(Topic ID: 81713)

Replacement Bally Triac


By parkway

5 years ago



Topic Stats

  • 7 posts
  • 3 Pinsiders participating
  • Latest reply 5 years ago by parkway
  • Topic is favorited by 1 Pinsider

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#1 5 years ago

Have a Mr and Mrs Pacman with a bad triac. Original triac isn't available anymore. What can I use as a replacement? I saw a few RGP threads about it, but never a definite answer. Anyone have any idea?

#2 5 years ago

Just to give people a bit more info -- these are the big, stud mounted TRIAC's rated at 16 amps, Motorola MAC38's. Tough to find replacement as it has low gate current in all four quadrants. I'd love to find a non-chinese alternate to these as well.

#3 5 years ago

Posting the part number of the obsolete Bally triac might help.

Triacs are pretty basic parts. You just need to match the package style with pins in the same layout and then high enough current capability and voltage.

Since triacs control AC the voltage ratings are usually 200v, 400v, or 600v. The current ratings are usually in amps.

#5 5 years ago

Ok thanks. Any danger of me buying one of these and hooking it up to try? Is worst case scenario that it doesn't work?

I also found an RGP post from 2010 by accident and Ken H mentions that a 2N5444 or equivalent would work (and the equiv is a lot cheaper, but needs a heat sink). I'd be willing to try these too for experiment sake as long as I don't blow anything up:

https://groups.google.com/forum/m/#!topic/rec.games.pinball/-wrauwDK8Fs

#6 5 years ago

Ken may have mentioned a 2N5444 before but the links in that google posting have been redirected to lower 4 and 8 amp parts and not 2N5444's.

The original MAC38-2 had a max gate current of 75mA.
The NTE5685 has an even higher max gate current - 100 to 150mA.

If you want to drive some real current - use something like this:
https://www.greatplainselectronics.com/proddetail.asp?prod=BTA25-600BW
This one has lower gate current than the NTE5685 but still higher than the original MAC38. And is not exactly a mechanical drop in replacement.

#7 5 years ago

Ok I'll give that a try in my Mr Mrs Pacman. Have to place an order for some other stuff anyway.

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