1n4001-4007 are just progressively higher rated versions. I use 1n4007s for everything without a problem

1N4002.pdf

A 1N4006 has higher ratings than a 1N4004.

Just use 1N4007 for everything and you won't have any problems.

Many years ago there was a price difference but these days an 1N4001 costs the same as a 1N4007 so why bother with the lower rated parts?

Other than a lighting strike, is it even possible to exceed what a 1N4004 is rated to handle?
Considering that US games take 110v from a wall socket, even if something shorted, I can't think of a way for the voltage to get anywhere near 400v.

I changed out some of my 4004's for 4007's on my Joker Poker because I kept blowing mosfets on my NiWumph Driver board and we think it was from the coil field collapse, and the diode allowing some back EMF. So going higher might alleviate some of those issues.

Check the resistance on the coil, if it got hot it may have shorted.

Inductive kickback from coils and relays is no joke and can easily hit the kilovolt (or tens of kilovolts) range. The diode starts to conduct as the power is cut to the coil, which clamps this down to some mere tens or hundreds of volts for you, and since there's so little current generated by the collapsing field it does just fine. If you ever make the mistake of touching a solenoid or relay when it's firing, even with a diode across it you do get a pretty noticeable kick out of it.

Mostly, though, pinball machines are moving slowly (by electronic standards), and the ramp up and down when a coil or solenoid fires is slow enough that it's easily kept within the 400V rating of the 1N4004. Can be exceeded, especially if a switch goes bad on you and the coil is machine gunning pretty fast. (The faster a coil is fired, especially repetitively, the more kickback you'll see.)

BTW, this is part of the reason for suppression capacitors on switches that tell the MPU to fire a coil. It protects the diode, which is protecting the driver transistor, which is protecting the buffer transistor (by handling current it cannot), which protects the PIA (ditto), which protects the MCU (and so on, and so forth.)

He didn't buy either of the diodes, the first came with the game and the second one came with the replacement coil (like usual), I would easily assume - not his fault but rather the supplier or coil manufacturer

Not being familiar with this particular game, it is typical to constantly have power to the coil during a game and testing. The driver works by connecting the other end to ground.

If the coil is locking on and its a new driver / burning through divers you should start looking upstream. My first pin many years ago (F14) had locked on and burnt drivers that were locked on by their upstream drivers (a smaller transistors that allowed the controller chip to double up the number of solonoids controlled) and ultimately the controller chip was toast.

It could also be that you have a trace shorted somewhere in that area that is holding the driver on.

Either way I would disconnect the coil completely and on the non-power side (this is the wire that goes to your driver) check for continuity to ground. If grounded check again at the driver to rule out a wiring short. If grounded its time to start checking upwards, and if the coil was locked on for any period of time its also probably a good idea to re-replace that driver while you're at it.

Oh, and I use 1N4004's for just about everything. I generally like the thought of a higher rated part is better but the 4's hold up perfectly fine for decades. I'm much more likely to kill a driver with a burnt coil or by doiing something stupid than I am by having a 4 open up on me.

Sorry I probably burried it in my last post. Yes, it is normal to have constant power to all coils (and flahers). The driver operates by completing the circuit to ground.

Normal, this is how solenoids work in the pinball world. Transistor switches complete the ground path. Here's a simplified drawing.

More on Gottlieb repair http://www.pinrepair.com/sys3/

bsoledraw3 (resized).jpg

When you say "across them", do you mean each lead of your meter on each side of the coil (to each terminal)? Typically, coil supply voltage is measured meter on DC, and negative (black) lead to a suitable ground. Putting the red lead on either terminal of the coil should read the supply voltage. If you measure across, with a lead on both terminals simultaneously you will be measuring voltage drop. In this type of measurement, you'll only get a voltage reading when the coil is fired.

I was also trying to look at specifics relating to your game, but have not located a schematic online.

Normally there is a computer chip in circuit before the transistor, it is possible for it to be blown as well. The Simpsons Pinballs are bad about blowing this chip with the transistor. Be sure and add a socket for the chip for easier changing in the future.

When a coil's magnetic field collapses and the voltage is tens of kilovolts, and the PIV rating of a 1N4004 is 400V, then one would assume machines everywhere would be failing. The purpose of the diode is to conduct CURRENT in the FORWARD direction to shunt the spike to ground. The rating you are concerned with is not PIV (which is the reverse direction voltage rating)...the spec to look at is called non-repetitive peak forward surge current. This spec is max 30 amps for all 1N series diodes. A 1N4004 standard diode is plenty sufficient.

yeah, I still fuzzy on what you're doing here. But I'm not done helping yet. You provided a driver schematic, but we are talking about what you are measuring at the coils, so we should start there. I have a Cue Ball Wizard, which is also a Gottlieb System 3, so I can use those schematics as well to some degree, plus if I need to make measurements myself I would also be able to do that.

Can we find out by referring to solenoid numbers compared to the playboard schematic, and also where you are putting your test leads in these circuits. I just need to wrap my head around what you are getting and where.

cueball (resized).JPG

OK...what you are seeing is correct operation (and you said this is the good one) So what your measurements mean: when measuring across diode/solenoid you will see 0 volts. This is because there is no current flowing, resulting in no voltage drop. When you actuate the solenoid, you are seeing a peak voltage for a second caused by the rush of current across the resistance of the coil. If you were to measure it with your negative probe on ground and the positive probe on either tab of the coil, you would see the coil supply voltage when the the coil is static, and then a brief drop to near zero volts as the coil fires (almost exactly the opposite of what you see when measuring across.

Now in this situation, disconnecting a wire from the solenoid, you are measuring only the supply voltage. It doesn't matter if you actuate the coil or not...you've disconnected a path for the current to flow. So the only thing you have learned here is there is supply voltage present at the coil. Now you would need to reconnect the coil wire you disconnected. Then at this point, with the coil wires reconnected and supply voltage is present, you should be able to confirm that the coil fires by briefly grounding the anode side of the coil diode. From there, you would need to troubleshoot at the driver board to find out why the transistor "switch" is not completing the circuit.

Well i think the issue stated was that the coil is locking on, so the thing to measure is continuity to ground from the other wire (non power supply wire) with ground. While the coil is disconnected is ideal since its already disconnected anyway as it removes the coil and the power circuit from the equation.

Anyway, connect one lead to your ground strap and the other lead to the non powered coil wire (this is the wire that actually drives the coil by connecting to ground at the driver transistor).

Heres how to read the result:
- If grounded with game on but not grounded with game off: your transistors control circuit (upstream from the transistor) is bad and holding the transistor on.
- If always grounded: your transistor is likely fried but could be a short in wiring as well. You will need to locate the transistor in question and test there to eliminate wiring as an issue. Note that the transistors control circuit could also be bad as well but that fault through this test method is masked by the fried transistor. Replace transistor and retest before connecting to a coil again.

You can also test the transistor itself directly using info in the link to pinrepair that was given above.... But I tend to go this route as it also tests the wiring.

Finally, make sure when re-connecting the coil you connect the power wire to whatever side of the coil is oriented properly with the diode. Look at your good coils for reference. Backwards wiring here, even if everything on the board is fixed will immediately undo all of your board repairs the very first time the coil fires.

Orientation doesn't matter for operation as its basically just an electromagnet and will draw in the steel plunger regardless.

However, it is recommended that the end of the coil with the lugs be oriented away from the coil stop. This is because vibration from the plunger hitting the stop is strongest there and can over time break things loose.

So your pop bumper coils with the lugs closest to the playfield are optimally positioned, but both work.

+1 what merccat said