(Topic ID: 322631)

TAF Switch Column 3 dead, replaced U20 multiple times

By RandyW

2 days ago



Topic Stats

  • 8 posts
  • 5 Pinsiders participating
  • Latest reply 2 days ago by Miguel351
  • No one calls this topic a favorite

You

Linked Games

#1 2 days ago

Ok, I am missing something on this one. I am finishing up a playfield swap on a TAF and column 3 of the switches are dead. They do nothing in the switch test, I cannot trigger them with jumpers and a Diode, and I seem to have continuity all the way through the switch circuit. So I assume U20 is dead, right?

I bought a bunch of the chips a while back and have put no less than 5 in, with none of them bringing the switch column back to life. So surely I do not have a bag full of U20's that are all dead in the exact same way, Right? What am I missing here? The MPU is a new aftermarket unit from Rottendog.

#2 2 days ago

If you have the switch wiring removed, and you can't trigger it on the connectors themselves, AND because you've tried other u20's.... look for a short or missing connection between the connector and the rest of the board.

#3 2 days ago

Yes to the above. Stop replacing the chip! First try to trigger one of the switches by shorting the appropriate two connector pins on the board with the connectors removed. If you show the correct switch closure in switch test, you have a wiring problem/break between the connector and the playfield. If no switch closure shows, something on the board or its molex pin is bad. Get a meter and start checking continuity from the pin back to the chip.

#4 2 days ago

Since the original MPU does not have U20 already in an IC socket, did you ohm out the traces to be sure no damage was done to the board once you removed it?

#5 2 days ago
Quoted from PinballManiac40:

Since the original MPU does not have U20 already in an IC socket, did you ohm out the traces to be sure no damage was done to the board once you removed it?

It's a rottendog

#6 2 days ago

Barf dog

Have the original MPU available to put in?

#7 2 days ago

I have another MPU from Andrew at NVRAM.Weebly that I will toss into it next week, see if that solves the issue.

#8 2 days ago
Quoted from sbmania:

Yes to the above. Stop replacing the chip! First try to trigger one of the switches by shorting the appropriate two connector pins on the board with the connectors removed. If you show the correct switch closure in switch test, you have a wiring problem/break between the connector and the playfield. If no switch closure shows, something on the board or its molex pin is bad. Get a meter and start checking continuity from the pin back to the chip.

This. Could also be a poor connection in the IDC connector on the board.

Promoted items from the Pinside Marketplace
$ 9.95
Eproms
Pinballrom
Wanted
Machine - Wanted
Macomb, MI
$ 11.00
13,000
Machine - For Sale
Lake Elsinore, CA

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, become a Pinside+ member!