Qbert switch input questions

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

I've got a Qbert board that's giving me problems. It seems like at least
one switch input is shorted. I've checked all the resisitors for the switch
inputs. (R1-R16, lower right corner of the main board). I've checked the
little caps next to the resistors too. A couple of them measure differently
than the others. Would the caps going "Bad" cause the switches to be
shorted on? How close do I have to be on value and type when I replace
them? Or is there an IC somewhere upstream thats suspect?

Thanks,
Matt

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

It is unlikely that the caps are causing this problem, and the variance in
the resistors is normal and not critical (unless there is a wild variance)

The following chips handle switch input:

B11 - 1 player & 2 player start buttons, coin switches, sercive switch, test
switch
B14 - joystick

If it is not your service or test switch you can go to test screen 6 and see
if any of the other inputs appear closed. If one appears stuck, you can
check the input/output pins of the 74LS240 that corresponds with that
switch. The input pins - 2, 4, 6, 8, 11, 13, 15 & 17 - should all be high
without any closed switches (remember your service switch may be on . The
output pins - 3, 5, 7, 9, 12, 14, 16 & 18 - should all be low without any
closed switches. If you are reading any thing other than that, chances are
that the 240 is bad.

-roy-

"Matt Hoy" <hoy@psys.org> wrote in message
news:1113109987.add7071982f63421b8b57dcc8cb54ed6@teranews...
> I've got a Qbert board that's giving me problems. It seems like at least
> one switch input is shorted. I've checked all the resisitors for the
> switch
> inputs. (R1-R16, lower right corner of the main board). I've checked the
> little caps next to the resistors too. A couple of them measure
> differently
> than the others. Would the caps going "Bad" cause the switches to be
> shorted on? How close do I have to be on value and type when I replace
> them? Or is there an IC somewhere upstream thats suspect?
>
> Thanks,
> Matt
>
>
>

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

Just to clarify, if the input is low without a switch closure you probably
have a wiring short.

-roy-


"Chumblespuzz" <nospam@cademo.com> wrote in message
news:Ft36e.1459$0i.1346@fe11.lga...
> It is unlikely that the caps are causing this problem, and the variance in
> the resistors is normal and not critical (unless there is a wild variance)
>
> The following chips handle switch input:
>
> B11 - 1 player & 2 player start buttons, coin switches, sercive switch,
> test switch
> B14 - joystick
>
> If it is not your service or test switch you can go to test screen 6 and
> see if any of the other inputs appear closed. If one appears stuck, you
> can check the input/output pins of the 74LS240 that corresponds with that
> switch. The input pins - 2, 4, 6, 8, 11, 13, 15 & 17 - should all be high
> without any closed switches (remember your service switch may be on .
> The output pins - 3, 5, 7, 9, 12, 14, 16 & 18 - should all be low without
> any closed switches. If you are reading any thing other than that, chances
> are that the 240 is bad.
>
> -roy-
>
> "Matt Hoy" <hoy@psys.org> wrote in message
> news:1113109987.add7071982f63421b8b57dcc8cb54ed6@teranews...
>> I've got a Qbert board that's giving me problems. It seems like at least
>> one switch input is shorted. I've checked all the resisitors for the
>> switch
>> inputs. (R1-R16, lower right corner of the main board). I've checked
>> the
>> little caps next to the resistors too. A couple of them measure
>> differently
>> than the others. Would the caps going "Bad" cause the switches to be
>> shorted on? How close do I have to be on value and type when I replace
>> them? Or is there an IC somewhere upstream thats suspect?
>>
>> Thanks,
>> Matt
>>
>>
>>
>
>

 

[Vaxx]

Archived from groups: rec.games.video.arcade.collecting (More info?)

have you checked the harness it's self??

"Matt Hoy" <hoy@psys.org> wrote in message
news:1113109987.add7071982f63421b8b57dcc8cb54ed6@teranews...
> I've got a Qbert board that's giving me problems. It seems like at least
> one switch input is shorted. I've checked all the resisitors for the
switch
> inputs. (R1-R16, lower right corner of the main board). I've checked the
> little caps next to the resistors too. A couple of them measure
differently
> than the others. Would the caps going "Bad" cause the switches to be
> shorted on? How close do I have to be on value and type when I replace
> them? Or is there an IC somewhere upstream thats suspect?
>
> Thanks,
> Matt
>
>
>