Check your coin door disconnect....Sounds like it came loose. Either that or you shorted something and blew the high power fuse. Check those too.

If the coils have diodes on them, you need to get the wires back in the right spots.

If not, then check if one of the new coils is bad.

Then check fuses associated with your coils.

LTG

Hey Lloyd....how is the 'coil malfunction' DMD message in Stern's MPU derived? Does it have some type of closed loop feedback to determine that a coil didn't fire? Just curious....I seem to remember a software change that 'fixed' coil malfunction error messages, but never really knew how the MPU determined a malfunction.

There's a whole bunch of fuses on the power board in the backbox, have you checked that yet?

you might have a TIP transistor on the solenoid driver board that is bad. If you have the manual check which transistor runs that coil. If you installed the switch incorrectly you may have shorted the transistor on the driver board. But check all your fuses. I think there is one attached near the goalie motor itself if I remember correctly.

You might try removing that coil completely and trying the test again. If it goes away you either have a bad coil diode, wires mixed up or a bad transistor on the driver board.

best of luck getting it fixed.

Like erak mentioned the TIP transistor on the driver board for that coil needs to be replaced. I just had this same problem.

Also if you've changed out a coil, make sure the power wire is on the coil lug with the silver banded side of the coil diode.

You can check it for short, but if it were shorted the coil would always be on. It's unusual for a transistor to just not switch, so for now I would discount the transistor.

Take a test piece of wire, and with the game on and coin door close, touch the metal tab of the transistor in question to ground. Does the coil fire? If so, then that at least checks the power path to the coil. If the coil doesn't fire, then you've got something wrong with the power to the coil, the ground to the coil, or the coil itself. If it fires, but doesn't during game mode, then either the transistor is bad or you have a logic problem further upstream.

BTW, what do you mean, you can hear it try? If you hear the solenoid/coil trying to engage, then you likely have a bad linkage or bad sleeve...something putting the coil into a bind.

Put your meter on the lug of coil on the band side of the diode and to a convenient known ground and what do you measure in volts? Coil doesn't need to be firing. Do the same for a known working coil. Do this with power on, coin door closed. Let us know the results. I'm not too familiar with stern, but normally you should have power on the band side of the diode at all times when measured to ground. The transistor on the driver board sends ground to the coil to complete the circuit and fire the coil. If you have power on the band side of the diode, take a piece of test wire and short the other lug to ground. Coil should fire. Report results.

Okay, then the high side is okay....Very strange that grounding a ground would cause a spark and the game to reset.

Again, I'm not a Stern expert....Were this WMS/Bally/DE I'd be more comfortable.

Looking at an example schematic for WPT, I assume is something similar to Striker Extreme.

http://sternpinball.com/downloads/WPT_SGM/WPT_SEC3_CHP2.pdf

If you look at the diagram, you'll see that VDC is always on the one side (YEL-VIO), and the transistor switches the BRN-BLK to ground to complete the circuit for the coil and thus firing it. If you touched the BRN-BLK equivalent on the coil lug to ground that should be the same as the transistor switching to ground. No reason to get a reset. Spark maybe as you are completing the circuit and shunting current through the connection now, but not a reset.

Hopefully one of the Stern experts can chime in here and confirm this.

One more test if you want is to just ground the transistor tab for the coil. That should fire the coil from the transistor on. If it doesn't then something is wrong from the transistor trace to the edge connector to the coil.

Okay found this.....As I thought, the spark is normal....To avoid a reset, you should just be tapping the ground not holding it...That applies to a flipper coil as you are pulling in the high power winding. Were you by chance testing on a flipper coil? Try a vuk or something that doesn't have high power windings.

http://rgparchive-removed.com/rgpforum/showthread.php?t=344090

Okay, so the coil is good...Let's go further upstream. Find the transistor for that coil on the driver board and touch the metal top of the transistor to ground with a test wire. See if the coil fires. As a comparison do the same on a working coil/transistor combo so you know you're doing it right.

Okay....so that tells me, that the ground path is missing between the transistor and the coil.

Time to get out your DMM and put it on continuity test. Using your schematics, check continuity between the transistor ground and the connector pin for that solenoid. Do the same for the connector pin to the solenoid. Somewhere, the signal path is broke from the transistor to the coil.

Put your meter on continuity and check the metal tip of the transistor Q4 (the place where you grounded before) to the male pin 5 of the J8 connector on the board (you'll need to remove the female side of J8). You should have continuity. Then check the female side of pin 5 on J8 to the BRN-YEL on the coil. You should also have continuity here too. Let me know the results.

Though I can't be of any help, I think you 2 are doing an awesome job.

Agreed. Always good to see the helping hands getting one going again. Good luck!

Okay, examine the trace between the transistor and the male pin. Look for any breaks. Use your DMM to check for continuity on any available points along the way. You may have a cold solder joint and need to reflow the solder pads at the transistor and the connector. Reflowing means reheating the solder pads until they are liquid again and then letting them solidify. Is this a transistor you replaced? Did you orient it the correct way? Is it the correct type transistor (npn)?

With the DMM you should be able to check the metal tip to the ground leg on the transistor...then the ground leg to the solder pad. Then the solder pad to the pin. etc. Somewhere you've lost continuity.

Not sure what resistor you are referring to without a detailed schematic of SE, which I don't have. If you could post a picture, that'd be helpful. But anytime something deviates from a similar circuit, that's always suspect and I would investigate further. A resistor will have continuity across it, but not zero. It will have resistance of whatever ohms the resistor is rated at. If it is a capacitor, then it should not have continuity. If it is a diode, then you would need to check it with the meter set for diode, not resistance. Again, a picture would be helpful here, or if you have a detailed schematic of the game.

Take the board out (if you already haven't) and check continuity on the solder pads. It sounds like maybe you're checking with the board in the head. Flip the board over and you may see a bad trace, or a broken pad, or if the pad looks dull and not shiny it could be a cold solder joint. The discolored pin means the old transistor probably locked on at some point and burnt the pin before the fuse popped. That could have certainly caused the solder joint to fatigue and it needs reflowing.

It sounds like you've at least identified the area that needs attention and are close to resolving.

Yeah, your trace has lifted....Easy fix. Use a small piece of 18 gauge wire and solder between the two pads.

Something like this (not mine):

http://www.techdose.com/repairlog/Whirlwind-Pinball-Repair--CracklingMissing-Sound-Issue/387/images/soundcpu6.jpg

Nature of pinball....things break, electronics short, user error. If I remember correctly, it started when you put a diode on a coil backwards? Don't do that again

If you're immediately blowing the fuse something is shorted somewhere...I assume that the only thing you changed was adding the trace jumper? Nothing else changed from before and you could turn the machine on and the fuse didn't blow? To do the repair you took the board out....Make sure you put all the connectors back on properly and aren't off a pin on any of them. Immediately blowing even before starting a game? Adding that trace wire shouldn't have anything to do with that.

Yep, transistor, or the pre-driver transistor if there is one on this game. Probably the initial problem that burnt the trace and burnt the pin....If you read back one of my earlier posts, I think I suggested that a locked on transistor probably burnt the pin originally.

The IRL540N you had in there is really the best replacement.

The tip120 is only rated for 60V....It'll run hotter than Sh** so I wouldn't use that.

Can't use the IRF510 as it significantly more base voltage to drive the gate, and it likely won't work...I think the IRLs are logic level Mosfets and the IRFs are not.

The 3055 takes too much current to drive the base, so I doubt it would be suitable. It also is rated for 60V.

Definitely not a Tip31....It's only rated for 40V. A tip31b or c is rated for 80V and 100V.

Blew a fuse

I responded in your other thread.

Make sure your trace repair is solid...Has the ability to conduct the required current to energize the coil. As a test, ground that coil like before and see if it appears stronger than when grounded from the MPU....That'll isolate whether it is a coil problem or a MPU problem.

Just a suggestion: thrust in robertmee.

I hope you meant 'trust'!!! I don't go the other way!!!!!!!!!!!