Diagnostics and Repairs for 8060 Boards

Information from Jeff

Message 1

Update on Space City.  I got the mpu working.  The problem was in the reset 
circuit.  So, all 4 proms are good and working, no need to verify.  I still 
do not have a manual or schematics, but as soon as I get them I will let you 
know.  I am VERY excited about having a working Space City!  FYI: when the 
8060 cpu first gets power, before the cpu comes out of rest hold, it 
displays the two decimals that I described earlier, then after a valid rest 
signal on pin 7 of 8060 it pauses... ( I think the 8060 is strobing in data 
from the prom at this time) then it boots and displays 78.XXX and high score 
2.XXX.XXX. I will get the exact #,s for you when I have done more testing. 
There is a micro relay on the board that unshorts a RC pull up, then 
triggers a Schmitt trigger inverter to drive pin 7 of 8060 high and into a 
"run " state.
I hope this tid bit of info helps you or someone sometime with a Zac pin of 
this vintage; they are well built pins and would be a shame for any to end 
up in a landfill cause of a small circuit problem.

Message 2

this is what I know so far.

8060 mpu info:

ac input connector: 1/connettore-a

AC voltage readings from left to right, ground ref. on the bottom of R? 100
ohm 1/4 watt resistor close to mount hole in center of board.  Also same
ground buss the battery is connected to.



Boot sequence:
39 ohm resistor ( R137) is released from ground through micro relay = power
on.  A RC circuit pulls reset line high(+5) to reset both ram and 8060 gets
high on pin 7 = run  .... through ic11 inverter driver in =1to 2 then 3 to
output =4  About 4 seconds after 8060 gets high on pin 7 all pop bumpers
flash on/ off rhythmically ( attract mode) and the display switches from (
recent score? )= .101.010  to (high score) 2.1.d0.800

But, now after a bit of testing the recent score and high score values have
changed from what I originally seen when the mpu booted the first time.  The
latest development, after accessing the audits in test mode once.  Now  the
mpu will only display  F's in all segments , flashing like it is trying to
display recent score and high score. The cycle is aprox. 8 sec.

Attached, please find two photos showing the 8060 mpu  and MY reset hack
witch is to pull the end of R137 from circuit and ground to buss ground.
Then a few seconds after switching the power on, I lift the ground from the
end of R137 just like the relay would normally do. I still have a problem
with the relay part of the reset circuit; but I am waiting on manual and
schematics to arrive before continuing repairs.

Hope you find this info useful and it helps someone somewhere save a Zac pin
from the land fill.

I can try to answer specific questions you have... and will certainly share
any info/ docs. I receive when I get them.  I am putting together an old PC
to run a PC-10 eprom reader / tester to get the software documented.

0212 & 0213 = mpu and reset hack; also shows -5, 12 and 5 volt buss
0212 & 0213 = mpu and reset hack; also shows -5, 12 and 5 volt buss
Img_0215 = what display looks like before reset.
img_0216 = after boot, high score attract mode.
img_0218 = after boot, recent score attract mode.

Information from Laszlo

The schematics for Space City have many errors. Use the updated (hand drawn) wiring diagram in the Games and Documentation section, especially for connector CN2.