In your country, Pinball was 5 balls per game in the era when Centaur came out.

I've had similar issues (different programmer) with ST 2716 and 2732 EPROMs from China and found that repeat programming the chips multiple times (5 or so) without erasing between programming and switching blank check off gets them to work.
Problem is the Chinese are remarking these chips - they may have been a different brand of EPROM requiring different programming algorithm, not the ST one.
Plenty of the Chinese sourced 2716 & 2732 EPROMs I've bought have worked fine though.

Bally playfields have a little divot near the tip of each flipper. You align the centre (pointiest) part of the flipper tip to the divot.

See the example on a Medusa below:
You have your flippers set up past the divots such that flipping to the left drop targets is weaker.

IMG_0013a (resized).jpg

Hi @Jappie, the wire color codes are in the schematics on the "Wiring Diagram Backbox" page.

I hope the below helps explains how the wire color codes are listed: specifically the gray wire goes to pin 15.

Centaur_MPU_Wiring.jpg

It looks like a stepdown transformer and a rather small one for this application.

Does the game have the original Bally transformer on the large metal power module? If yes you can bypass that stepdown transformer - just make sure the original Bally transformer is wired for 115V - see the below picture of the voltage selector jumper block located next to the main transformer.

NOTE, you will need to change the red varistor shown in your second picture with one of these:
https://www.greatplainselectronics.com/proddetail.asp?prod=V130LA20AP

And change the inline EMI filter for one capable of higher current:
https://www.greatplainselectronics.com/proddetail.asp?prod=ZHG2206-H

PS-54_Config.jpg

Sorry, without knowing where the wires on that red switch are hooked up to it's impossible to know. If you can trace where they go then I can comment.

Whoever wired the transformer in this game didn't know what they were doing. You'll have to make up two jumper wires with crimps since the game only has one at the moment and you need three.

BTW, it's the block connector sitting on the bracket with the mains fuse next to the transformer.

Transformer_Centaur1.jpg

See here:
https://pinside.com/pinball/forum/topic/centaur-clubmembers-only/page/24#post-5895568
https://pinside.com/pinball/forum/topic/centaur-clubmembers-only/page/24#post-5897382

At the magnet, the yellow wire should have 43V. The black-red wire connects to the solenoid driver board at J5 pin 3 which switches ground to the magnet.
So if you manually ground the black-red wire at the magnet, this applies in-game power to it. Does it work?

The 51 ohms you measure across the coil is a good sign - that's the reading I got on one I measured about two years ago. So I wouldn't be suspecting it just yet. Problem is I'm not aware of anyone selling them off the shelf - I looked a while back because my Centaur is missing the factory magnet . Someone fitted a later WMS magnet in mine which is too strong and regularly blew a 3amp slow blow fuse I put on it.

If I remember right:
The magnet has a PTC thermistor in it or something similar - no idea what its value might be.
The gauge on an original Centaur magnet wire I measured was roughly somewhere around 30 or 31AWG - don't quote me on this. There are online calculators to estimate the number of turns. I have to find it again.

If grounding the black-red wire on the magnet works, then go upstream:
* Ground the metal tab of the Q18 driver transistor on the solenoid driver board to manually activate the magnet.
* Further upstream, ground pin 11 of U4 on the solenoid driver board to manually activate the magnet.

If you have no luck when you visit it, post some clear pictures of the magnet showing the screw puncture.

Cheers, they sound pretty confident it's 27 gauge wire. 51 ohms calculates to about 1000 feet of wire.
https://www.cirris.com/learning-center/calculators/133-wire-resistance-calculator-table

Great!
Do you by chance have a micro gauge to measure/confirm the original coil wire gauge?

You're too kind however I don't live near the US so it wouldn't be feasible. Appreciate the offer though.

CPRs done a small batch of oldskool silkscreened Centaur playfields:
https://classicplayfields.com/shop/pinball-playfields/centaur-2/

There is no feature to disable the magnet.
The magnet is controlled by the signal leaving the MPU board at J4 pin 8 (green-black wire) and goes to the solenoid driver board on J4 pin 10.
Have you re-terminated the J4 MPU connector yet?
This signal should go logic low when the magnet is to be activated.

MPU board J1 pin 1 is the 'ones' digit enable signal that goes to pin 4 on all the displays. Schematics say it's a black wire.

The game wants to see all the balls on power-up before going into proper attract mode, otherwise the displays will all flicker "0000000". So make sure there's 5 balls in the outhole area.

The game requires the solenoid voltage to be working in order to boot which your game is doing. The power-supply board is unlikely to be the issue.

Give vec-tor some feedback to his diagnosis points in post #1513 to help narrow down the problem. If you're not sure on an item let us know and we will go into further detail.

Switch #16 (Slam) is different to the Tilt switches at #15
If a player slam tilts the machine the consequence is the game resets as a punishment for excessively rough behavior.
If a player just tilts the machine they lose their ball in play.

There are two slam switches and they're weighted.
One is on the back of the coin door to sense when someone kicks the door.
The other is near the tilt plumbob that senses when someone lifts the game then drops it.

The outhole is where the ball goes when you lose the ball in play.

Centaur_Outhole.png

Awesome explanation, thanks @vec-tor!

It's in the manual on IPDB - page 24 of 44. Numbers in circles are switch test mode numbers, numbers in square boxes are solenoid test mode numbers.

The diode isolates that switch to a single point in the matrix. Without it, the switch closing will falsely cause other switches in the matrix to appear as closed at the same time.

You haven't mentioned if the game is not detecting the switch 08 closure or if it's always detecting switch 08 is stuck closed (stuck switches are put on the ignore list to prevent the game repeatedly scoring because of it).
So what is switch test mode telling you about the outhole? Stuck or never detecting it closing?

BTW when you start a game, the ball should be kicked to the shooter lane regardless of the state of the outhole switch. It's only when you lose the first ball that it won't respond.

No, because the diode is in series with the switch, not parallel across the switch.

How is your multi-meter test of that diode going? make sure you do it with the machine OFF.

You want the standard "AQ-25-500/34-4500" coils as supplied on Centaur and Ballys of that era.
The other AQ coils are weaker in different senses. The last option "AF-25-500/28-1000" coils are for electro-mechanical games and is not suitable for Centaur.

The idea is that the metal mass of the plunger on the older flipper mechs is less than the longer plunger on the linear mech so the old mech is able to generate a bit faster thrust.
I can't quantify what difference it will make in your game.

The crusty linear mechs in my Centaur play decent enough, the Queens chamber shot to the end is hard but do-able.

Regarding returns from the outlanes, as sleepygtr said it's all in the nudge. I get a good percentage back in play which can make for long ball times.

vec-tor beat me to it but here's another pic from post #963 earlier in this thread: both input and output signals are shielded.

Centaur_S&T_to_SayItAgain.jpg

You can always make your own with thinner shielded cables and no glue.

See the schematics. The audio signals use shielded wire.

S&T audio signal out J2 pin 9 to the Reverb board at J2 pin 6
S&T shield around the audio signal out J2 pin 10 to the Reverb board at J2 pin 5

S&T audio signal in J2 pin 7 to the Reverb board at J2 pin 2
S&T shield around the audio signal in J2 pin 8 to the Reverb board at J2 pin 1

S&T_AudioWiring.png
SayItAgain_AudioWiring.png
Wiring_Reverb.png

Go into audit mode via the little red self test button inside the coin door. Keep tapping it until the Ball In Play display shows setting number '18'. Then hold the start button to change the setting (shown on the player displays) to "03".

SoundSetting.png

You're right. On Centaur, if set to "2 coins / 1 credit" for example, the first coin drop produces a laugh, the second coin drop it says energize me and adds the credit.

I can map out all the speech on the sound boards for both games if you want - a late night project.

Fathom speech will be posted in the Fathom club thread

The following is the list of the sound commands (in HEX) sent to the S&T board that produce speech on Centaur: Comms between the MPU board and S&T are 4 bits wide so commands are sent as two nibbles - lower nibble first then upper nibble.

The sound board test button plays these speech phrases in backwards order:

30= 2X completed
31= 3X completed
32= 4X completed
33= 5X completed
34= Completed
35= Power Orbs
36= Begin Orbion Attack
37= Energize Me
38= Energize Power Orb
39= Activate Power Orb
3A= Power Orb
3B= Guardian Releases Power Orb
3C= Release Power Orbs
3D= Energize
3E= Bad Move Human
3F= Slow Aren't You

40= Sequence Activates
41= Release Target Activated
42= Sequence
43= Only Single Value
44= Side Awards Double
45= Try
46= Doubles Queens Chamber
47= No Class Human
48= Challenge Me
49= Orb Feature
4A= Sequence Feature
4B= Chamber Feature
4C= Guardian Feature
4D= Bonus Feature
4E= Destroy Centaur
4F= Human

50= Centaur
51= Powerlane
52= Ha Ha Haa (laugh)
53= Activated
54= Maximum Orbion Strength Achieved

Yours is correct, but I think you knew that
Factory alignment is the flipper tips to the divots. Same for all Ballys of that era. Here's Medusa as a reference with the lighted inserts under the flippers.

Must be awfully tough hitting the inline drop targets from the left double chamber lane on that location game.

IMG_0013a.jpg

Only one of the ground wires is connected at the Say It Again board, it's to prevent ground loops.

Without hearing your issue, first guess would be a corrupt speech ROM.

A NO26-2300 coil is actually less powerful than a NO26-1900.

You can probably disable the attract mode G.I. flashing (so the G.I. is always on) in game over mode by using the Game Over lamp control wire with a diode to keep the flasher on. When the Game Over lamp is off it will have no effect on the G.I. flashing in game mode.

Try either of these solutions:

1) Jumper a wire from the bottom leg of resistor R14 on the lamp driver board to the non-banded side of a diode. Jumper another wire from the banded side of the diode to the top leg of resistor R33 on the lamp driver board. These resistors/locations are dependent on having a factory Bally lamp driver board. Probably better to use a low dropout diode like a 1N5819 but a 1N400x might do.

or

2) Jumper a wire from the game over lamp (Grey-White wire) to the banded side of a diode. Jumper another wire from the non-banded side of the diode to the White-Black wire at the flasher trigger lamp.

Which ever way you go try to make it easily reversible for the next owner.