Asteroids help and questions

Digger

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I just picked up a nonworking Asteroids game and would like some help to see it I can get it going. I seem to have all of my voltages and when you turn the game on the player1 and 2 buttons flash but nothing else. You can not coin the game up and it you hit the test switch you get one low tone and then a deeper one. The monitor only has one small dot in the bottom right corner. I switched big blue with one out of a parts Pole Position PS and the game acts the same when turned on. I know the replacement big blue was just as old but I was hoping for a different result to tell me that was the problem. When you power the game on the LED on the main board comes on and stays on. The LED on the deflection board starts off dim and works its way up then stays lit.

Are the tones telling me that in need a new ROM at E2 and where is the best place to get them? Is this how my monitor should act if the game board is not working correctly? I have a logic probe and a DMM as well as an oscilloscope (not quite sure how to use it yet). I can solder and have no trouble replacing parts...it is just finding the bad part on these game boards that always has me lost. Where should I look or test next?

Thanks for any help you can give.
Scott
 
First things first, sounds like your power supply is at least nominally working. Measure the voltage you're getting at the game PCB edge connector (not at the AR board). [if you don't know what something means, or how precisely to do somethig, don't be shy... ask :) ] Should be 5.0 give or take 0.1V or so. If it's lower than say, 4.8, or higher than about 5.2, I'd adjust it (using the pot on the AR board).

The fast blinking start button LEDs indicate that the CPU is constantly resetting (known as "watchdogging", as the watchdog circuit is repeatedly resetting the CPU). It's possible (but not particularly likely) that properly adjusting the +5V will fix that.

Regarding the test mode beeps... Thank you! for reading the manual (or backdoor sheet), 4 out of 5 people asking questions haven't bothered to read the dang manual. Yes, that beep pattern would indicate a bad RAM (not ROM) at E2. IIRC, all the RAM in Asteroids is 2114 (there may have been some odd-ball versions of the board with different RAM, but I haven't seen one of them). Bob Roberts sells it. You might buy several in case some others are bad (the test only beeps the 1st bad one it finds... there might be more). It'll have to be desoldered; then a socket soldered in; then install the 2114 into the socket.

Aside from that, you might try re-seating your EPROMs (pulling them out and re-installing them). The sockets on these are notorious problems. Replacing them is a bit of a PITA, so many people (me included) have opted to use the Braze HS save kit, which also replaces all of the EPROMs: http://www.brasington.org/arcade/products/hs/asteroids/ With it installed, you can remove the original EPROMs and not worry about the crummy sockets being a problem.

You edge connector might need some attention too. Make sure it isn't burned/charred, or doesn't get really warm with the power on. If there's a significant voltage drop between the AR and the PCB... time to clean the PCB edges and re-pin the connector housing.

Too soon to tell anything about the monitor, as you can't really expect any output in game mode if it's watchdogging, nor in test mode if the RAM has an error. The red LED on the monitor PCB is known as the "spot killer". When it is on, it indicates that it thinks there is not input from the game, so it's turning off the beam (so as to avoid burning a spot in the center of the screen). If any of the 3 "christmas tree light" looking neons on the monitor PCB are lit... that's another problem entirely.
 
Aside from that, you might try re-seating your EPROMs (pulling them out and re-installing them). The sockets on these are notorious problems.
DarrenF's advice is sound. I'm going through a restoration now, and I just fixed my asteroids blinking issue by replacing the sockets with higher quality ones.
I first reseated the Roms and notice a change in the blinking, which is what prompted me to the problem.
But be sure to verify your voltages first!
 
I do have all of my voltages and they are correct. I am getting 5.2vdc on the A/R board and dead on 5vdc on the game boards test points. I had re-seated the chips before I posted but will give it another try tonight. Both the edge connector and PCB fingers look nice and shiny. I will order some new RAM chips and a new big cap then post back when the new parts are installed. Is there anything else I should get while I am placing my order? None of the neon lamps on the monitor board are lit. Thanks for the help.
Scott
 
I removed four 2114 chips off of a Galaxians board and piggy-backed them on chips M4,R4,N4 and P4 with no change in the way the game acted. E2 according to the test was the 2114 that was bad but it is not a 2114. It looks to be a ROM/PROM chip. Is it better to go with a High Score save kit then to get new ROM/PROMs ? All of the Chips that have sockets (5) all have SCANBE sockets. Could the scokets on one or all of these be bad ? Not a big deal for me to remove and put some SIP sockets in if that could be the cause of my problem. Is there any way to test the chips with a logic probe? If I get a chance tomorrow I will put some new sockets on the board and see what happens.
If you have any other ideas please let me know. The board is a A034986-06.
Thanks,
Scott
 
I removed the sockets from E2 and the CPU and put in new SIP sockets with no change. I am going to remove and replace the other three sockets and see if that helps. I was also going to repin the connector as the game started drawing strange lines then showed what looked like the test pattern while making some "beeping" noises I had not heard from it before, but I can't seem to get it to do it again. I am hoping that there are some bad pins just not making good contact. Could the CPU be bad? If I am putting an order in for some parts should I get a new CPU as well ?
I need to get some other things done around the house so it might be a while before I can get back to this. Please if you have any ideas shoot them my way as I am lost with video game boards...but hopelessly adicted :)
 
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