James’ Blog

Classic 8-Driver problem… or not.

Posted on March 8th, 2007 by James.
Categories: Pinball.

When my divertor coil melted I assumed that I had the classic 8 driver problem of the TIP102 transistors failing on the 8 driver board.

At the time I took off my 8 driver and removed the transistor for the coil that turned to mush and tested it.. it was totally fuct (that’s “Function Use Completely Terminated” 😉 ).

TIP102 transistors are really rare. There’s a moderately equivalent part that you can get from Maplin, but it’s not as good, so I decided to rummage around the internet a bit more.

After nearly a week I finally found some on ebay going cheap and stuck in a bid.. a few days later a very very nice guy called Jeff replied to a message I’d posted on the yahoo ukpinball forum and said he’d send me some TIP122’s (pretty much the same thing) for free from his stash in the US. So now I’ve got about 10 of them and I only needed two! 🙂 If anyone wants one let me know!

Looking at the shoddy soldering job in the pic above it’s not hard to see why this thing blew. The soldering is crap (no acronym this time! 😉 ) and the TIP102s were actually the dodgyish Maplin replacements! So I’m really glad I didn’t get them!

After a bit of cleaning up, I stuck in my shiny new TIP102s

Much much better! 🙂 So.. this is where it gets interesting.. I stuck my new 8 driver in and being the cautious fellow that I am, powered on my pinball with the high voltage disconnected (coin door open) and the playfield up so I could monitor my divertors. As soon as I engaged the high voltage, one of my divertors locked on full power! Eep! So I immediately turned everything off and checked my soldering.. everything was spot on.. no gaps accidentally crossed with stray solder.. everything working correctly. Bizarre.. plugged everything back in .. same problem.

For some reason I decided to remove the ribbon cable from the 8 driver to see what that did.. it stopped the coil locking. Put it back on.. locks. Then I removed the ribbon cable completely and cleaned it a bit and reseated it on the CPU board and the 8 driver.. now everything works perfectly! I’ve never heard of the ribbon cable causing this problem before. Quite strange.. but it’s working now, so no complaints from me! 🙂

I bought a new bridge rectifier from pinball heaven a while back in case it was my BR3 causing this problem, but it doesn’t looks like it is. I think I’m going to change it anyway just to be on the safe side, but that’s some fun for another day 🙂

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