Details - On the Power Supply Board (Rottendog replacement), the only unlit diagnostic LED says it's the 28VDC output. On startup, the 2.5 amp slo-blow fuse blows (F2). Foolishly/bravely, I systematically replaced the fuse with stronger ones (3, 4, 6, then 8 amp). Only the 8 amp fuse held, and everything started came to life... until the coil sleeves started melting about 30 seconds later. The board seems to have survived the experiment.

Any ideas on why too much power is being supplied? Any suggestions on actions to take?

Many thanks in advance.

#2 2 years ago

DAV

wayout440

Pinside member

Berea, OH

11y 113K 11,267 3 12

First a little theory, it is a question of how much power, but too long. All those coils expect a brief momentary pulse (the transistor driver circuit is a switch that makes a connection to ground). It's likely something in the CPU logic is "telling" the driving transistor to stay on when the power is supplied.

Reply

Wanna join the discussion? Please sign in to reply to this topic.

Hey there! Welcome to Pinside!

Donate to Pinside

Great to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, subscribe to Pinside+!

This page was printed from https://pinside.com/pinball/forum/topic/monday-night-football-f2-fuse-blows-on-startup and we tried optimising it for printing. Some page elements may have been deliberately hidden.

Scan the QR code on the left to jump to the URL this document was printed from.