Asteroids repair

The save kit is usually added to a working board.
BUT ... it might eliminate any bad ROM socket issues.

Needless, you need to check the 6502 socket (into which it will be installed) and the VID ROM socket(s).

The Braze high score save board is a good investment in the long-run ...
 
I'm not sure what to do at this point. The high score kit came in, got a new vector ROM with it and a new 6502 chip. I tried replacing the 6502 chip first in the original socket but it didn't work, p1 and 2 lights lit but just one small dot on monitor, no watchdog resetting taking place. Which I thought was weird so I installed the entire kit and removed the old EPROM as well. Still wouldn't work. P1 and p2 lights lit but only be small dot appears on monitor.

Removed everything and installed the original parts back into it. Again the same thing, one small dot on monitor and p1 and 2 lights lit. So it's no longer resetting for some odd reason even with original parts...... I don't really get it.

It's worth noting the chip in machine was a 6502A and the chip that came with the kit was a 6502AP. But that doesn't explain why the original parts are now not giving me the same symptoms....
 
Simply removing and replacing a chip sometimes changes the behavior and indicates the legs are dirty and/or the socket is unreliable.

Use the kit since you have it and it eliminates three ROM chips and sockets. Make sure the new vector ROM is oriented correctly and no legs are bent. Same for the CPU installed in the kit and the kit itself. Then put the game in self-test and turn it on (configured as above) and see what self-test yields.
 
Simply removing and replacing a chip sometimes changes the behavior and indicates the legs are dirty and/or the socket is unreliable.

Use the kit since you have it and it eliminates three ROM chips and sockets. Make sure the new vector ROM is oriented correctly and no legs are bent. Same for the CPU installed in the kit and the kit itself. Then put the game in self-test and turn it on (configured as above) and see what self-test yields.


Forgot to mention self test, it does/changes nothing now. Both with the kit installed and original parts. Flip the switch and it continues doing what it was doing with no change whatsoever. :(
 
Forgot to mention self test, it does/changes nothing now. Both with the kit installed and original parts. Flip the switch and it continues doing what it was doing with no change whatsoever. :(

If the game were working you could switch from game into self test, but if it's not working you must be in self-test before you turn it on.
 
Make sure your clock circuitry is working properly, and that you're getting all of the sub-rate clocks, as well as the 12MHz master clock.
 
If the game were working you could switch from game into self test, but if it's not working you must be in self-test before you turn it on.

I actuallt tried it both ways because I wasn't sure what the proper process was, but either way, same results. Thank you for explaining it for me.
 
Make sure your clock circuitry is working properly, and that you're getting all of the sub-rate clocks, as well as the 12MHz master clock.

Alright, Ill do some research on that next, thank you.
 
Still plugging away with this. Came across a couple things.

1. Found a resistor(?22k ohm?) where one side is broken off (see picture). So that clearly needs to be fixed. If someone could point me in the right direction to make sure I get the correct one that would be great. What do they call this style of resistor? If I could get it from my local Radio Shack that would be even better. Any idea if this alone could cause these issues?

2. I originally thought the connector to the pcb could only be connected one way. However it appears it's not keyed and could be connected the other way (flip it 180 degrees). See second picture. The wires and zip ties etc would make it difficult to flip it so I find it hard to believe it's flipped around but I just wanted to be sure.

3. I ordered a new socket for the cpu, seeing as the symptoms have gone from constant resets to solid lights on P1 and 2. So I'm thinking the connection in the sockets is questionable. Ordered a new big blue and cap kit for good measure as well.
 

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thats not a resistor, its a capacitor. It wouldn't have anything to do with your current problem but will have an effect on sound once you get it working.

I'd be very surprised if Radio Shack had that part.

http://www.jameco.com/z/MY-22K-22-F...tml?CID=GOOG&gclid=CL7mxqeW79ICFUeCfgoddwEEgA

your edge connector is positioned correctly. If it weren't and the game was powered up you would have a lot of other problems.
 
- That's a capacitor, not a resistor. It's part of the sound circuit, so some of your sounds will be messed up without it. Any 0.22uF cap rated 50V or more will work. Note that new ones may look smaller/different, but as long as it fits, it'll work.

- The connector goes the way you have it in the pic. Note where the pins are missing, and you'll see no wear on the respective contacts on the PCB. The connectors on these games typically go the way the wires naturally 'want' to go, as they often take shape after 35 years of sitting.
 
To diagnose a non booting asteroids you need to do the following:

1. Verify that all roms are good. Do this with a eprom programmer and the relevant mame rom set. If you are using the high score kit, then that would eliminate the three program eproms (assuming you have revision 2) but it doesn't eliminate the vector roms.

Like the previous posters have mentioned, you should ideally check/replace the CPU socket and Vector Rom socket if you suspect anything. They are known to go bad all the time. A reasonable method of testing if your sockets are good is to hold the probe on reset pin 40 and simultaneously lightly press down on the chips. If you notice the reset pin changing then it's likely a bad socket.

2. Check pin 37 for clock signals. If you are getting rapid pulsing then it's likely your clock signal is good. If not you should check the clock circuit. This consist of mainly C4, B4 and B5.

3. Check pin 40 for reset. This should tell you a lot to what is causing the problem. Thing to note is that the reset pin should momentarily go low on power up and then stay high if working. This is necessary to get the CPU to boot. If you find that this doesn't go low you should check the reset circuit for a fault. The following chips should be checked for correct logic function. B6, C6, D5, E6, D4.

4. If the reset pin is pulsing high and low rapidly, there is a high chance there is a problem with your address circuitry. Before that check the buffers at B2 and C2. Check data sheet on those two buffers and check logic signals to see if they are working as normal.

5. Address circuitry consist of the following chips. E4, D6, E5, C6, E4 and L3. You will need to probe these chips. If any of these chips are behaving badly it will cause the game to not boot. Again use schematics and datasheets to check if these chips are behaving as they should. Look for floating pins, stuck pins, pins that should be flip flopping when they are not. Socket and replace any chips you suspect to be bad.

6. Once all this is done, the game should theoretically boot to at least test mode (you still may not get sound/video) where it will tell you if the ram is working.

You should do all this without the CRT plugged in to be honest. You are going to get a horrible hole in your CRT if you don't. There is no need for visuals at this stage.

Once you get to test mode you can then hear what else needs to be fix.

HTH
 
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To diagnose a non booting asteroids you need to do the following:

1. Verify that all roms are good. Do this with a eprom programmer and the relevant mame rom set. If you are using the high score kit, then that would eliminate the three program eproms (assuming you have revision 2) but it doesn't eliminate the vector roms.

Like the previous posters have mentioned, you should ideally check/replace the CPU socket and Vector Rom socket if you suspect anything. They are known to go bad all the time. A reasonable method of testing if your sockets are good is to hold the probe on reset pin 40 and simultaneously lightly press down on the chips. If you notice the reset pin changing then it's likely a bad socket.

2. Check pin 37 for clock signals. If you are getting rapid pulsing then it's likely your clock signal is good. If not you should check the clock circuit. This consist of mainly C4, B4 and B5.

3. Check pin 40 for reset. This should tell you a lot to what is causing the problem. Thing to note is that the reset pin should momentarily go low on power up and then stay high if working. This is necessary to get the CPU to boot. If you find that this doesn't go low you should check the reset circuit for a fault. The following chips should be checked for correct logic function. B6, C6, D5, E6, D4.

4. If the reset pin is pulsing high and low rapidly, there is a high chance there is a problem with your address circuitry. Before that check the buffers at B2 and C2. Check data sheet on those two buffers and check logic signals to see if they are working as normal.

5. Address circuitry consist of the following chips. E4, D6, E5, C6, E4 and L3. You will need to probe these chips. If any of these chips are behaving badly it will cause the game to not boot. Again use schematics and datasheets to check if these chips are behaving as they should. Look for floating pins, stuck pins, pins that should be flip flopping when they are not. Socket and replace any chips you suspect to be bad.

6. Once all this is done, the game should theoretically boot to at least test mode (you still may not get sound/video) where it will tell you if the ram is working.

You should do all this without the CRT plugged in to be honest. You are going to get a horrible hole in your CRT if you don't. There is no need for visuals at this stage.

Once you get to test mode you can then hear what else needs to be fix.

HTH

Awesome post, thank you.

So far I have replaced all the capacitors. Replaced both the socket for the CPU(and the chip itself) and the vector rom socket, as well as the Rev 2 vector rom itself that I got with the kit. And verified all voltages from AR board and power supply are correct. So I believe like you said the problem lies in the remaining EPROMs. I don't have an EPROM reader but I do have a logic probe so I can check those signals as you suggested. I'll update once that is done.
 
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