(Topic ID: 147686)

decipher this for me....

By boilerman

8 years ago



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  • 3 Pinsiders participating
  • Latest reply 8 years ago by boilerman
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#1 8 years ago

have an issue with a c37. it was missing the drop target complete switch. i made one, pbr did not carry this style.
this c37 had verious other hacks also. i reversed all the hacks and have everything working with the exception of this one issue.
the DT switch is in line with the 00-90 unit make/break switch and alt. relay and 2 100 PIV rectifiers and a 47 cap.
the problem is when the 0-9 make break top switch makes the light dim and the switch gets hot.
trying to trouble shoot this i burnt out the 2 diodes. i have a them to replace but my question is WHAT is this whole circuit try to accomplish ????
i looked at it 3 ways to sunday but i am not seeing it.
i know someone can answer this for me.
1st picture--make break switch 00-90 unit
2nd picture -- DT switch
3rd picture diodes ansd cap
4th picture schematic

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#2 8 years ago

The capacitor is for powering the Alternating relay. I think in this application it's serving to 'debounce' the signal, so the relay can stay energized while the pair of switches settle their state, and perhaps also rectifying the AC signal to DC (although I've not researched that, but that's what rectifiers generally do).

The "Drop Target Sw." is the make/break you fabbed/replaced. It changes state when all four targets are down (C37 has two of these, as there's another 'drop target sequence completed' switch on the schematic, which is the one in the center of the target bank).

The diodes are there to only allow current to flow in on direction (towards the Alternating relay). Since you say that the Drop Target switch was getting hot, I'd guess that a diode was reversed, and the current from the cap was flowing back through the switch. The wiring in your picture looks a bit funky for what's left of the diodes, especially with the twisted wires, so it's at least not how it left the factory.

Replacing the diodes is fairly straightforward, but pay particular attention to the banded side of the diode for correct orientation.

#3 8 years ago

i got it working. there was a short in the green+yellow wire. i am guessing that is why they removed that switch? maybe.
i under stand the cap to delay the bounce in the signal but why restrict the flow from backing into the green+yellow wire?
unless they worried the cap could send the charge in the wrong direction?
i don't recall this set up in any other game with a cap to buffer the signal
oh well on to the next project, williams heat wave

#4 8 years ago
Quoted from boilerman:

unless they worried the cap could send the charge in the wrong direction?

I think so.

I'd suspect this is an 'improved' version of the other capacitor-based buffer they used on other games. Those have the cap mounted on the back of a Jones plug.

#5 8 years ago
Quoted from DirtFlipper:

I think so.
I'd suspect this is an 'improved' version of the other capacitor-based buffer they used on other games. Those have the cap mounted on the back of a Jones plug.

that was gottlieb "improving a dead platform" 1977 everyone else was embracing SS

#6 8 years ago
Quoted from boilerman:

i got it working. there was a short in the green+yellow wire. i am guessing that is why they removed that switch? maybe.
i under stand the cap to delay the bounce in the signal but why restrict the flow from backing into the green+yellow wire?
unless they worried the cap could send the charge in the wrong direction?
i don't recall this set up in any other game with a cap to buffer the signal
oh well on to the next project, williams heat wave

You guys are both right on the money.

You only want the current to flow towards the alternating relay and the cap acts to help keep things energized (debounce is a great term) while the switches settle.

I would have also bet one of the diodes were reversed, but a short would definitely cause the issue.

Great stuff.

I want more of these.

This stuff is right in my wheelhouse.

Definitely shows I'm an old engineer.

Bert

#7 8 years ago
Quoted from fflint_18:

You guys are both right on the money.
You only want the current to flow towards the alternating relay and the cap acts to help keep things energized (debounce is a great term) while the switches settle.
I would have also bet one of the diodes were reversed, but a short would definitely cause the issue.
Great stuff.
I want more of these.
This stuff is right in my wheelhouse.
Definitely shows I'm an old engineer.
Bert

bert
have you talked to Chris lately? i have not seen him around here in quite some time.

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