Arcade Collecting > Pinball

Gottlieb System 80b switch matrix question

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ed12:
hi
 the link u posted is for a system 80 not a system 80b
the dif is the 80b used olny 2 eprom's 1 of which is on a piggy-back board
also the :riot: chip control's the matrix

ed

ed12:
hi
now as ic11/12 are your strobe's ie send singal
and ic13/14 are your return's :from switch-diode-matrix:
and u found no known diode short's ?
also as u are board level repair >fussy-little-pesky-trace's<
do not remove the :riot: chip unless u know,how to remove them without
doing damage to the main board,in the trade we call them burchtered
and will not touch them
u must do a few more chk's.look at the riot for a soild gnd..ie pulled low
or a constant high ie pulled high..this will apply to the i/o line's olny
this will tell u if u have a bad riot or a bad ic or a bad switch and or a bad diode in the matrix
go slow think it out
look at the board and copy a pic in i can tell u if is a 80/80a/80b/80c
c the point please
post back

ed

brad808:
OK I have a bit of an update on this. I replaced z11,z12,z13,z14,z15. The game booted up and I went to test mode all switches showed closed. I credited up and played 2 or 3 games. Everything seemed fine. My girlfriend played 2 or 3 games then she only got 2 balls one game, the next game she only got 1 ball. Now when I boot it up it simply shows weird graphics in the display. When I hit the left advance button the game tries to start as if I'm hitting the start button and then the left ball capture keeps triggering a kick out. Can you explain in more detail how I can check the riot chip? I'm guessing by the fact that she game worked after replacing those chips that they were a side effect of a greater problem. Obviously something is going wrong and fried those chips.

I've checked every diode I can possibly find with a multimeter, physically looked at all the switches and still haven't been able to find anything.

ed12:
hi
the riot chip is a bugger to chk
unless u have a spare system80/a/b/c on hand ?
let me ask u 1 question before we go to debug mode
is there any evedince of battery damage ?,u can tell this by looking
at the trace's below where the oringal battery would be
and see if the trace's are a tad lighter :green: then the reset
if this has happened >common< then we can track it down to a bad/brocken trace,which is what it put's me in mind off
but we need to start there,40 pin's can be indanunting for alot of ppl
to un-solder-re-solder

ed

brad808:
There is no battery damage that I can see. A previous owner has done the battery mod and the ground mods on this game. I've checked all those connections and they seem to be fine. Last night somebody sent me this via email last night. It's basically a bible of system80 repairs. Before this I'd simply been looking on the internet and reading the schematics. This is what it says.



--- Quote ---The RIOT Chips.
Chip U4, U5 and U6 are 6532 RIOT chips. These are large 40 pin chips, and often
they fail. If any one of the RIOT chips fails, that can lock up the CPU board. RIOT
U4 handles the switch matrix, and this chip is particularly troublesome. If any of
RIOT U4's input TTL chips at Z11/Z12 (7404 switch strobes/row) and Z13/Z14 (7400
switch returns/columns) fail, this can lock the CPU board. Also the Z15 switch
returns enable chip (7432) can cause switch matrix problems too:
For example, if Z12 is missing or failed, the CPU board will not boot. Also if chip Z14
is missing or failed, the CPU board comes up immediately with "000000" in the
displays (like the slam switch is open). Note row chip Z11 and column chip Z13 can
be missing and the CPU board will still boot (because it doesn't handle the slam
switch).
Switch matrix chips Z13, Z14 (7400 returns/columns) input pins 1,2,4,5,9,10,12,13
can be viewed with a logic probe. They should be strobing, as they are the switch
returns, and connect directly to the playfield switches. None of these should be
stuck low! If one is stuck low, the CPU board may not boot (by forcing the IRQ low).
Then test the Z13, Z14 output pins 3,6,8,11. If these outputs are all strobing, but
an input is not, replace the chip (7400). If neither the input or outputs are strobing,
then the U4 RIOT chip is probably bad. Also note that Z15 (7432) switch enable chip
could be causing problems here too (and this also uses one gate from Z12, pins
12/13).
Strobe/Row Connector Chip In Chip Out to RIOT
S0 A1J5-2/A1J6-1 Z12 pin 2 Z12 pin 1 U4 pin 24
S1 A1J5-3/A1J6-2 Z12 pin 4 Z12 pin 3 U4 pin 23
S2 A1J5-4/A1J6-3 Z11 pin 12 Z11 pin 13 U4 pin 22
S3 A1J5-5/A1J6-4 Z11 pin 10 Z11 pin 11 U4 pin 21
S4 A1J5-6/A1J6-5 Z11 pin 6 Z11 pin 5 U4 pin 19
S5 A1J5-7/A1J6-6 Z11 pin 4 Z11 pin 3 U4 pin 18
S6 A1J6-7 Z11 pin 2 Z11 pin 1 U4 pin 17
S7 A1J5-9/A1J6-8 Z11 pin 8 Z11 pin 9 U4 pin 16
The switch matrix strobes/rows should also be tested. This is mostly chip Z11, with
two gates on Z12 also used. Check Z11's input pins 2,4,6,8,10,12 (these go directly
to the playfield switches). Then check Z11's output pins 1,3,5,9,11,13. Also Z12's
input pins 2,4 and output pins 1,3 should be checked.
In my opinion many offending CPU board issues can be attributed to a failed U4 RIOT
chip. It seems to cause more problems than it should. And often the fail is not black
and white. That is, the game will sometimes boot, but other times may not. This
situation can get worse and worse with time, until finally the game won't boot at all.
It's like the U4 RIOT internally desolves, but at a slow rate. I have seen this many
times, and it's rather odd compared to other manufacturer's games (where they
work one day, and the next day they don't, with no "sometimes it works" factor).
--- End quote ---


Unfortunately I don't have a logic probe around here but I may try and search locally to find one. That will help rule out the u4 riot chip. Unless there is another way to test it. Would the riot chip cause the z11,z12,z13,z14 chips to go bad or simply not function correctly? It seems the chips themselves are getting fried (I'm not sure which one specifically yet) because when I replaced them the game functioned "normally" for a few games. If I do get a logic probe I believe it may help me determine which chip (and even which gate on the chip?) is going bad. That may help me trace it down the line.

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