Gang:

I started resuscitating a Firepower that had a very hard life. Initial inspection revealed several fried coils, hacked displays, and a transformer that was completely mis-wired. I never even powered it on, but rather, immediately gutted it, reworked the cabinet, boards, and displays. I also added the additional bridge rectifiers per vid1900 's guide.

Now, it is all finally coming back together and the cabinet and head are fully reassembled. The playfield is still untouched and not in the cabinet. New groundstrap, new power cord, new fuses, all installed. Here's the issue. When I power on, I get nothing. No transformer hum, no GI at the coin door or backbox.

First thing I did was make sure all of my cabinet wiring matched my schematic (It did NOT originally).
Confirmed that I have 122VAC at the service outlet.
Confirmed that I also have 122VAC when I test across 6PI-1 and 6PI-3, when the power switch is "ON" (closed).
The input voltage wires are all at their correct lugs per the schematic (they were NOT originally and I did document their original placements, if we need that info later)

I have not connected any PCB boards yet but can add the power supply if we need to for troubleshooting. However, I was hoping to be able to validate proper voltages at the transformer. Would it not be possible to probe the wires (at the molex plug) coming from the transformer output lugs?

I have yet to be able to determine any voltage at the transformer or beyond.

Schematic and photo of transformer provided for reference - I have confirmed that the model of transformer installed is correct.

Thanks for weighing in!

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I did, (with black DMM lead to the grey white wire and red lead to either grey wire) and got no voltage reading. FWIW, the schematic reads that 9.3VAC is the correct out put there - not 18VAC, but regardless I get nothing when testing as described.

Bump for the AM crowd

Quench just to make sure I understand correctly - unplug the machine, set DMM to resistance (Ohms), place leads on the power plug, flip the power switch to "on" and see if the resistance drops?

Is this verified by simply checking for continuity from the input side of the transformer to the molex on the output? (e.g. input lug 8 to Grey wire in molex socket 16)

Quench Test completed. The drop in resistance was VERY small when the power switch was flipped to the "on" position. The photos attached are indicative of the drop and were consistent across half a dozen tests.

Any suggestions on where/what to check next?

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Quench There are no external jumpers between the transformer lugs.

For what it may be worth - I will provide a synopsis of how the transformer WAS wired when I inherited it.

The YLW wire WAS connected to lug 5, but per the schematic it should be on lug 1 (current location)
The BLK/WHT wire WAS connected to lug 2, but per the schematic it should be on lug 4 (current location)
The BRN/WHT wire WAS connected to lug 1, but per the schematic it should be on lug 5 (current location)
The WHT/RED wire WAS connected to lug 6, but per the schematic it should be on lug 8 (current location)

I never attempted powering the game on when it was in its earlier state as even though the transformer was the correct part number, the wiring was clearly not aligned with the schematic.

Further more, in its original state, molex socket 6P1-1 did not provide continuity to the BLK main line as per the schematic. Neither was there continuity between 6P1-3 and the WHT line. As a result I flipped pins 1 & 3 in 6P1 and now the continuity tests read as expected from the main line all the way to 6P1-1&3.

Yes, the fuse and fuse block were both replaced and a DMM test confirms that the fuse is good.

Would testing for continuity between lugs 2 and 3 determine whether or not the jumper is internal?

6P1 is definitely correct.

I need to check 6J1. Will do that and check for internal "jumper" connectivity between transformer lugs after work.

Is there an easy way to check voltage (or even correct resistance) at the input transformer lugs (exercising caution, of course)?

Isolated the transformer. Even in the absence of jumpers, there is indeed continuity between lugs:
1&2
3&4
5&6
7&8

Resistance on lugs:
1&2 = 1.0ohms
5&6 = 1.0ohms
3&4 = 0.2ohms
7&8 = 0.2ohms

Verified all wires in 6J1 are correct.

Reconnected 6J1 and 6P1 and retested continuity. When the transformer is no longer isolated, there is then continuity between lugs:
1,2,5&6
3,4,7&8

I am guessing that the continuity points change when the transformer is no longer isolated due to the looped wires entering 6P1.

Are we any closer to being confident that the transformer is good?

Part of me wonders what would happen if I rewired the transformer to the way I found it (as described in post #10) to see what I get.

Quench There are no jumper links there now. Are you suggesting that I add them?

It's aliiiiiiiiiiiiiiiiiiiiiiiiiiiiiive!

@quench, Great call on the jumpers! It made sense, I was just having a hard time wrapping my mind around the fact that someone would have actually removed them. They were easily added and continuity verified before power up.

The game was finally powered on for the first time in at least the 3 years I have owned it - and I know it hadn't been on for a much longer period than that.

More good news is that I have correct voltages at all test points, no display issues, and was able to successfully navigate all the diagnostic menus.

You, sir, are one of the reasons why this community is still great - thank you so much for your help!

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So, spent the last few weeks rebuilding all of my coils and mechs (replacing diodes and adding molex connectors to make them modular). Successfully tested all of them and left it sitting in attract for over thirty minutes. Did this on more than one occasion. Then a couple of nights ago while sitting in attract mode smoke started pouring out of the backbox. Turns out the grey wire from lug 16 that produces the 9.3VAC got so hot that it melted the insulation on the wire.

The fuse at 6F3 did NOT blow. Any ideas as to what would cause the wire to get so hot that it would melt, yet allow the fuse to remain intact? All ideas and suggestions are welcome!

the red circle below reflects what melted.
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Quench

Here we go again! That would imply that the short is located in the backbox, then - correct?

What's weird is that the wire physically runs through the fuse card, I don't know how it could ever reach 10P1 otherwise as it is only a single line.

There is really no way to replace the (now) un-insulated wire without taking apart the transformer. Am I now in need of a replacement, or is there a "tried" method of replacing that wire exiting the transformer?

All fuses are (and have been) the correct rating. All fuses are still testing "good".

Last bit of work I did was to replace D7 on the power board as it was installed backwards (it may have been D8, but one was clearly reversed) and blowing the fuse at 6F3. I also replaced the GI pins on the molex plug/receptacle where they enter the playfield. I did have the game up and in attract several times (without blowing fuses) after that replacement.

All my diodes on the power board still test out "good".

I think I can handle replacing the wire to the transformer and imagine I should do that before doing any more trouble shooting with a naked wire in the back box.

Now, to rip out and repair the transformer. Are we pretty confident then that there is indeed a short I need to find? I will remove the fuse card and make sure it is not the culprit.

@Quench this makes sense and is what I was thinking as it relates to where the short almost MUST be.

Sadly, the raw wire touches a lot of things as everything is cramped in that area of the backbox. It may be hard to safely leave it installed and power up again. If I can isolate it without performing surgery on the transformer first, I will. To be honest, rather than have to desolder wires and remove the harness to get the transformer out, I am half tempted to just cut any soldered wires and use molex connectors to make the transformer "modular".

I will report back after performing the tests you outline above.

Here's a photo of the backside of the fuse card. There is nothing insulating it from the backbox panel. Should there be? Given the design, I don't see how the rivets would NOT make contact. Keep in mind, this game was in pieces when I got it, so I don't have a "before" photo for reference.

I procured another transformer, but there is no way I want to even test with it until the short circuit is located/resolved.

Are there any concerns with me cutting the GI wires entering the left side of the fuse card and using a molex connector join for easy transformer removal/install as I troubleshoot and repair the burnt wire?
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OK, great feedback on the molex use for a GI circuit, guys. I was worried about the amperage. Schwaggs , thanks for confirming that the .093 caps out at 14A. Looks like I will need to desolder/solder.

Holy smokes, Quench (pun intended)! There is definitely insulation behind that card. I feel like we may have found our culprit. Those photos really helped.

Now, to cut open the back side of that transformer and replace the fried wire. I'll post again once that is complete.

Update!

Geez, repairing a transformer (if you want to do it right) requires some oddball stuff that you most likely won't have laying around.

I got lucky and sourced a spare transformer for cheap and was tempted just to drop it in, but knew I would never get around to fixing the original one.

So, I removed the old transformer, cut through the paper, tape, and found the lug in question. Removed the old wire and replaced it with a color correct match.

Next up was to order insulation paper, cambric tape, and bakelite (for building the "insulation board" behind the fuse card). The bakelite had to come all the way from China as I could not seem to find it domestically.

Got it all properly rebuilt and reinstalled last night and let the game sit in attract mode for about a half hour with no issues.

Talk about a ton of money (comparatively speaking), waiting, and rework all because of a stinking piece of missing cardstock behind the fuse card!

Going to mark this one as resolved again and tip my hat one more time to Quench and Schwaggs for the help! You guys rock!

Sorry Quench I don't have any spare Bally units.