This is my first solid state machine, so I thought I'd run through a battery of tests before turning it on to make sure I don't blow anything up. I disconnected everything from the power supply board except for the power coming from the transformer. I've done a voltage tests for all the pins on the power supply board, and I'm getting some higher than specified voltages on certain pins.

The manual says that 3J3-4, 5, 6, 7, 8 and 9 (solenoids and flippers) should all read 28 volts. But my meter reports 41 volts for each of those pins. Also, 3J4-5 through 8 should read 18 volts, but they instead read at 21 volts.

It's possible that I'm testing these pins wrong, but other tests come up as they should, and I'm using the specified grounds for each of the pins that are giving me weird readings. Is there something that I could be missing to explain these higher-than-normal readings, or has a component failed somewhere?

Thanks!

UPDATE: I found a schematic online that says if 3J3-6 through 9 are "OV" (over voltage?) then fuse F2 might be blown. I used my DMM to take out and test the connectivity of that fuse and it won't beep. All the other fuses beep when taken out and tested, though. F2 is a 2.5 slow blow fuse, so maybe that's why it won't beep, but I don't think that's how they work.

The explanation for over-voltage on 3J4-5 through 8 is that F3 might be blown, but that one tests positive for connectivity when taken out and tested. So now I'm trying to figure out why that one shows 3 more volts than it should. Maybe that doesn't matter. I think 41 volts instead of 28 does, so I'm going to pick up a few 2.5A slow blow fuses from Home Depot tomorrow. We'll see where I'm at then.

We'll see what replacing the sketchy F2 fuse does for the solenoid and flipper voltages. They're reading 41 right now, with or without the fuse in the clip. In theory, replacing that fuse will drop them down to somewhere close to 28 volts.

That leaves the lamp volatge, which is reading 21 instead of 18 volts. I think you can tell what voltage the transformer is jumpered for by the pinout of the one of the power connectors to the supply board. If the wall delivers 120V, and the thing is wired for (what it says is) 117V, would that cause the 3-volt spike in the lamps?

OK, something is definitely going on. The manual I've been referring to this whole time is supposedly a wiring schematic for Williams System 6 power supplies. But this schematic's identifiers are different than the ones in the actual Gorgar manuals that I have. So let's start over. I'd start a new thread, but that's bad form.

AHEM.

I have a blue-covered Gorgar manual with a foldout diagram of all the different boards. Connector 3J3 is listed as "Solenoid Power". Pins 4 through 7 on 3J3 say +28V next to them. I'm assuming that means that when the system is powered on, those should read 28 volts, correct? If so, then something is wrong, because they're currently reading 41 volts. Every diagram in both the blue Gorgar manual and the second manual named "Solid State Flipper Maintenance Manual" say that these pins should read +28 volts. However, there's one table on page 20 of this second manual labeled "Typical Voltage Readings" that says that the "Solenoid Supply" should read 40 volts when reading from Fuse F2 to ground. That's more in line with reality, but I'm not sure which information I should relay on across both of these manuals.

The same issue applies to connector 3J4. This connector says that pins 4 through 8 on this connector should read +16V. However, the table in this second manual says that it should read +18 volts. In any case, these pins actually read 21 volts. The variation between 18 to 21 is close enough for me to write it off, but going from 16 to 21 seems like a larger jump. I have no idea what's going on.

I really don't want to turn this thing on until I can understand why these pins are reading higher voltage than listed in (some parts of) the manuals. In some cases, significantly higher voltage.

If anyone can provide any insight, then I'd really appreciate it. Thanks!

I threw caution to the wind and plugged everything in. As was my fear, the 2.5A slow-blow fuse burned out after a pass-through or two of the solenoid test. Unless I'm completely mistaken about how electricity works, I can't help but feel that those pins reading 41 volts instead of 28 is the culprit.

I'll have to start familiarizing myself with how to do a systematic troubleshooting of the solenoid circuit. Maybe it's just a single shorted wire along the chain somewhere.

OK, I've tested every solenoid in the game, and all of them read 3 - 5 Ohms of resistance. That seems like a reasonable number, though I could be wrong. I also checked to see if my transformer was high-stepped to make up for low voltage, and it's not.

To re-state the issue I'm having: There are four pins that the diagram says should read +28V. Instead, they read +41V, regardless of whatever else is attached to the power supply board.

Plugging in the connector and running the solenoid test blows the F2 fuse, but since it's slow-blow, I'm not sure which solenoid is blowing it. I don't have a lot of these fuses, and I'd rather not burn through a bunch of them if I can avoid it. Buying a circuit breaker is an option, but it'd take a few days to get here and I feel like this problem is easily solvable with your help if I were better at stating the symptoms.

Here are some relevant pictures.

Diagram.JPG
PowerSupply-547.JPG

I'm pretty much out of ideas. I'm considering pulling the capacitors and varistor out of the circuit and testing them, but I'm not sure what that would prove - unless it demonstrates that one or more of those components is offering little to no resistance. That would explain the increase in voltage, no?

OK, so I just put in another fuse and turned it on. The knocker solenoid in the cabinet energized right away. I turned the machine off right away when I saw that. I turned it on again and let it sit for a few seconds. Sure enough, the fuse blew and the coil de-energized.

Now, I'm not sure if this solenoid has always immediately energized right away like this or not. If so, then it must've stayed energized through the solenoid test I had run earlier. If not, then this is a new problem that I have introduced. In any case, it needs to be fixed.

I found that transistors Q40 and Q41 are responsible for the knocker solenoid. If turning on the machine causes this solenoid to immediately be engaged, then that probably means one or both of these transistors are in a permanently open status, which means they need to be replaced, right?

I did some quick testing, and sure enough, transistor Q41 had some weird readings. With the black lead touching the middle, one side read .5V and the other side read .1V. All of the other TIP120 transistors on the board read .5V on both sides when tested in the same way. So, I think a replacement transistor is on the menu, at the very least.

On top of that, you're saying that I should replace the 40-pin interboard connector (2P1) at the top of the board? Do you think that's going to solve my high voltage problem, or is that even a problem? It seems like it would be a problem, but I'm still new to this. Why have a rating on the schematic at all if it's OK to exceed it by almost half again?

Fortunately, it looks like someone has already done this for me. Every single connection point looks to be in good shape. No corrosion, and the tension appears to be the same in each spot.

40Pin1-883.jpg
40Pin2.jpg
40Pin3.jpg
40Pin4.jpg

You're thinking about "stepping up" the transformer to make up for low voltage (105V or 210V) from the wall. I've checked, and the transformer is wired to accept 117V (as listed on the cabinet and in the manual) as opposed to 105V or 220V. Those three voltages are the only three options available unless we want to add or remove coils to the transformer directly.

If anyone reading this has a System 6, can you do me a favor and measure the output voltage for 3J3, pins 4 though 8 with nothing else connected to the power supply board but the two power inputs?

I still haven't found a good explanation for why those pins are reading 41 volts instead of 28, like the schematic says they should be. If a solenoid is drawing power from a line it expects to be at 28 volts, then it's going to draw tons more current and blow the fuse, isn't it? could that be that why fuse F2 is slow-blow - in order to account for minor variations in voltage? If so, then a constant 46% more voltage on the line certainly can't be good, can it?

I can understand why it wouldn't be a cause for concern since the current doesn't pass through any sensitive electronics. Those pins ultimately end up delivering power to the solenoids, though. Something non-mechanical has to act as a "gate" for that power. Are those "gates" the TIP120 transistors?

I have no idea what I'm doing. I deeply regret my purchase.

Hmmm. So if current is flowing through these transistors, and the current has 41 volts of power behind it instead of 28, why wouldn't that be an issue?

When the schematic says +28V to the solenoids, is that more of a "you need at least this much voltage in order for the solenoid to fire effectively"? If so, then is the upper limit this hazy thing that nobody really pays much attention to? How high is too high?

I was poking around looking for the specs on a TPI120 NPN transistor, and it looks like the absolute max voltage rating is 60V, which seems in line with what you're saying.

I'll replace this transistor, plug everything back in and see what happens. If I'm able to turn the machine on without anything energizing, then I'll call that a small victory. The next step will be another pass through the solenoid test to see if the fuse blows again. I'm not sure how else to diagnose the problem otherwise.

Also, here's the back of my driver board. The Bad Transistor is the one I'm going to replace tonight.

Also, notice that there are a few areas with some of the green covering missing. Normally, I would think that this is bad, but it appears that the light-green areas are pretty much metal and are thus all interconnected. This is opposed to the dark-green stuff, which I assume is the non-conductive substrate. There are several spots on the board where non-messed-up light-green covering runs right into the metal on the outside of the board, so that is presumably OK, right? I'm not sure what to make of this.

DriverBoardBack.jpg

I got home and replaced the bad transistor and plugged everything back in. Powered the machine on, and the replay coil stayed blissfully unfired. I let it sit for a while with no blown fuses. Great! So I fired up the solenoid test. It ran through about one and a half times before the fuse blew. I can't tell which number it failed on because it failed during the sound check, and the fuse is slow-blow.

I replaced the fuse and powered the machine back on. The replay coil is now staying fired on power-on again and transistor Q40 is shot once more. What I believe are the Collector and Emitters are showing voltage in both directions whereas other transistors in the board aren't.

I looked closely at the replay solenoid and the only thing that looks odd to me is the diode that goes across the two leads:

photo 2.JPG

It's hard to see with the naked eye, but with the iPhone camera, it certainly looks like that diode is fried. I'd test it, but I don't know what's normal for it when it's still in series, since the voltages are all over the place no matter which leads are on which ends - and that's constant for all the diodes in all the coils on the playfield.

I'm going to replace this diode and transistor Q40 again. If that doesn't work, then I think I'm going to give up and see if anyone's interested in a non-functional Gorgar that I paid too much for.

So you did! I owe you a Coke.

I'll check the coil when I replace the diode. If I can easily slide the sleeve in and out and the wrapper doesn't look burned, then I'll stick with the diode, I think.

Gentlemen, we have made a success!

I put a new Q40 transistor in, pulled out the replay coil and ran through the solenoid test four times with no issues.
I replaced the diode on the coil and put it back into the circuit. (As a side note, I hate soldering wires to coil lugs. Is there an easy way to do it?)

After that, I ran through the solenoid test a few more times and had no more issues. So with that, I think we can call this issue resolved.

I'll be starting a new thread with some other issues I've run into, such as Gorgar only partially speaking (like only saying GOT when the ball goes into The Pit) as well as a screeching noise mixed in whenever he says SPEAKS, YOU, GOT, and ME. I also think the G in the GAR drop target doesn't always fully register when it gets hit, though it always drops down. And I need to replace a couple of the 1-2-3-4 targets, as the rivets on them broke.

But with the solenoid issue resolved, I can definitely rest a bit easier knowing there's not any kind of unsolvable failure with my game. Thanks for your help, everyone!