Stellar Wars - bumper not working

[Leinhit]

in the repair guide there is lots of info on the "special" solenoids.. but not much on testing the CPU controlled one..

unless I missed a step / test in the above.. I'm a bit stuck.. except for changing those transistors just for the heck of it..


I did see something about reflowing the solder on the header pin on the driver board.. but thought we decided the continuity was good since we fired the solenoid by grounding the TIP120 transistor...

unless they mean another header? Like that one I just mentioned that had weird voltage above?

5 dcv when unplugged , .6 dcv when plugged in...

 

[ELutz]

in the repair guide there is lots of info on the "special" solenoids.. but not much on testing the CPU controlled one..

unless I missed a step / test in the above.. I'm a bit stuck.. except for changing those transistors just for the heck of it..


I did see something about reflowing the solder on the header pin on the driver board.. but thought we decided the continuity was good since we fired the solenoid by grounding the TIP120 transistor...

unless they mean another header? Like that one I just mentioned that had weird voltage above?

5 dcv when unplugged , .6 dcv when plugged in...

If grounding the "tab" of the TIP120 fires the coil....your headers/connectors are good...it also means you've got voltage. Since this is a controled solenoid (not a special solenoid)...the issue is before thhe TIP120 driver transistor. Back tracking, you've got the pre-driver transistor Q26.......then you've got IC2......then you've got IC5 (the 6821 PIA). Your problem is probably somewhere in that. I'd put money on IC2 (which, I think, Lindsey mentioned?). At a minimum, you'll need a logic probe to check those IC's. Trigger the solenoid in test mode (or start a game and do it in game play)....and follow the signal/pules with the logic probe.....until it goes bad.

Edward

 

[Leinhit]

If grounding the "tab" of the TIP120 fires the coil....your headers/connectors are good...it also means you've got voltage. Since this is a controled solenoid (not a special solenoid)...the issue is before thhe TIP120 driver transistor. Back tracking, you've got the pre-driver transistor Q26.......then you've got IC2......then you've got IC5 (the 6821 PIA). Your problem is probably somewhere in that. I'd put money on IC2 (which, I think, Lindsey mentioned?). At a minimum, you'll need a logic probe to check those IC's. Trigger the solenoid in test mode (or start a game and do it in game play)....and follow the signal/pules with the logic probe.....until it goes bad.

Edward

Edward, I must have missed Lindsey saying that part.. or didn't understand it..

I have no logic probe.. so maybe can just replace some of them shot gun like and hope I get the right one?

I'm also not sure about the switch.. I've tested it different ways that make sense to me..

did you see my part about the .6 volt to the one side of switch instead of 5 volts I 'think' it should be? its 5 volts on the driver board pin, but plug the connector back in and it drops to .6.

I have not found a schematic for this game yet.. but will got to work finding that IC2 and the PIA.. and the pre driver transistor.. which if I recall my test seemed ok.. and order new ones to replace them..

appreciate the continued help...

steve

 

[Leinhit]

Edward..

from the repair guide.. same as you described I believe :

The way the driving logic works is as so: the CPU, which is running the game ROM program, wants to energize a coil. It tells the a PIA (Peripheral Interface Adaptor) to turn on the appropriate coil. This in turn drives a 7408/7402 chip, which then turns on a small "pre-driver" 2N4401 transistor. So far this is all done with "logic level" 5 volts. Then the pre-driver transistor turns on a much bigger TIP120/TIP102 transistor. This final link in the chain is what ultimately completes the coil's path to ground, causing the 28 volt coil to energize momentarily.

As I can't find a schematic... do you know which of the 7408/7402 chips run this bumper? is that the same as the IC2 you suspect? I can change the PIA, the 7402/7408 chip, and the 2n4401 (I know which TIP122 is the correct one) I assume the 2n4401 is the one next to the TIP122..

That just leaves the PIA and 7402/7408 chip to find...

Steve

 

[ELutz]

Edward..

from the repair guide.. same as you described I believe :

The way the driving logic works is as so: the CPU, which is running the game ROM program, wants to energize a coil. It tells the a PIA (Peripheral Interface Adaptor) to turn on the appropriate coil. This in turn drives a 7408/7402 chip, which then turns on a small "pre-driver" 2N4401 transistor. So far this is all done with "logic level" 5 volts. Then the pre-driver transistor turns on a much bigger TIP120/TIP102 transistor. This final link in the chain is what ultimately completes the coil's path to ground, causing the 28 volt coil to energize momentarily.

As I can't find a schematic... do you know which of the 7408/7402 chips run this bumper? is that the same as the IC2 you suspect? I can change the PIA, the 7402/7408 chip, and the 2n4401 (I know which TIP122 is the correct one) I assume the 2n4401 is the one next to the TIP122..

That just leaves the PIA and 7402/7408 chip to find...

Steve

Yup, IC2 is the 7408/7402 chip mentioned. Actually, IC2 is a 7408. IC2 is it's location....kinda like video game chip locations..a la B12 or C5. This is the same, except Williams gave them number locations...IC1, IC2, IC3, etc.

If you're gonna do the shotgun approach, I'd do IC2 first, and test...before trying to pull the PIA. You can use this to find IC2 (if your board isn't screened with part locations)...it's hard to read....left hand side...towards the middle.
http://www.pinrepair.com/sys37/s6drive1.pdf

Edward

 

[Leinhit]

excellent.. you gave me another step to try.. I will and report back..

will find a replacement and order it...

tks...