1 is top left.
 
If you call the end of the chip with the notch the top then pin 40 is the top right and pin 1 is top left.

Well, depending on which direction you are looking at the chip from that could be reversed. :) I recommend Google for chip pin numbering so you can see a picture.
 
It sounds like the board is resetting as others have suggested. Double check your socket replacements. All it takes is a solder short between pins or an open connection to stop the CPU from running.

Mark Hooks
 
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