Re: Tron lives!

There are two grounds that you should check.

The grounding strap is important for grounding the control panel itself
(and also the coin door). This cuts down on static zaps.

The second issue is the switch return ground(s).

First thing is can you go into self-test mode? (on the right side of
the coin door frame). If not first thing I'd check is that J4-9 and
J4-19 are connected to ground. If you can get into it can you use the
stick to move between the settings?

Depending on the above you've got a couple of possibilities. Once I
rule out the most common stuff (bad gnd, harness is broken) my usual
strategy is:

First thing is to disconnect the inputs -- disconnect J4 and J5.

Use a scope for DMM and measure between J4-9 and J4-3(UP). Do you have
something > 4V? If not go check the resistor packs and caps. Then
short it to ground. What's on the input to the 74LS244 -- did it go to
gnd?.

If that's all looking good you could try the quick fix of replacing the
244. Or if you're inspired put a scope on the associated select (as a
trigger) and the datapin and see if it really is getting handled
correctly. i.e., check that there is activity on the trigger, and when
triggered that you're seeing the 244 present the proper values on the bus.

--Kurt

EvilJim wrote:
> Any reason to suspect the big yellow ground strap is less than
> adequate? Or is there a ground connection beyond that one?
>
> I will be looking at all of it more closely tomorrow, though IDK if
> they could have made the schems any harder to read. =)
>
> Kurt Mahan wrote:
>> First thing to check is that you have a good ground to the CP. (and to
>> the switches).
>>
>> Kurt
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Received on Tue Nov 6 21:04:14 2007