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Title: Bad Mikohn CHAM44 boards Post by: stayouttadabunker on December 16, 2009, 02:35:14 PM I've whacked my brains over these...
I can't figure out why they don't put anything on the display panels. I 've hooked others like these up and I have a couple of known good boards but these ones are perplexing. Does anyone know how I could go about rebuilding these? Schematics of these CHAM44's would be a good start but I'm not especially hot at knowing what acceptable readings I should be getting from the components. Help! Title: Re: Bad Mikohn CHAM44 boards Post by: jay on December 16, 2009, 09:33:38 PM The one on the bottom left of the picture is missing a couple of chips.
The other two looks part complete. If you swing the two round switches does it go through any of its test patterns ? For testing....Pin 1 on each chip should give you a voltage reading. Compare against a working board... it could simply be a bad support component, in which case one or more of the chips might not be getting power. You could also check voltage at the resistors and on the SCRS, Triacs and Transistors. I am digging for something simple as you can't go much beyond this level of testing without a scope or logic probe. Title: Re: Bad Mikohn CHAM44 boards Post by: stayouttadabunker on December 17, 2009, 01:31:41 AM The pics are pretty old, I removed the chips and swapped everything
I could from known good boards but still don't get a thing. Power units, batteries...everything besides the battery that wasn't soldered to the board. I have a logic probe but all it tells me if the signal is high or low. It's rated to connect up to 18 volts. I've used it on my pinball machine because Clay gave out excellent probe readings in his marvin pinball help guide. I have not seen anything close (Probe reading-wise) on slot machine/ Mikohn boards as to what Clay put out on pinball boards. |