MM-4 Push Buttons won't latch in

[nobbsy]

Hi All,

My MM-4 all of a sudden has stopped allowing me to make a selection.

When turning the machine on, the carousel no longer does the usual scan. The lights come on and that is it. Although I can manually scan with service switch.

Also, when attempting to make a selection, the push buttons will not latch in and I am unable to make the selection.

Does this sound familiar to anyone who may possibly point me in the right direction for my troubleshooting?

Thanks a lot
Ben

[Ron Rich]

Hi Ben,
MY GUESS, would be the 25 vac fuse, has opened ? Ron Rich

[nobbsy]

Hi Ron,

Thanks a lot for your reply. I've gone through all of the fuses and they are fine. I have a really bad version of the service manual on pdf so it's a struggle to work out where to start (the pages are all out of order haha). I guess it's a matter of starting some point-to-points and seeing where the circuit's failing.

Thanks again,
Ben

[Ron Rich]

Hi
Ben,
Didja read the "Hi Newbies" post in our FAQ's section as requested ? Ron Rich

[nobbsy]

Hi Ron,

Looks like you're on the wrong MM-4 post. I found my issue btw.

I was going through the credit unit and bumped the wiper assembly ever so slightly while testing the fuse. It made an audible click and rotated to the right (not even a whole position I don't think). Although it was now evident that the blades on the wiper were touching the contacts properly.

I haven't touched the credit controls at all so may have been a bump at some stage.

Will monitor it for now but unit is playing very nicely again.

Cheers
Ben