I've run into some odd voltages on my Centaur machine and, based on my rudimentary troubleshooting, it seems there's a problem with the transformer and/or its wiring.

Using both the original -54 and a brand-new replacement -54 from Anarchy, I get some really weird voltages at all TPs. All fuses are good on both boards and both boards previously would get me to GI lighting. I would appreciate direction, as many of you know way more than I do or probably ever will. Below are the various values I get with just J6 connected.

BEFORE replacing the J6 connector and terminal pins:

OLD Board | NEW Board
TP1: 0.1 VDC | TP1: 0.1 VDC
TP2: 0-2.1 VDC | TP2: 2.1 VDC
TP3: 37 VDC | TP3: 25 VDC
TP4: 70 VAC | TP4: 38-65.5 VAC
TP5: 0.0 VDC | TP5: 0.0 VDC

AFTER replacing the J6 connector and terminal pins:

NEW Board
TP1: 0.1 VDC
TP2: 12 VDC
TP3: 20.7 VDC
TP4: 92-153 VAC*
TP5: 0.0 VDC

*for TP4, I got readings of 92, 120, and 153 VAC just by bending the wiring harness this way or that.

Line voltage is 125.8 VAC (high, but within 5% tolerance), measured both at the wall and at the connector ahead of the fuse.

Based on those TP4 numbers, I'm guessing there are some cracked solders on the transformer itself. I haven't (yet) done anything with the transformer, as I'm unsure it's worth my digging around inside. Should I just go shop around for one instead? I have no problem checking this and that or doing some soldering and I can pick my way through a schematic. If someone here has a solution or a direction to lead me, I'm more than thankful.

Cheers!

@quench, I know these are pretty sturdy transformers; the only thing that has me looking toward it for the issue is that both the old and new boards come up with flaky numbers. For me, that narrows it down to either my DMM or the transformer.

I'm quite willing to buy a different DMM, if needed. The one I have is a Vici CM-2016. I have no idea if it's decent, crappy, or otherwise. I put fresh batteries in it and ran the TP checks again. I got the same results.

I've attached pics, as requested. I'm not sure they'll be of much help. As you can see, I haven't delved into the transformer at all. I've been holding back to get advice before doing anything more or deeper. I'm using the GND point on the rectifier board for my black lead. Is there somewhere better?

Should I probe the terminal pins on the J6 plug itself to see if power is coming in cleanly?

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@dothedoo, my VAC at the wall and at the connector ahead of the fuse read the same 125.8 VAC. If the power switch were bad, wouldn't I see some sort of drop at the connector?

@quench, Thanks for the reply and direction. I get 0.0 ohms when doing as you suggested. (I get 0.4 ohms by connecting my leads to confirm the DMM is actually measuring something.)

My DMM does auto-range and it was on AUTO (top-left of DMM display).

I wasn't too pleased to get a 0.0 reading. I double-checked my work and got some "interesting" results. I first tested the main fuse itself. It's definitely not blown. Then, I removed the connector from the fuse block and jumped the power wires. At first, I again got 0 but then as I gently manipulated the plug, the readings jumped all over, sometimes briefly settling in the 1.8-2.0 range. When I re-seat the connector, i can again get ~2 ohms when I push down on the white wire.

Based on all this, it seems my next (and hopefully only) step is to replace that connector and its pins. Had I not already started replacing the connectors for the rectifier board, I'd have one on hand. As it is, I'll have to order the plug and pins.
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It displays like that even on the other ranges. It just ends its auto-ranging cycle on mega-ohms. It reads like this even if I force it into other, lower ranges.

When I forcefully push the white wire down into the seated connector, the DMM ranges down and shows 2.6 ohms.

My oversight and mistake. It was 0.L when I was checking the resistance, as indicated in the pictures. My DMM likewise shows 0.L when not connected at all.

I've since discovered the (first) problem and have fixed it. IDK the term for the connector I mean other than it's the one ahead of the main fuse, carrying VAC from the wall (see pic). After looking closer at the other half of this plug, I saw one of the terminal sockets had pushed back, resulting in the flaky resistance readings. I was able to re-seat it and I'm now consistently reading 1.7 ohms on the resistance test. The transformer is humming now, too, which it wasn't before.

I have no idea how that socket loosened, since until this power issue arose, that plug hasn't been touched in the 20+ years I've owned the machine.

Is there probative value in checking the blue and brown wires from transformer to J6?

Here are the latest readings:

TP1: 8.17 VDC
TP2: 1.67 VDC
TP3: 22.67 VDC
TP4: 3.1-3.21 VAC
TP5: 0.000 VDC

Thank you so much for your knowledge and help walking me though this.
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I'm open to suggestion on what to buy, as long as it's not crazy expensive. I won't use a DMM much at all other than messing with this machine, so I don't need some pro-level device.

Readings now that the transformer is humming and getting power consistently:

TP1: 8.17 VDC
TP2: 1.67 VDC
TP3: 22.67 VDC
TP4: 3.1-3.21 VAC
TP5: 0.000 VDC

No, I didn't have J5 plugged in because I was following the troubleshooting directions of another site (https://homepinballrepair.com/troubleshooting-early-bally-and-stern-pinball-machines/#voltages). It seemed odd to me to have only J6 plugged in but I figured 1) he knows better, and/or 2) he would get to J5 in time. Wrong on both counts! More like trouble-causing than troubleshooting...

My J5 red wires measure 191.0 VAC.
My J6 blue wires measure 14.97 VAC
My J5 yellow & yellow-black wires all measure 7.47 VAC. (I tried all appropriate combos.)
My J5 green and orange wires measure 53.04 VAC.

Maybe. I'm surprised it's made it this long and far, if so!

Here are my latest measures with both J5 & J6 plugged in:

TP1: 8.08 VDC
TP2: 203.2 VDC
TP3: 14.97 VDC
TP4: 7.48 VAC
TP5: 46.23 VDC

Based on the aforementioned website and what you say about TP1, it appears all my values are in range. All this, due to a shoddy socket terminal at the power connector--which I only checked on a whim.

Reconnected, yes. Game working, no. I get GI but the multi-ball solenoid locks on, so that's my next quest--and perhaps another post on here if I get stuck.

Voltages with everything connected:

TP1: 8.14
TP2: 259.0
TP3: 16.68
TP4: 7.04
TP5: 46.31

Thanks, @dothedoo, I'll pull and check out the solenoid expander board this weekend. I just now powered up a couple times and had the solenoid both lock and not. It didn't lock on after I pulled and re-seated the connector on the expander board.

Are you referring to the underside bulb by the Aux Driver? It does light.

I feel similarly. I suspect I have voltage on the high end because I'm on my own transformer and I'm only about 1.5 miles from the substation. I've measured throughout the house and consistently get ~126VAC. I may buy another DMM just to get a second opinion.

I didn't know the input voltage is as adaptable as it is. Here are the voltages after changing to 120VAC input:

TP1: 7.54
TP2: 247.7
TP3: 15.69
TP4: 6.72
TP5: 44.15

Given how little I use a DMM and given I already plan to complain about the higher-range voltage, I think I'll let their calibrated and better equipment be my second opinion. If I'm right, they can tweak it; if I'm wrong, knowledge gained.

This is my concern. If I'm routinely at 126, I have zero headroom. I'll probably take more measurements during the coming weekdays to see if more draw along the lines ahead of me perhaps brings my voltages down at all, even if just a smidgen.

Okay, cool. Thank you!

I'm thinking beyond just my pinball machine but it sounds though it's of no consequence. Plus, they're technically still within tolerance range.

(As a northern transplant, I'm not always the most trusting of the southern methods of doing things. I get leery and suspicious at times.)

Thank you for the suggestion. I'll reach out to them this week.

Ah yes, good old ComEd. I lived in Aurora for 12 years, so I know them well. Sadly.

I wish that were what's happening. When it happens, mine locks on and the machine goes no further.

I only had a few minutes this morning to mess with it but the header does have cracked solders. I'll reflow the joints the next opportunity I have.

Thank you for pointing me in that direction. I'll give your mod a whirl, too!

I've always gotten phantom bumpers and kickers. I thought it was just me and mine!

The solenoid is behaving after I reflowed the connector. Thank you for the input; I'm going to inspect the relay anyway, just because.

At the risk of this original topic getting too far afield... I still have other things to chase down to get to full power-up and to attract mode. It sounds, literally and figuratively, as though I need to replace the S&T caps (and pots?) next. I have a little sound at first but then nothing but some louder buzzing. (I've always had some amount of buzzing, even when I first got it in 2000...for $500 off eBay!)