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CENTAUR II won't boot

The fact that your getting two flashes squarely points at the power supply being adequate and the reset section is functioning. You've got corrosion which clearly points to board damage. 2 flashes means U8 is damaged which is right at the bottom in the corrosion zone. Start there and see what happens.
 
As above. Power seems in order, so you have a good foundation to start assessing the MPU.

Something fun to do whilst waiting for MPU bits is to look at the sound board. Feels great when they burst into life.

When you power on are you getting any flashes on the sound board led?
 
I've just cleaned up the board and repaired any breaks in the circuit now the mpu flashes constantly
 
Time to look at U7 and U8 on the MPU.
I guess either the sockets or IC's are bad or both as in my case.

Before going all out on re-socketing...

Try carefully removing the IC's and re-solder the socket bases from the backside.
Replace the IC's and see if you get any further on the flash sequence.

In the long run it is advised to replace the old sockets. At the moment I guess you just want to see the game boot up.

Regarding sound.
Are you getting a slight hum from the speaker?

If you are there are two potentiometers next to the heatsink on the sound board. These are volume controls, one for voice and the other for background sounds. Try rotating them both to max and min a few times to clean the internal contact surfaces.

If no hum then check the cables from the speaker to sound board and the volume control potentiometer mounted on the door.
 
I've done a couple of classic Bally Solid State MPU boards and HIGHLY recommend a bench power supply. You can make one from an old computer PSU.

It is SO much easier to be able to work on then test the board out of the game. A logic probe is a must too.

I found it fun and very rewarding bringing them back to life.

Consider re-capping the Squawk And Talk board too. Really cleans up the sound.
 
stoptap said:
I've done a couple of classic Bally Solid State MPU boards and HIGHLY recommend a bench power supply. You can make one from an old computer PSU.

It is SO much easier to be able to work on then test the board out of the game. A logic probe is a must too.

I found it fun and very rewarding bringing them back to life.

Consider re-capping the Squawk And Talk board too. Really cleans up the sound.
Click to expand...
Second this, especially if you are going for a rebuild.
 
No sound at all no buzz or hiss. I checked continuity of u7 earlier and all was good so shouldn't be the socket I've not check u8. Thanks again for your help
 
If there's corrosion around the socket of U8 then there will be corrosion inside the socket and more often that not the spring contacts will be broken internally. With some sockets you ease off the plastic leaving the contacts intact if they are good or they'll snap off if they are corroded. Then either replace the plastic surround or put in a new socket.
 
Blake7 said:
No sound at all no buzz or hiss. I checked continuity of u7 earlier and all was good so shouldn't be the socket I've not check u8. Thanks again for your help
Click to expand...

No probs, I'm on holiday and got nothing else to do.

Do you have a flash sequence on the sound board when you power up?

If you do, manipulate the 3 potentiometers, 2 on the sound board and the one in the door. And test the 2 wires going from the speaker to J2 on sound board. 1 wire will go via the pot on the front door.
 
Got sound now the resistor in the door has to be all the way up for it to work and it's very low volume and distorted
 
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Yeah 1 slow flash then 4 fast got sound now if the door volume is all the way up but low and bad quality
 
Moonbus I'm very happy to report we have sound. The problem is with the volume resistor on the board the plastic bit you turn has fallen off. If I force it to make contact we have sound and decent quality.
 
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Yay. You will need two 1k pcb mount pots. I got some from maplin. Will also need a panel mount one for door.

Glad it is working as those sound boards are gold dust.
 
Hi @Blake7. Congrats on the CENTAUR II steal ;)

As for fixing the MPU, get it out of the backbox and onto the test bench (or kitchen worktop or whatever). Get yourself an old PC power supply as they generate rock-solid 5V and 12V. This means you can get everything else out of the picture that might be causing a problem, e.g., a short in the wiring loom or crappy ground on the backplane. It's easier to test and repair, and no 180V supply to accidentally killed yourself with. Only thing to note is you won't get the 7th flash on the bench because there's no +43VDC from the solenoid circuit. You can spoof this however for testing.

As mentioned by @astyy the are lots of pics and notes on my shoplogs for PARAGON, GOLD BALL and PAC-MAN.

Post on PARAGON has details about setting up the PC power supply and how I fixed only having 2 flashes: http://www.pinballinfo.com/communit...storation-1978-bally-paragon.6519/#post-39559

Some very technical fault-finding the -35 MPU from my GOLD BALL starting on this post: http://www.pinballinfo.com/communit...tures-in-budget-restoration.14097/#post-80277

I'm sure you'll find all my shoplogs useful/interesting as I only collect and restore old Bally pins from the 70s and 80s, so between the 4 I've got (I have a VECTOR too!) I've got exactly the same parts as in your CENTAUR. Definitely rebuild the POWER and REGULATOR modules as they're quite badly designed. The original bridge rectifiers on the POWER MODULE are underrated (see http://www.pinballinfo.com/communit...in-budget-restoration.14097/page-2#post-81701 and http://www.pinballinfo.com/communit...storation-1978-bally-paragon.6519/#post-39549), and the big capacitors on the REGULATOR will be totally buggered after nearly 40 years (details on this PARAGON post: http://www.pinballinfo.com/communit...ion-1978-bally-paragon.6519/page-3#post-52806)

Good luck and help and advice here when you need it. Thank you for rescuing another classic Bally :clap::clap::clap:
 
@Blake7
Man I wish I had that list of links before I dived in blind to this pinball lark a year ago.

@Nedreud your documentation this side of the pond is a live saver / game changer for starters like me.
 
My pleasure, @Blake7!

Actually, the best online resource has already been linked earlier by @astyy: http://techniek.flipperwinkel.nl/ballyss/rep/index1.htm Absolute goldmine of information. As is the Bally/Stern section of PinWiki: http://www.pinwiki.com/wiki/index.php?title=Bally/Stern

Other useful links:

http://home.pacific.net.au/~jennyah/BUX84.htm
http://zerocharactersleft.blogspot.co.uk/2014/07/retro-pinball-reverse-engineering-bally.html
http://www.pinrepair.com/bally/squawk.htm
http://www.techdose.com/projects/6116-to-5101-RAM-Adapter-for-Stern-MPU100/361/page1.html
https://www.flippers.com/coil-resistance.html
http://stevekulpa.net/pinball/bally.htm
http://home.scarlet.be/~leonb1/eindex.html
http://homepinballrepair.com/
http://www.pinball4you.ch/okaegi/pro_soft.html (custom CENTAUR ROM)
http://www.planetarypinball.com/partmanuals/
http://arcadeuk.blogspot.co.uk/
http://www.pinball4you.ch/okaegi/pro_pck.html
http://www.bigclive.com/centaur.htm (DIY "Say It Again" echo for CENTAUR)
 
Thanks ever so much guys I can't believe how helpful everyone has been and I've learnt so much already.

I'm going to get a 5101 ram ordered today which I'm hoping will get the mpu working. I've cleaned it up and replaced the parts that are most commonly damaged from the battery damage. If the ram doesn't sort it when it arrives I'm thinking I'll splash out on an alltek.
 
The good thing about altek mpu boards is that you can switch them between games as they have all the software built in. You just change dip settings to select the relevant game's software. Swapping between fathom and paragon took ne 5 mins.

If you end up with a few old ballys, like many of us have, it is so much easier this way

If you use the original mpu boards to board swap, you have to change roms and jumper settings which is fraught with perils.
 
DRD said:
The good thing about altek mpu boards is that you can switch them between games as they have all the software built in.
Click to expand...
Can you run the various versions of machine software, the custom home ROMs & wot not?
 
There is a bank of 8 dip switches. You just select the game. I don't think you select different rom versions but I have never looked into it.
 
Just been having a fiddle and it looks like I need a replacement 'say it again board' I'm not getting any echo and the crackle is coming from this board. Seems a very common fault.
 
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