Re: tech- switch matrix

in article
fa83bdab-bb60-4c02-a1c3-5bbd98faed8f@xxxxxxxxxxxxxxxxxxxxxxxxxxxx, Taylor-VA
at TaylorVA72@xxxxxxxxx wrote on 11/17/08 7:19 PM:

On Nov 17, 10:08 pm, Metahugh <metah...@xxxxxxxxx> wrote:
On Nov 17, 10:01 pm, Taylor-VA <TaylorV...@xxxxxxxxx> wrote:

Nothing when grounding pin2 on u18.

If you've got the logic probe hooking that up and listening to the
outputs of that chip would be a good first step.  If they aren't being
fed anything from whatever is upstream from them then you won't get
anything on your probe.  The outputs are pins 1, 2, 13 and 14.  You do
have to connect the probe to +5v to get anything.  There should be a
+5 test point somewhere you can hook into.

Hugh

So both pin 1 and 2 of U18 tested low on the logic probe. I am going
to assume that this means U18 is fine. Should I be able to just
continue up the line of outputs until I find a different reading than
from a working row? Can I keep using 5v to test or how do you
determine whether to use 12 or 5v?


I would not assume that unless you tried connecting from the column plug to
pins 3 and 4 on J208/J209. If one of these (pin 1 or 2 of U18) flips to
high and the other does not, then either U18 is bad, D5, R55, R56, or one of
the traces is bad. It is also important to make certain that the reference
voltage is getting to pin 4. If both flip, then U18 is good and so are the
traces. On to U13 then and the input on pin 15.

.

Relevant Pages

  • Re: Tech Help Needed WPC Hurricane
    ... compare it to pin 5 and pin 6 of the same chip. ... Also, put the game into coil test, remove J127 & J129 from the driver board, ... If I unplug it from the PDB it will quit. ... I dont have a logic probe or scope. ...
    (rec.games.pinball)
  • Tech : Stumped by Bally Solenoid board
    ... I have repaired dozens of Bally and Stern Solenoid boards in the past, ... U1 pin 6 measures low with a logic probe. ... small cap, but it still does not work correctly. ...
    (rec.games.pinball)
  • Re: Tech : Stumped by Bally Solenoid board
    ... Did you verify the proper outputs from the decoder go from high to ... Q9 - decoder pin 11 ... U1 pin 6 measures low with a logic probe. ... small cap, but it still does not work correctly. ...
    (rec.games.pinball)
  • Re: Tech Help Needed WPC Hurricane
    ... I'd suggest picking up a logic probe, they are usually around 20 bucks or less and are invaluable in troubleshooting circuits. ... compare it to pin 5 and pin 6 of the same chip. ... Also, put the game into coil test, remove J127 & J129 from the driver board, ... I shut it down and removed the PDB. ...
    (rec.games.pinball)
  • Re: TECH: Galaxian - big OOPS
    ... starfield is absent. ... I've used the logic probe on the 74273 at 6M and ... find that there is no signal at pin 8. ... Galaxian board and discovered that there should, in fact, be a signal ...
    (rec.games.video.arcade.collecting)
Loading