It looks like a pull down resistor. I would guess that resistor will prevent your coin lock out relay from staying de-energized, but it might be able to momentarily de-energize. What switches are on the coin lock out relay?

I agree that it should have no effect.

I'm an electronics guy and a lot of this AC stuff is fuzzy for me, but it still looks like a pulldown resistor to me. In other words, if the switch on the score motor failed, the coil would energize through this resistor, but it would do it comparatively slowly.

If that's the case the better question might be, is there a reason the coin lockout relay might need to fail safe?

I'm not sure what we're missing. The only other purpose I can think of would be to provide a warming current to ensure a fast response of the relay, but I can't think why you would want that either.

I don't understand that one either. But I know this much, pinball manufacturers are (and were) notoriously cheap. If it didn't need to be there for something, it wouldn't be there. Maybe compensating for some design flaw in that particular game? Who knows?

Could it be to balance the voltage across the two other "resistors" the coin lock out and the lock 105 ohm? Cause they will have a different voltage drop and current but maybe putting this in parallel somehow changes that a bit.

I may be wanting to say balance the current... but its been a while since I had physics/electronics.

Chris,
Have you posted this on the yahoo EM group?
http://games.groups.yahoo.com/group/empinbalmachines/

there is a broader EM audience there .

--Jeff

Maybe I am repeating what you said... But if the make break normally closed switch is opened that resistor would allow some current to flow through the the coin lock out relay acting as an in series circuit with the lock out coil... but I thought that make break switch that is normally closed was attached to a continuous duty coil so its only really off if the game is off... right... so I don't get what it does when that switch is closed. Then it kind seems pointless as the current would just go around it so its not like it would be modifying anything to the left in that diagram...

I think you should just take it out and see if you notice anything change. I don't see how anything could break that way.

chrisbee I think that resistor just drops the voltage to the score motor switches
if you measure the voltage before the resistor and after I think it's dropping the voltage

just a thought
tom

Dear Chrisbee and other participants
Doing time I read in http://www.pinrepair.com/em/index.htm and http://www.pinwiki.com/wiki/index.php?title=EM_Repair Here I looked at different forms of switches -> 4.3.4 Make-Make aka Form AA switch -> Additional information & photos about leaf switches can be found here. So I clicked on the word "here" -> http://bingo.cdyn.com/techno/readschem/switches.html , looking around -> http://bingo.cdyn.com/techno/readschem/resistor.html
AND IN THAT ARTICLE, Case 2, they offer an interesting theorie on "Coin Lockout coil and resistor": To hinder 2 players on "rapidly to throw 2 coins in" -> (FIRST coin - please wait - SECOND coin).

I am helping in a german forum on "Bally Space Time": http://www.ipdb.org/machine.cgi?id=2262 - the "Coin Lockout Coil and resistor (8200 Ohm, 1/2 Watt)" is in the schema (C.5--9.2).
AND: An resistor (3300 Ohm, 2 Watt) is (rougly H-6) with "Switch on Tunnel-Relay - Flash Motor - Flash-Release-Coil" F.0-to-J.4---5.4.
AND: An resistor (70 Ohm) is with "Tunnel-Relay", F.0---9.0
AND: resistors (70 Ohm) are with "Extra-Ball-Target-Relay, Start-Tunnel-Target-Relay" around F---19

I do not have Bally-Pins - will an owner try out: "playing an hour" with "Coin Lockout Coil WITH resistor mounted" -> "Heat of Coil" ? , "Sparks on Score Motor" ? "Timing of Coil-movement" ?
Afterwards the same, but the resistor un-soldered ?

I like that "bingo.cdyn" article. Greetings Rolf

The lockout coil is a "Continuous Duty" Coil but needs to be de-energized at times, (rejecting a coin when inserted while the score motor has already begun turning). It is NOT in series with the lockout relay. The purpose of the resistor is to maintain some power to the coil even when it needs to be de-energized.

Correction - Not in series with the Lock Relay.

That resistor absorbs some of the back-EMF generated when the switch opens. It prevents or limits arcing on the switch.

I wasn't sure of this when the original RGP thread was active, but I found a reference to it in the Gottlieb service manual.

- Kerry

P.S. Long time listener, first time poster

Great to hear from you Kerry. You schooled and helped me out a TON on RGP in the early days of my EM learning curve!

Cheers,
Frank

Good to see you post on Pinside Kerry.

Thanks again for the help you gave me on RGP in years past.

Ken

For those interested, the resistor is described in the "D. Gottlieb & Co. Instruction and Service Manual", a helpful little paperback. You can find it here: http://www.crowriver.com/books/bk079.htm

Page 37: "Resistors are used across the rivets of some step switches that are powering relays. The application of the resistor cuts down the arcing and pitting on the rivets on the step switch."

This would be true for other types of switches also.
And... thanks for the kind words.

Same resistor is usually found behind the 0-9 unit for the alternating relay. Maintaining some power to the coil will minimize arching to the switch or rivets.