Re: Where to start on Missile Command PCB repair

Suggestions:

Processor is 6502A, NOT 6502. Make sure someone didn't stick the wrong
chip in there.

You can go low-tech if you want, take your DVM and measure processor pin
37. If the clock is there it should read around 2.5 volts. 0 or 5 means
clock is missing.

Measure pin 40 (NRESET). If 0 volts you're stuck in reset. If around 5
volts either game is running or watchdog isn't working. Should be pulsing
between 0 and 5.

On Thu, Oct 31, 2013 at 8:57 PM, Grant Thienemann <
grant.thienemann@gmail.com> wrote:

> Hey Guys,
>
> So I replaced the 6502 socket and all the EPROM sockets as well, did a
> quick check and the crystal is on the board, though I have no idea if its
> good or not.
>
> Anyway went to turn on the game and I don't get a loud hmmm anymore, but
> nothing is appearing on screen and the game still appears to be dead.
>
> I need to either figure out how to use my catbox, find a 6502 pod, OR find
> my logic probe . . .
>
> -Grant
>
>
> On Thu, Oct 31, 2013 at 9:02 PM, Matt J. McCullar <mccullar@flash.net>wrote:
>
>> **
>> Nice work so far, Grant. Here is where you can find images showing how
>> to "strap" _Missile Command_ boards for different EPROMs:
>>
>> http://www.ionpool.net/arcade/atari/MC2708.jpg
>> http://www.ionpool.net/arcade/atari/MC2716.jpg
>>
>> You can modify each one of the 4164 RAM chips to "behave" like a 4116.
>>
>> How to use a 4164 chip instead the original 4116:
>>
>> - Bend pin 1 und 8 upwards so they no longer go into the socket's
>> connectors.
>> - Connect Pin 8 and 9 with one another through a short piece of wire.
>> - Make sure pin 1 and 8 are not in contact with any other components
>> nearby.
>> - Insert the chip like this into the socket.
>>
>> (Some gamers who own Williams games like _Defender_ have zillions of
>> these RAMs to modify, and it's a lot easier for them to just modify the
>> board rather than all the chips. _Missile Command_ doesn't have very many,
>> and that's why I like to just upgrade the chips instead.) You do not have
>> to change any jumpers on the _Missile Command_ motherboard for this.
>>
>> I don't have a _Missile Command_ board within arm's reach right now, but
>> the crystal is probably labeled "X1" on the motherboard. It looks like a
>> small rectangular silver can. (Unless it's missing!)
>>
>> Hope this helps!
>>
>> Matt J. McCullar
>>
>>
>
>

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Received on Thu Oct 31 22:44:14 2013