Hi everyone

I hope someone can help.

I have an original MM. Today the dot matrix and sound stopped working, but the machine worked. I removed the backboard to take a look. I saw that there were three old batteries in the back box, so I changed these. Now the machine is not working at all, except for the lights in the back box. Everything else seems dead. Except the usual noise when I turn it on.
Does anyone have any idea what is wrong - blown fuse perhaps and if so how do I locate the problem.

Many thanks in advance for any help.

MM

Thanks.

I don't think there was a power surge as I have it plugged into a surge protector. I have never changed the batteries and they were not leaking. I have had the machine for a few years.
I will buy a meter and check the fuses. I read an article and it basically said "....There are three applications of fuses in a pinball machine: the main power fuse (mounted in the metal box in the lower cabinet), the power supply fuses (5 volts, 12 volts, etc.) and circuit fuses (for example a string of GI lighting)...." since I have a green light on the power supply in the back box, I assume if there is a fuse attached, it's not blown. Does that mean it could be the main power fuse and if so how do I get to it?
Sorry this is all new to me.
Thanks
MM