Re: Where to start on Missile Command PCB repair

Hey Matt,

Thank you for the information! I actually have two missile commands I'm
trying to get working at the moment, my stand up which I never got working
and my cockpit which I picked up this weekend. I want to get both working,
and in reality I would like to get at least 3 board sets working because I
have an original Super Missile Attack add-on daughter board that I would
like to put in a machine as well! Here is what I've figured out so far
from yesterday afternoon, I didn't get to work on it last night because I
was watching my kids!

[image: Inline image 2]

1st. I had checked the voltage at the ARII not at the Missile Command PCB.
The voltages I had scene at the PCB were -5.1 volts, +11.75 volts,
and +4.68 volts. I adjusted the +5 volts slowly with my fluke connected to
the test loops on the pcb until the +5 read +5.02, the other two voltages
stayed the same. I re-tested 4 of my 6 PCBs and with basically the same
result, nothing on screen, though two boards cause the coin counter to just
go berzerk.

2nd. I have the all the new sockets to replace all the socket-ed chips on
the PCBs with new sockets. I'm replaced the ram sockets on my best looking
PCB and in taking all the ram out I did lift one trace but I was able to
fix it with trace wire on the solder side of the PCB. I have a Hakko 808
desolder gun, I find people either love it or hate it, I love mine, so
taking the sockets off the PCB is too difficult, I just have to be
carefully of lifting a trace wire on the parts side. Also I have a Weller
soldering station as well, analog not digital that works well. I'll work on
replacing the 40pin 6502 socket tonight and the 6, I think its 6, sockets
for either the EPROMs or PROMs that go on the PCB.

3rd. As of yet I haven't been able to get any of my PCBs to do anything in
test mode, however if what you are saying about the sockets is correct,
then that could be the problem. I noticed with one PCB I plugged it in, put
in test mode, nothing and when I went to check the voltage on the PCB the
6502 wasn't even installed on the PCB. So I think one major problem with
all my PCBs are the sockets.

4th. I haven't looked at the crystal yet, and I'm not even sure where it's
located, I'm going to go look at the schematics now to see where on the PCB
it's located. I know I don't have any spares, where can I pick those up at?
Does anyone have a part number to digikey or does Radio shack carry them?

5th. I know you can replace the 4116 with 4164 ram however from what I've
found online you need to change jumpers OR the wiring harness for the PCB,
are there jumper settings for the ram on the PCB?

6th. I have heard about the 2708 and 2716 EPROMs however I haven't been
able to find any information those far on how the jumpers should be set on
the PCB, do you have a link to that information somewhere?

Thanks
Grant

On Thu, Oct 31, 2013 at 12:19 AM, Matt J. McCullar <mccullar@flash.net>
wrote:
> Howdy, Grant! I've worked on several "Missile Command" boards, and here's
> what I've learned...
>
> * Replace all the sockets. If yours are original, they are over 30 years
> old now and their contacts are just as corroded as the pins on the chips.
> Yes, it takes practice to desolder all those things effectively, but new
> sockets will eliminate a great many headaches. (Replace the socket
> underneath the 6502 processor, too.) [You may find some ripped-up
> printed-circuit traces underneath these sockets; some people pry out those
> chips without being careful, so you may have even more soldering to do.]
>
> * Is the crystal still there? The main clock is generated from a 10.000
MHz
> crystal, and all too often when I see a "Missile Command" board, that
> crystal is just flat-out missing. Even if it's still there, it should be
> solid in place and not easy to move around with your finger.
>
> * I like to replace all of those old 4116 RAMs with newer 4164 RAMs, that
> have been "tricked out" to resemble 4116's. You can find information on
how
> to do this on the Internet; it's not that difficult. The 4164 chips are
> newer, use only +5 volts (instead of several bus voltages as the 4116s
do),
> and may be much easier to find on the market these days.
>
> * A real curve ball: Atari designed the motherboard so that it could
accept
> two different kinds of EPROMs: 2708s or 2716s. There are lots of solder
> pads (jumpers) next to the ROM sockets that tell the hardware which chips
> are being used. You must look at these very carefully; a pad may be cut
or
> it may be intact (or resoldered). 2708 EPROMs use several bus voltages
and
> those pads must be configured for such; 2716 EPROMs hold twice as much
> memory and use only +5 volts, but again those solder pads must be
configured
> for them. If the wrong type of EPROM gets plugged into a socket that
> doesn't have those pads set correctly, it may destroy that EPROM. (I like
> to "strap" the boards for 2716s, as they are far easier to obtain and work
> with. If you have a "Missile Command" board that has EPROMs in every
single
> socket, they are probably 2708s; if only half the sockets are populated,
the
> chips are probably 2716s. But someone else in the past may have swapped
> chips around without knowing the difference.) [If you use just 2716s, you
> only have to replace half of the sockets!]
>
> * Take lots of careful notes. Be sure the correct EPROMs/ROMs go in the
> correct sockets.
>
> Defend cities!
>
> Matt J. McCullar
>
>
> -----Original Message-----
> From: owner-rasterlist@vectorlist.org
> [mailto:owner-rasterlist@vectorlist.org]On Behalf Of Grant Thienemann
> Sent: Wednesday, October 30, 2013 6:32 AM
> To: rasterlist@vectorlist.org
> Subject: RASTER: Where to start on Missile Command PCB repair
>
>
> Hey Guys,
>
> I've got a stack of Missile Command PCBs that don't work and I need
> some guidance on where to start. Here is what I have done with my
> first PCB.
>
> Checked the PCB in test mode, doesn't nothing, just an audible hum
> Felt all the chips to see if any are hot, none were warm to the touch
> Replaced all the 4116 ram with sockets and cleaned the ram legs, still
> nothing.
>
> I have the following equipment at my disposal though honestly, I don't
> know how to use some of it.
>
> HP Logic comparator
> HP 5004a <-- haven't used them yet
> Atari Catbox <-- haven't figured out how to use it correctly yet
> Fluke 9010a but no 6502 pod :-(
> Logic Probe <-- haven't used it yet
>
> Any information would be fantastic!
>
> Thanks
> Grant
>
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Received on Thu Oct 31 09:19:53 2013