Centaur is a little rough looking motorcycle themed game, colored in mainly black and white.
The playfield needs some fixing. As the saying goes, it is a little worn from where the ball goes!
But this is a rare and great game, so I just had to buy it despite the wearing. And the price was
not very bad.
Someone has obviously tried to fix up the playfield with a Sharpie. Not much success.
Connected to the sound board is a "Say It Again" module, an analog reverb unit that adds
a dramatic echo to the games speech. Good thing that the board is in place. They are very
difficult to find today.
Backglass is fine. But the sound board has a little problem. There is speech but no sounds.
Needs some checking. More serious problem is on the display power supply. There was some sparking
on one display, and I checked the display voltage, that should be 170-190 volts. It was 250 V!
Power off quickly, and not back on until it is fixed! The displays burn out very quickly with this
kind of overvoltage.
Reason for the overvoltage was found, the 2N3584 transistor in power supply board was
shorted. High voltage transistors in TO-66 case are hard to find, at least from my spare
supplies, so I decided to replace it with a TO-220 cased BUT11A. It requires some extra
wires but works as well. Or, would have worked, but still after replacing the transistor
there was no display voltage. A 22 kohm resistor R51 has burnt open. Of course no replacement
available on my toolcase. Must replace that the next time I go to our gameroom. The other
transistors seem OK, so after replacing R51 displays should be fine again.
Replacing R51 was not enough! The two other transistors were, after all burned. Luckily
I had enough spares with me, and now the power supply works fine. Time to begin inspecting the
sound board problems.
The sound board is now OK. Problem was in dried out capacitor C43, and also the volume
controlling opamp U14 (LM3900) had to be replaced. But now all sounds come out loud and clear.
Except, the Say It Again module is not echoing the speech as it should. Probably the fault
is in SAD4096 echo IC, I will check that when I get an oscilloscope with me. A multimeter is
not enough for these problems.
The playfield lights were somewhat unstable, and I had to replace the J3 connector between
cabinet and backbox, thru which all power goes. It worked fine for a while, then the load was
too much for the old rectifier and that needed replacing too. The old bridge rectifier was
missing its mounting screw, so it was not attached to heat sink at all. No wonder it failed.
The game plays really good, so it just needs the echo board fixed, and Kauko already promised
to use his magic touch on the playfield paint. This will be a really great piece of my collection.
Centaur has been played for a year, but only recently I found out it is missing some
of its speech. Not completely silent, but not talking very much either. And the problem?
Really simple. There are 5 ROM sockets on the sound board, but only three ROMs. And of
course one of them was in the wrong place. The ROMs should be in sockets U3, U4 and U5,
but for some reason the U3 chip was in U2 socket. The board worked but half of the speech
was missing. Now the game is very talkative! Echo board problem was indeed found to be in the
echo chip SAD4096, very hard chip to find today. But the game sounds nice even without echo.
I removed the suspicious looking memory backup battery from CPU board, and installed a gold cap in its place.
No more worrying about leaking battery destroying the PC board.