IMPORTANT: EM PLAYER SAFETY, HOME SAFETY, AND MAINTENANCE/OPERATOR SAFETY - A MEGA-SECTION - Also: ALWAYS USE A (GOOD) POWER STRIP OR (CORRECTLY WIRED) SWITCHED OUTLET!
PLEASE REMEMBER when working on these machines that there is constantly more voltage flowing through them then you can imagine. When working on these machines (especially with tests that don't require power), the machine should not only be switched off but also completely unplugged.
For instance, let us take a 1976 Gottlieb Royal Flush. (MUCH more safe and lacking of 120 volts than the machines of the middle 60's and earlier, but still filled with high voltage right next to lower (but still possibly dangerous) solenoid voltage):
WHENEVER the machine is plugged in, there is line voltage flowing through the machine. Since the service outlet needed to be live even for service when the machine was off (usually used to plug in soldering irons or work lights), this entire circuit is ALWAYS live! That not only includes the 40-year-old service outlet itself, but also an in-line fuse holder (bare metal) used in this service outlet circuit (and the main circuit, sometimes two separate ones) that has powerful line voltage flowing through it while your family sleeps in bed at 3 AM.
It also flows to one end of the power switch all the way in the front of the cabinet. This is never shut off even when the machine is "switched off". Only when you unplug the machine from the wall is when this power dissipates. If there is any faults in this 38-100 year old wiring, or if debris, such as from the very populated playfield directly above, falls onto any exposed wiring or metal (like the fuse holder(s)), it certainly has the potential to start a fire. PLEASE PLEASE PLEAAAAAAASE, be responsible.
All of my machines are on power strips. (Wired dedicated circuits in your home via light-switch also apply !if done correctly!) The machines are always switched off using these power strips, thus eliminating any HOT power (and hopefully a neutral link if it's a good one) from even touching a millimeter of the power cord let alone the internals of the machine. There are many people who rely on these old machine power switches and circuits while they sleep and it bothers me strongly. Many "experts" claim their machine is as safe as can be, and coming from another experienced collector with a large collection like myself, this claim of "expertise" is plain ignorance and a lot of it. If you cannot take the 5 seconds to switch off a power strip (which is quicker to shut off/turn on one machine let alone a whole row at once),
reduce nearly any chance of a fault from probably 5% to 0.001% (multiplies with each game left plugged in, as well), and protect you and your innocent family from any potential harm, I strongly pity you. While rough projects likely have more potential for causing harm, even the cleanest machine can drop a nut or a screw and start a fire. There are many that disagree and don't care - and to that I politely say "pull your head out of your ass!". You are never an expert if you do not utilize proper safety precautions even for unlikely events. A .5% chance of harming or killing myself and my family while I sleep is too much for me and it should be too much for you as well. Don't be LAZY! Moving on...
[WARNING!] IF YOUR LINE CORD OR HOUSE OUTLET IS WIRED INCORRECTLY, OR THE UNKEYED PLUG IS PLUGGED IN UPSIDE DOWN (ABOUT 50% OF THE TIME!!!!!), TAKE EXTREME CAUTION!
Many of the earlier line cords (which were basically low-gauge lamp cords from the factory) did not "keyed" prongs, meaning you can easily plug it in upside down. This is huge! It flips the HOT and neutral voltage and makes the HOT voltage no longer switched and sends it through the entire
120v circuit even when the machine is SWITCHED OFF! Even to the score motor switches! While you sleep at 3 AM! Let's look at that diagram again adjusted for an upside down or backwards-wired line cord:
Wow! Everything marked "DANGER" would be live with powerful 120v wall voltage regardless if the machine is switched off or not, it just needs to be plugged in. Again, most line cords supplied by the factory prior to the 3-prong era (which basically includes most EMs considering even when they started shipping with them late towards the middle of the 70's, most people cut off the third prong...)
are not keyed and do not look ANY different when plugged in upside down compared to "right side up". YOU HAVE BEEN WARNED! I suggest replacing with a full-blown 3-prong cord wired correctly, or if you're a purist, as least with a newer style extension cord which is almost always keyed with the neutral prong being bigger. (USA)
UNPLUG YOUR GAME WHEN WORKING ON IT, ESPECIALLY 120V/LINE VOLTAGE CIRCUITS! These are usually BUT NOT ALWAYS incased in rubber rather than cloth of the time, and can be picked out from wiring bunches before the full transistion to rubber-coated wiring later on in the 70's. (it was the tail end of the EM era before all of the major manufacturers finally switched over)
Did you know? The neutral prong is actually big one to the left, while the HOT is the smaller one to the right. (On correctly/traditionally oriented outlets with the third prong hole facing the floor)
Finally, as stated, machines from around 1967-1968 and earlier generally did not have toggle switches, but you could "bump" them off with a different kind of switch that disengaged a lock relay - which wasn't really "off" at all - EVEN LESS than the Royal Flush! (But could be woken up by any coin switch, start button, flipper switch, etc., it's all always live)
This is from a 1966 Williams "8 Ball", 10 years older than Royal Flush (and it really shows). A tad scary, isn't it? You can see things like all of the coin switches notated in this diagram, as well as a slew of relay switches, general switches, score motor switches/positions, among other things. Do you really want to sleep with all of this being fully or partially live?:
Grounded receptacles in homes entered the electrical code book in 1959 as an option, finally being upgraded to MANDATORY in 1965 or 1968. Since prior to this (and it still only really went into effect in homes built in or after 1965/1968 - which to this day isn't even close to all of them) not many had grounded outlets in their home,
so most pinball machines featured two-prong "lamp cords" from the factory. (Genuinely quite s***) In the event of a main line shorting to any metal, the machine would continue operating (unless creating an electrical short - which would blow a fuse inside of the machine). If anybody touched this piece of metal, such as a coin door, they would be SHOCKED with main line voltage.
Having done so, many times (more out of carelessness/stupidity rather than pinball machine faults...), it does hurt quite a bit and apparently hurts a HELL of a lot more if you're touching ground/neutral. (I haven't had the pleasure I don't think - getting shocked by just the HOT (one side of the wiring) hurts enough and razzles you pretty bad, you feel it flowing through you)
Anyways, back to the coin door. If they touched this large electrified piece of metal, they would be shocked, it would hurt, and the machine would stay on until somebody finally unplugged the damn thing.
With the new grounding system, a "field ground" wire is attached to all metal/conductive parts at risk inside/outside of an appliance (such as the coin door), and if line voltage was ever sent to them, it would travel through this field ground wire, through the power cord out of the machine, into the now-very-recognizable "third prong" hole in the outlet, safely travel through the walls of your house,
and when it hits the breaker/breaker box (less than a second in real time...) it trips the breaker and shuts off the entire circuit the machine or appliance is plugged into to prevent any damage, injuries, or even fatalities - all without causing an initial direct short to the neutral line inside of the machine. (I believe this is how early breakers/house fuse boxes would shut off/blow aside from being just overloaded, and it's pretty unlikely to occur compared to one loose wire)
While games started shipping with a 3-prong cord in the 70's, you should ensure that the third prong was not cut/ripped off to fit in a 2-prong outlet. Around 80% of the 3-prong pinball cords from the period and even into the 80's seem to be that way. (Remember, not a ton of people had them yet at the time!)
Additionally, often times this ground wire will only go to the frame of the transformer. (to kick the breaker off in the event of a transformer fault) Unfortunately, this does not include connections to metal pieces such as the coin door, lockdown bar, side-rails, and more.
Installing these yourself (even linked to the original intact wiring connected to the transformer frame in bright green) will provide safety and assurance for guests and players to your house and business.
There was a recent debate about grounding the side-rails that made it onto Pinside. Many say grounding the side rails is bad because it can complete a circuit when leaning on them with their body and working on the machine, whereas if they touched a live wire it would hurt significantly more as it flows through them into the ground wire.
For this reason, instead of both the side-rails and lockdown bar being grounded, in this group of two they grounded just the lockdown bar instead (which is usually always off when working on the machine), and when the lockdown bar was put back into place, it would touch the side rails and ground them as well without having them grounded when the machine is being serviced as the lockdown bar is not there to complete the grounding circuit (has continunity (connection), but no voltage/amps/current normally). The decision is up to you. If you don't "hard-wire" the side-rails, insure that the lockdown bar ALWAYS makes a good connection to the side-rails to extend this grounding measure to players when playing the game.
[DANGEROUS FLIPPER BUTTON SHOCKS/START BUTTON SHOCKS - OUCH! WHAT HAPPENED? (FISH PAPER DANGERS AND STINGS)
Often time switches and buttons are insulated with something called "fish paper", which is basically a non-conductive paper-like material that stops the flipper voltage and coin door voltage from traveling through the buttons, to the player's hands.
This can become worn or entirely destroyed with time and no longer block electrical connections.
- Many flipper switches are controlled by 30 or 50 volts. This is not as bad as 120 volts/line voltage but can definitely still hurt and cause physical damage or worse. With the fish paper damaged or destroyed, this voltage could flow through METAL flipper buttons.
- [WARNING] METAL START BUTTONS: All start switches are connected to a start relay, which is very often controlled by 120 VOLTS/MAIN LINE VOLTAGE. If the fish paper here degrades or goes missing (destroyed) it will send 120 VOLTS through any metal start buttons and also likely through the metal coin door. (which, if you're touching field ground, likely will hurt even worse! But also possibly save your life) Make sure the fish paper here is replaced or is in good condition!!!!!
- [WARNING] EARLY WILLIAMS FLIPPER BUTTONS - BALLY TOO?: As mentioned earlier on many games you can push the left flipper button to light up the game. On later games (from the 70's onward), this was controlled by 30 volts or 50 volts (solenoid voltage), but on earlier games, particularly Williams games, this was controlled by 120 VOLTS/MAIN LINE VOLTAGE and brought it right up to a switch controlled by the flipper button.
If the fish paper was damaged or missing (destroyed) here, you would get a very nasty shock through the flipper button, and if your hand is resting on that grounded lockdown bar and side-rail, it'll hurt pretty damn bad (but would also save your life instead if you can't let go)!
Remember that third schematic snippet I posted of the "earlier machine"? Take a look at the bottom left, the proof is in the pudding!: