I bought the machine about 3 months ago and it worked fine. I turned it on yesterday and it does not work. The lights are on behind the back glass and only 3 lights are illuminated on the playfield. The first light on the left blinks and the other two are solid red.

I am new to owning pinball machines and am still learning the ropes so any help would be greatly appreciated.

My Centaur has the old fashioned power cord (no ground prong) but I would disconnect it from the power outlet when not in use. I hope to either replace the cord with a standard grounded 3 prong type or plug the existing cord into a powerstrip.

Should I look at the MPU and see if it blinks? Could it be a blown fuse?

Thank you.

Centaur (resized).jpg

Thanks. I will try out your suggestions next week and see if any of it fixes the problem.

I just checked the MPU. I get a solid green light on the MPU LED. There are five fuses next to the transformer. None of them look black (not sure if the fuse glass turns black when the fuse burns out) - I guess the only way to check if they need to be replaced is to use a voltmeter.

I have noticed that when I open the headboard door the lights from the top of the playfield (see the previously posted photo) turn off and the lights inside the queen's chamber light up. I guess at this point checking the fuses is probably the best route.

I have two LEDs. The upper right board (MPU) LED is solid green when I turn on the machine while the bottom right board (lamp driver) LED displays 5 flashes.

I decided to post a short video about my Centaur problem. My understanding is that during the boot up the MPU board is supposed to flash 7 times while the sound board is supposed to flash 5 times. I incorrectly refer to the two in the video.

I may need to go shopping again at Marco Specialties:

https://www.marcospecialties.com/control/keywordsearch?SEARCH_STRING=centaur

I unplugged all 4 cables on the MPU and plugged them back in. I got the same result - I have not tested the voltages on the MPU but chances are that if there are problems on the MPU I might as well replace the whole board as I would not know how to fix it. The MPU light continues to be solid green.

I ended up ordering a new MPU, Solenoid, and Test board from here: https://allteksystems.com/products-mpu-replacements.html

I gave up after reading the following and decided to just replace the boards:

No Flashes: the LED is Permanently On:

If you turn your Bally game on, and the LED stays on continually, this is one of the hardest problems to fix on these boards. A stuck on LED can be caused by any (or all!) of the following:

The reset circuit is damaged (after all, it's in the battery corrosion area!). This includes transistors Q1 and Q2 (both 2N3904), Q5 (2N4403), and diodes CR5 (1N4148 or 1N914) and VR1 (1N959B or 1N4738A).
The program ROM (read only memory) at U6 is bad.
The ROM jumpers are incorrectly set for the U6/U2 ROMs installed.
The U9 CPU microprocessor is bad.
The U11 PIA (peripheral interface adapter) is bad.
ANY of the sockets for chips U6, U9, U11 are bad.

The first and last points are probably the most common problems.

Copied from: http://techniek.flipperwinkel.nl/ballyss/rep/index2.htm#fixture

I will try reconnecting all 4 MPU connectors while powered on and see what it does. I also came across another great resource on fixing Bally pinballs (1977 to 1985):

http://techniek.flipperwinkel.nl/ballyss/rep/index1.htm

Reconnecting the MPU female connectors had no effect other than showing a new playfield light pattern (around dozen of the playfield lights were illuminated) when the bottom left female connector was not plugged in and the other 3 female connectors where plugged in. My next step is to replace the MPU board.

BigAl56

You are right -I did make a mistake in the early part of my video confusing the MPU and S&T boards but I did correct myself later on in the video. Like I said, I am new to repairing pinball machines. Thanks for your feedback.

I am happy to report that I have repaired my Centaur pinball machine. As Startek2 mentioned the key to repairing it was replacing the MPU board. I also went ahead and replaced the solenoid board. I chose Alltek boards as they are fantastic in both design, quality, ease of use and price. Alltek's MPU board covers any solid state pinball machine. Also, they enable free games.

https://allteksystems.com/ordering-bally-stern.html

I have attached the newly installed board images.

Once you replace the MPU board make sure to set the DIP switches as indicated on my photos. The last step is configuring the audio settings:

1. Turn the game on.
2. Open the coin door.
3. Push the small button inside (Self-Test button).
4. This will start testing and setup. Look at the backglass and push the button until you get to 18.
5. Then push the Start button (front of the coin door) until the other number goes to 3. That will turn on all sound.

I have also attached the backglass setup photo.
Alltek Centaur Game Settings DIP (resized).jpgAlltek Centaur DIP (resized).jpgAlltek solenoid board (resized).jpgnew Alltek boards (resized).jpgsounds (resized).jpg