diagnosing all those problems...

[Belbtech]

Original Message:

Hey, I assume you are belbenchtech because everything I look up about this user has your name associated with it.
I wrote tacman a message on accident that I guess was intended for you instead.
The message was...

I was reading your fortune II trouble shooting information and wondering how you went about diagnosing all those problems and figureing out which chips to replace to fix the problem. I replyed to your post with all my problems but I'd really like to figure it out for myself if possible, i just need some help getting started on some testing.

Any help would be appreciated.

Thanks

Josh


Hi Josh,

I'm not sure I can explain in a short note how to troubleshoot a machine/board when it took me two years just to learn the basics of electronics...but I'll try...If you haven't had any basic electronics courses, I'm probably wasting my time & yours, too!

If you expect to troubleshoot to the component level you'll NEED schematics for the board(s) you intend to troubleshoot.  A schematic is your "road map" with the multi-layer boards on the market today this the only way you can actually tell what components are in any part of a circuit you need to troubleshoot...When I first started repairing electronic boards most boards were either single or two sided boards and you could follow a trace from component to component just by using your eyes, and you could basically reverse engineer most boards.  Besides a schematic you'll need a data sheet for each component you'll encounter in the problem circuit, it's impossible to follow a circuit on a problem board without knowing the internal workings of the ICs in the circuit.  A good schematic will have test points for voltages & waveforms that should be checked.

After you have acquired a schematic and all the data sheets for the ICs you'll encounter in the circuit, what you need to do is be aware of what the machine/board is doing or is not doing...usually it is either doing something it isn't suppose to do (i.e. strange colors on a monitor, door open error, etc...) or something it is suppose to do and it isn't (cashout button is pushed and nothing happens...).  You wouldn't want to troubleshoot a machine's inputs if you have problems with the monitor colors being wrong...

Once you have the problem narrowed down to one circuit you need to figure where the information (signal) is being lost (or distorted)...the easiest & fastest way is to divide & conquer, look for the signal half way through the problem circuit...if it is present you need to go half way through the rest of the circuit, if present repeat the process, until the signal is lost, then back up one component etc...until the signal is found again...replace the component where the signal is lost.
If you don't have the signal at the first check of the problem circuit you need to reverse the process and divide the circuit by half from you starting point and check for the signal, if not found you need to divide in half again until the signal is found & then go component by component until the signal is lost again, when lost replace the component where the signal disappeared...

Of course you could just change all the electrolytic capacitors &/or shotgun the general area...sometimes a person can get "lucky"...

Hope some of this helped...

Good luck & God bless,
Mike><>

[StatFreak]

I don't know if it helped Josh (I hope it did) but it's a good, concise plan of attack for us budding amateur sleuths trying to fix our own machines.

Thanks Mike. K+

P.S. We miss your posts!