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CENTAUR II won't boot

Blake7

Blake7

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Joined
Jul 31, 2017
Messages
91
Location
Nottingham
Hi everyone got myself a centaur 2 of another forum member today as a project. It's my first machine so haven't really got much knowledge but not afraid to get my hands dirty.

Right when the machine is turned on a few lights will come on but it won't boot any further. The lights on the mpu flash 3 times. Just wondered if anyone has any ideas what to try first? I'll be doing some research online and trying a few things but thought I'd tap on the you knowledgeable folk first.

Thanks in advance
 
The lights on the MPU should flash 7 times for a successful boot so search online for what 3 flashes means (i can't remember off the top of my head). Have a look at the MPU board for any signs of battery damage, pretty common on these old Bally boards :thumbs:
 
Just realised your in Notts :thumbs: If you need a hand then I'm happy to come round to take a look with you.
 
The first flash with a pause does not count if I remember right? or I could be talking bollox
 
That's so kind ronsplooter thanks, there is a lot of batter damage on it, looks like a few of the PCB rails have totally corroded so I'll try replacing them tomorrow.
 
The following diagnostics are valid for Bally -17 and -35 MPU's, as well as Stern MPU-100/200 boards.
Upon power up, the on board LED should flicker briefly. Following this, the LED will flash, indicating completion of varying stages of the internal diagnostic program in the game ROM's. If the LED does not flash at all, check for proper checksums of the game ROM's, the ROM sockets, and the power supply voltages.

First Flash:
Signals the end of the ROM test.

Second Flash:
Test the NMOS RAM (U7). There will be a bit of a delay between the first and second flash, be patient. If no flash, replace U7.

Third Flash:
Tests the CMOS RAM (U8). If no flash, replace U8 - use caution the 5101 chip is NOT diode protected and is very static sensitive!

Fourth Flash:
Tests the first PIA chip (U10). If no flash, swap U11 for U10. Note that although you may get the fourth flash, U10 may still be defective.

Fifth Flash:
Tests the second PIA chip (U11). As above. If you have already swapped U10 and U11 and don't have the fifth flash, try a new 6821 in U11. If still no success, swap once more. Worst case-replace both PIA's.

Sixth Flash:
Tests the Display Interrupt Generator. This actually tests both U11 and U12. If U11 has been replaced, and no sixth flash, replace U12.

Seventh Flash:
Tests the "Zero Crossing Detector". This tests U10 and U14 as well as the presense of +43 volts from the rectifier board. If no seventh flash, check for +43 volts before changing anything else. Fuse F4 (+43 volt) is a common failure. Unless U10 has already been swapped for a new or known good 6821, change it before U14.
 
I'm just getting 2 flashes then in that case. The board does look in a pretty bad way lots of grey/dry looking joints and a few of the circuits corroded. How much are replacement boards if I'm not able to repair?
 
There are knowledgeable board guys on here - post some good photos including the front and back around the battery area.
 
Altek makes brilliant replacement boards.

With battery damage you might be best to send it to Andy Netherwood of Pinball Mania. Follow his guidance. You could muck about for ages and do more harm than good. He is very knowledgeable and trustworthy. And fair with pricing.

You got this at a low price so at least you can afford to buy stuff like this without being out of pocket.

Where abouts are you in Notts? I also live in this unfashionable county.
 
If it was my machine I would check that there is 5v going to the mpu board from the sol driver board first ,then chuck the mpu in the bin and buy a alteck mpu
Cheek all fuses and any lose wires
Good luck if I could do it anyone can !
 
the sockets can also go bad on original mpu boards,try cleaning the chip legs and reseating the 6821's and ram etc
 
Firstly congratulations on a total steal of a purchase.

I have limited experience but I have just done a total rebuilt of a toasted Bally -35 board and the good news is that yours does not sound as bad as it looks.

The fact you are getting 2 maybe 3 flashes out of it is good news as it shows that there is life in the old girl yet.

Better news is that your game is complete and, know it used to work and there are plenty of peeps on here that can help you get it back to 100%.

First thing I would do is remove the battery from the board, at this stage battery backup is not needed, and resist the temptation to power it up until you know how involved you want to get in fixing it.

Options I see are... Listed in cost Vs time.

Get a replacement new board.
Get your board fixed.
Exchange for a working one.
Fix it yourself.

My boards story is here in Posts #9 and #13

https://pinside.com/pinball/forum/topic/mmpc-first-ss-second-pin-coffee-table
 
Thanks for your input everyone, I'll post some pics tomorrow. Ill attempt to repair it myself first working on it is half the fun anyway isn't it.

DRD I'm from long eaton
 
Don't resist the temptation to press the self test on the sqwark n talk which if working is independent from the CPU. If reverb missing or trashed mypinballs does a fantastic repro pcb

 
For the price you got the machine buy a replacement altek board and repin the connectors then you should have a pretty decent game.
 
DRD said:
Altek makes brilliant replacement boards.

With battery damage you might be best to send it to Andy Netherwood of Pinball Mania. Follow his guidance. You could muck about for ages and do more harm than good. He is very knowledgeable and trustworthy. And fair with pricing.

You got this at a low price so at least you can afford to buy stuff like this without being out of pocket.

Where abouts are you in Notts? I also live in this unfashionable county.
Click to expand...

Thanks for the positive comments. However I don't repair battery damaged Bally mpus anymore. Uneconomic. Use an Alltek or a Fixit
 
First thing you should have done was remove all the connectors that supply power from the power board and test the voltages.
 
Steve brum just tried the self test on the sqwark n talk and got nothing
 
Last edited:
Logically, your first steps with an old girl like this are ....

1 download the manual
2 check all the fuses are correct as folk could have put anything in there. Including the one on the underside of the playfield
3 check the voltages on the touching points, compare to the manual
4 put balls in. Some of these old ballys will not go into attract mode unless there are enough balls in the trough
5 get @ronsplooter. Bribe him with premium continental lager. the quickest way to isolate problems on these games is to swap boards with known working games.

Or just take it to andy netherwood
 
Moonbus said:
Have a look at Nedreuds pacman thread here.

http://www.pinballinfo.com/communit...pac-maze-another-obsessive-restoration.34712/

It's the best visual display of checking power in these types of machines I can think of.

Download the manual and schematic from here... Just above the pics.

http://www.ipdb.org/machine.cgi?id=477

Good luck.
Click to expand...
Thanks for that I've checked the power supply and all voltages are spot on so that's a start. Here's some pictures of the mpu with some obvious battery damage. Doesn't look to difficult to sort so I'll give a a go later and get back to you all with the results. Actually can't upload the pics it says the fils wasn't a picture as expected? Tried .PNG and .jpg
 
If the power on the rectifier (power) and voltages are good the next thing to check is the big capacitor on the solenoid driver board, that's the one in the back-box with the big metal heatsink.

CAUTION ADVISED AS THE HIGH VOLTAGE IS EXPOSED ON THIS BOARD.

Label and disconnect the cables from the MPU board.

With the power supply board connected to the solenoid driver board check the voltages at the test points. The main one we are interested in is the 5v TP1 and 12v TP5.

If either of these are off then the MPU will run into issues.

Refer to here for more in depth info and solutions to all of your board issues.

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