Logic probe faq's. Any good links as related to board repair?

Thomas

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Logic probe faq's. Any good links as related to board repair?

I've been struggling with using my logic probes for a while now. I have never even hooked one of them up until this morning. Thanks to this little faq by the lawnmowerman.

http://lawnmowerman.rotheblog.com/logicprobe.html

So I am off and running kinda. It has been a bitch trying to use the probe while the board is installed in the machine. So I started a separate post on a test rig.

Anyway I have learned a little by following the faq above. I was wondering if the were other links teaching you how to troubleshoot boards with a logic probe as related to arcade machines?
 
I know there is a lot of info in the manuals but that already assumes you know what your doing. Unless you know of a manual for an arcade machine that breaks it all down?

So the link above help out a lot and I was wondering if there were other like it and not in a manual.
 
I know there is a lot of info in the manuals but that already assumes you know what your doing. Unless you know of a manual for an arcade machine that breaks it all down?

So the link above help out a lot and I was wondering if there were other like it and not in a manual.

I hear ya...
Most of the sites you find on how to utilize a logic probe will show you just that. In other words, the logic probe is a tool to allows you to analyze PCB issues but most (if not all) of the documentation will tell you how to use that tool. What you need are some sites that describe how to understand the fundamentals of microprocessor based systems and then in particular, arcade game systems.

I'm sure there are plenty of the former but prob not much of the latter.
I hope to whip one up... someday.
 
The concept for a logic probe is simple: is there activity on a line, and if not is the static state expected and at the right level.

If you have 1 gate driving several inputs and its pulsing, chances are good that its OK. If you have several gates driving a bus, then chances go down, as you cant differentiate one bad gate out of them all.

Keep in mind that the probe will also not necesarily show bus contention (when 2 or more gates drive the bus at different levels at the same time).

So, its just a tool that can help you use your knowledge of a circuit to determine where problems might be, but it is not the end all be all troubleshooting tool.

Only one instance I can think of where it will tell you for sure why a board is dead without thinking too much about it: Clock circuit. It either is pulsing or its not, but even then there are rare exceptions when you see life but its still not a good clock...
 
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