pin board repair

[Op-Bell]

Reed relays have a bad habit of getting welded shut if you use them for inductive loads. They're really designed for small signals like your voice in a telephone exchange, not for power switching. To make matters worse, reed relays are extremely fast. It could have been opening and closing the circuit 120 times a second, arcing away like the light on the Luxor inside the coil where you couldn't see it. So yeah, you should hook it up with diodes, and since reed relays are very low inductance you might also need a capacitor across the coil, say about 22uF 16V, positive to the diode stripes. That would be to stop the reed buzzing and arcing. There's not much you can do to protect the contacts, but putting a 0.1uF 250V capacitor across might help save them. (Yes, I mean 250V).

[stayouttadabunker]

From what you're saying...
it seems that the reason why the playfield bulb got brighter is because
the coil was dumping the magnetic energy out and saw a way out by the bulb...
so the bulb got really bright.
I had some action going on under there! 

Okay,  Instead of putting a cap on it,
what size/type relay and diode would you suggest for this modification/application?
The bottom one is the SPST 5Vdc relay I tried. (I think the coil got welded closed)
The top one (24VAC) doesn't "close" when the 6Vdc from the playfield bulb was applied to it>>>

[Op-Bell]

From what you're saying...
it seems that the reason why the playfield got brighter is because the coil was dumping the magnetic energy out and saw a way by the bulb... so the bulb got really bright.

I don't know - it bothers me that you said the light got really dim first. That shouldn't have happened. Then when it was bright, as long as the light was on, ie getting power, so was the relay coil, so there was no energy being dumped. I'd be inclined to check the wiring rather carefully and inspect the relay with an ohm meter, in case the 12V was somehow making it to the coil contacts and the lamp.

As long as you need to shop for parts, I'd suggest you go solid state with a triac. That would be cheaper than a relay and put no load on the lamp driver, and triacs are particularly made for switching AC power. Anyone who can sell you a triac will be able to advise you on the right kind.

[stayouttadabunker]

Those dummies at Radio Shack in my town have triacs in the shelving cabinet,
but I'll probably have to show them what a triac is... Arghhh!
I know for sure they won't be able to help me....

I want to point out that my bulb ("LAMP" in your drawing) is 6 VDC
but the drawing is showing the bottom line connected to the 12Vac...
should it be like that?

[Op-Bell]

With a triac, there has to be one pin common between the gate driver and the load. There may already be a common connection between the 12VAC and 6V ground, and if so, connect as above. If there's no connection between 12V and 6V, you have the choice of which side to use. I should point out that although I've never closely examined a pinball PCB, I'm almost certain that all the AC coil drivers will be triacs, not transistors, therefore there will probably be a common between the AC circuit and the board supply. Note, however, nothing says that common has to be 0V!!!!! You may find one side of the AC supply is tied to +12, +24, or whatever voltages are present up there. Probe carefully before connecting!

Sod's Law, triac corollary: "If you put a fuse in series with a triac, the triac will blow first and protect the fuse".  

[Foster]

Sod's Law, triac corollary: "If you put a fuse in series with a triac, the triac will blow first and protect the fuse".  

I ddint realize that would actually happen.

[Op-Bell]

Or, you can use a solid state relay! Those are essentially an opto-isolator and a triac in one package. You drive them like turning on an LED, and the other side switches AC with no common connection to the DC.

As it happens, there's a little group of suitable solid state relays right in the middle of every IGT S+ board. Skinny packages about 1 inch long, 1/8 inch thick, 1/4 inch high, with four pins in a line.

[stayouttadabunker]

Or, you can use a solid state relay! Those are essentially an opto-isolator and a triac in one package. You drive them like turning on an LED, and the other side switches AC with no common connection to the DC.

As it happens, there's a little group of suitable solid state relays right in the middle of every IGT S+ board. Skinny packages about 1 inch long, 1/8 inch thick, 1/4 inch high, with four pins in a line.

Oh, that's cool...
I have a few junk old S+ boards too!
I will try to locate them later today and
see if I can find the relay package you've mentioned...
Thank you  so much for your help on this guys!
I am learning so much about electronic circuitry it's unbeleivable!

[dogwrangler]

Ah yes, system grounds....  I had some excitement many years ago when I was debugging a kluged video board driving a old tv converted to a monitor.  Turns out the old tv did not have an isolation transformer and its ground was much (much) different than my scope ground.  Had 120v zip through the video board and it was never heard from again.  But at least I didn't fry the scope.  So I agree, just because it says Gnd, or you think it should be Gnd, doesn't mean it's not 120v away from "your ground".  A check with a volt meter (both ac and dc!) should help out.

Cheers,
-Greg

(and then there is the time pulling 120v from two separate outlets and how I learned about three phase power... but that's a different story)

[stayouttadabunker]

haha!...
Is that when you saw the intensity of blue light?

[BJones]

I wasn't tying to offend you in any way;  I think you took what I said as a bit harsh and it was not intended in that manner.  Of course the pin is yours and yes you are free to do with it whatever you want.  That said, good luck with your modifications.

A lot of old pinballs are neglected and found in barns or areas that cause them to corrode and rust up.  It really is sad.  I've picked up quite a few pinballs that were neglected and the owners just didn't know what to do with them.  As long as the glass is on, the playfield should be decently protected. 

For some reason, Sterns from that era have corrosion problems on all of the underside metal parts.  I am assuming that the steel they used was cheaper.  To help out a bit on this, I've used a berry's tumbler and left the metal parts that will fit in there for a day or two.  They come out very shiny.  I would suggest you do this with the metal plungers on all of the coils as they rust up decently in old Sterns, even in indoor settings.  Doing so speeds up the plunger as it reduces the friction and makes your game really pop and play much better.  It really makes a difference in the slingshots and flippers.

Clay's guide at marvins is a killer resource.  You definately started right by reading it.  Good luck with your game!

[stayouttadabunker]

oh crappers,
I'm so sorry if I came off looking that way- I didn't mean to and was not offended.
I'm a lousy writer and don't convey my thoughts on paper as well as I wish.
Please forgive me...I welcome all constructive criticism or thoughts on anything I do...
I believe it's very good to see or hear other viewpoints on something!
That is why this forum is such a great place to be part of...
no matter what anyone says or does, someone else has different ideas.
And thank you so much for the part about the rusty solenoid plungers...
I WILL take a look at it because I noticed yesterday that the left flipper was sticking! LOL
I got a brand new tempered glass ( $38.00 locally) in today and installed it...
my wife thinks it looks so good now - she said she can actually see the ball moving around now! 

You are right on the money about that marvin's site...it IS very helpful!

[stayouttadabunker]

Or, you can use a solid state relay! Those are essentially an opto-isolator and a triac in one package. You drive them like turning on an LED, and the other side switches AC with no common connection to the DC.

As it happens, there's a little group of suitable solid state relays right in the middle of every IGT S+ board. Skinny packages about 1 inch long, 1/8 inch thick, 1/4 inch high, with four pins in a line.

Would you be thinking of the (Opto, Coupler, Darl, 6N139 ) components at positions U20/U28/U29?
I'm referring to the 10MHz MPU Processor Board 755-057-00 from the IGT Service & Parts Manual   Section 5 - Page 122.

ADD>>>
I think I've located them...
Components at locations K1-K8 ( RELAY, SSR, 120VAC 1A, SIP 4-pin )
Thank you very much for leading me in the right direction!

[Op-Bell]

K1 to K8, that is right. Various part numbers, PS1200, SP1201, PS1210. They're so old I can't find a data sheet on them but they were made by International Rectifier originally. The 6N139s are also opto triacs, 120V but very low current, and Q1 to Q16 are triacs not transistors. They have a T on them for the manufacturer, Teccor.

[stayouttadabunker]

Well,
I tried the 4-pin SSR from an old S+ MPU board.
I was able to get it to turn on and "close" the 12VAC line but
it wouldn't shut off ("open") unless I un-soldered the 6VDC input for the "coil".
I tried to solder a capacitor in different positions in an effort to drain off the excess power -
to "unstick" the "coil" but no luck - unless, I tried this>>>

When I touch the capacitor about 3 times to the other side of the of the relay
(Which controls the opening and closing of the positive 12VAC line) - the relay "opens" and turns off finally.
But I have to do this manually in order to turn it off...

I know I'm real close to solving this but I'm missing one step somewhere?

[Op-Bell]

Thinking about this, there's probably a resistor supplying a small current constantly to keep the lamp filament warm. This makes the lamps last much longer, as it's the large current when they switch on cold that usually burns them out. That's consistent with why, when you touch the capacitor, the relay drops out - for a moment the cap looks like a short circuit and takes all the current.

It may be difficult to get round this. A solid state relay only needs a small current. A "real" relay with a spacer to stop the armature actually touching the coil may work.

[stayouttadabunker]

Okay,
I took the cover off of this particular 6VDC coil relay and exposed it's inner workings.
(by the way, it only needs about 4.3 VDC to pull the armature against the coil)
I then put a strip of paper between the armature and the coil head.
When I gave the coil about 4.3VDC for about 2 seconds, I turned off the 4.3VDC.
The coil still remained energized and pressed the armature tightly against the paper.
I had to release the energized coil's power by touching the coil's contacts with a 250V 1.0K capacitor.
The coil then released the armature.

I tried it again, but this time with 2 pieces of paper sandwiched between the armature and the coil head.
I powered up the coil again with the 4.3VDC for about 2 seconds then turned off the 4.3VDC.
The coil again remained energized and was now pressed tightly against 2 pieces of paper.
Again, I touched the coil contacts with the capacitor and the coil released.

It seems that whenever I turn off the 4.3VDC power to the coil,
the coil remains energized even though the armature is NOT physically touching the coil's head.

Another scenario I tried later on...>>>
If I solder the capacitor to the coils contacts, the 4.3VDC doesn't energize the coil at all.
Instead, the 4.3VDC probably runs into the capacitor somehow and
charges it up- instead of going to the coil.

Yet another scenario I tried>>>
Also, if I reverse the polarity with the 4.3VDC power to the coil contacts,
the coil still energizes but doesn't "pull" the armature-
I suspect it magnetic properties of the coil is now trying to "Push"away the armature,
instead of "pulling"...

I will try another type of relay...
this time a small package SSR relay - like the ones on S+ boards

[stayouttadabunker]

Still playing with the 6VDC relay...
I learned something new...
After powering up the coil again with 4.3VDC for a couple of seconds,
I removed the power to find that the coil was still energized like before.
But, this time I shorted the coil contacts with a short piece of wire instead of a capacitor...
With the plain wire touching the coil contacts, the coil immediately releases...Hmm...
Now, the plain wire is taking all the current?

I also tried to measure the voltage on the coil when it's "stuck"...
I get a 4.3VDC - 4.8 or 4.9VDC when the coil is energized.
As soon as I touch the coil contacts with a piece of wire,
the multimeter goes from 4.xVDC to zero and the coil releases the armature.

It's almost like I need a relay to shut off a relay...LOL
but that would be an endless cycle....LOL

[dogwrangler]

Hmm..  If I had to guess, the relay is some form of locking version and staying energized (getting power) from the switch side (armature).  When you short with a wire, the current locking the relay goes through the wire instead, de-energizing the relay and opening the circuit.  If it didn't the wire would blow like a fuse (hopefully not in your hand).  I would also guess there is a built in protection diode which is the reason you can't run the current in the other direction.  All the current just goes through the diode instead of the relay, and the relay never turns on.

[stayouttadabunker]

Well,
After days of fooling around with this idea of hooking up
an emergency ambulance light to the "Shoot Again" light...
I am pleased to announce that it was a success!!!

Credit and kudos goes to all those that tried to help me!!!
I especially give a warm thank you to Op-Bell (who got my brain out of the gutter )
and gave me a telephone call (From where on earth I don't know...LOL)
at home while I was tinkering with this baby!!

I soldered (in series) to the positive wire of the "Shoot Again" bulb -
A 5VDC regulator to the 6VDC+ relay coil.
I also did a lot of reading on diodes and how they can protect
board components from "power spikes" due to the coil trying to retain the current.
I soldered in a 1N4002 diode with the striped side of the diode
onto the negative side of the coil...while the other side of the diode attched to the positive side of the coil.
When the coil is energized with the "Shoot Again" light, the ambulance light comes on!
When the ball goes in the gutter - the strobe light shuts off!
EXACTLY what I was trying to do with this application!!!!
Somehow, the diode, combined with the regulated 5VDC regulator -
disperses the current in the coil and reopens the circuit-
effectively shutting off the power to the ambulance light!

Now, with this in mind...what the heck did I do?  

Now, if I can do this - I have another project in mind which will knock your socks off...
As I was playing the game trying to knock down the targets to get the ambulance light going,
I came up with an idea...
How about when you get a "Free Game" -
and in keeping with the "theme" of the game (Stern "Stars") the stars in the backlit board.... "twinkle"?

[CaptainHappy]

Mark,

  OK VIDEO is more appropriate, but we gotta work with the smileys that we have!!!

Mark (Just in case you did not know that I too am a Mark!  CH ) Stat will reward me for using his new smileys!

[StatFreak]

Mark,

  OK VIDEO is more appropriate, but we gotta work with the smileys that we have!!!

Mark (Just in case you did not know that I too am a Mark!  CH ) Stat will reward me for using his new smileys!

You want video? I'll make one!    In the web, I found only one GIF that requested pictures and it was far too large for our purposes. I made on a site that lets the user type in their desired text. I also made one that reads "We Need Pictures!", but decided to go with this one instead.

Now Mark will reciprocate and reward me as well for using his new smileys!    
It's the senior staff mutual admiration society.

[stayouttadabunker]

You guys are bonafide nuts....
We need a smiley of someone in a nuthouse wrapped in a straight jacket...

The cool thing that's exciting about this pinball application is
that it's basically endless as to what can be added to the enjoyment of playing the machine.
Successfully hooking up a relay to certain aspects of the game allows for other "rewards" to try to achieve.
So, while playing it, you get goosebumps knowing what's going to happen if
you keep the ball on the table long enough and keep striking certain targets to get your reward.
I actually got excited when I was close to setting off the ambulance light!
When I finally got a "free ball" and the ambulance light went on, I was jumping around and
then proceeded to lose the ball in the gutter!
Oh well, I least I had a "Free Ball" !...

[dogwrangler]

Glad you got it fixed!  Sorry I couldn't be of more help.

[stayouttadabunker]

That's okay! It was a learning experience for me...
I've been really digging electronic circuitry these days...
All input from you guys is wonderful and all helpful really!
I'm afraid my wife would want me to dig her more though....LOL
She knows I'm a nerd cool dog that's always trying to learn new tricks!

Stayed tuned for a short video clip!