Centaur/Alltek overvoltage issue

[mrsodapop]

I got a Centaur that has an Alltek MPU in it, that after it boots, lock
up, and the over voltage LED comes on.
When I power it up, the green +5 LED comes on, and the diagnostic LE
flashes 8 times. MOST of the time within 5 seconds of booting up the re
over voltage light comes on. A few times it will take 2-3 minute
before OV(overvoltage).
Here is what I have done: Replaced the 2 large caps(C23/C24) on th
sol. driver/voltage pcb, along with the LM323k voltage reg. transistor
Installed new pins at the MPU power wire connector. Replaced the diode
on the rectifier pcb for the 12vdc line(+5vdc unreg.)at the bottom o
the cabinet. I also swapped in another driver/voltage pcb from a know
working game with no change. Also verified a good ground at all pcbs.
My voltages are(with all connectors connected):
going into reg. from transformer for 12v line are 14.2vac
At TP3(after diodes) 15.92vdc
At TP5 on PS/driver pcb-15.89vdc
At TP1/3 5.12vdc
At Alltek pcb TP6(?) 5.1vdc
I have watched the 5vdc line during boot up on the Alltek-measuring i
on the pcb, and it is a rock solid 5.1vdc
I am guessing the overvoltage is from the 12v line being almost 16v
but am unsure how to bring it down, or if that is even part of th
problem.
Thanks for any help
Aaro

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mrsodapo

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[Drewscruis]

1) is this a new to you machine or have you owned for a while

2) was it working prior to you changing out the mpu and rebuilding the SDB.

3) have you checked to make sure the transformer hasn't been high tapped

4) have you measured your outlet voltage where you plug the pin into.

5) have you verified that another pin operates normally on the outlet your using for this one.

just a few ideas

I got a Centaur that has an Alltek MPU in it, that after it boots, locks
up, and the over voltage LED comes on.
When I power it up, the green +5 LED comes on, and the diagnostic LED
flashes 8 times. MOST of the time within 5 seconds of booting up the red
over voltage light comes on. A few times it will take 2-3 minutes
before OV(overvoltage).
Here is what I have done: Replaced the 2 large caps(C23/C24) on the
sol. driver/voltage pcb, along with the LM323k voltage reg. transistor.
Installed new pins at the MPU power wire connector. Replaced the diodes
on the rectifier pcb for the 12vdc line(+5vdc unreg.)at the bottom of
the cabinet. I also swapped in another driver/voltage pcb from a known
working game with no change. Also verified a good ground at all pcbs.
going into reg. from transformer for 12v line are 14.2vac
At TP3(after diodes) 15.92vdc
At TP5 on PS/driver pcb-15.89vdc
At TP1/3 5.12vdc
At Alltek pcb TP6(?) 5.1vdc
I have watched the 5vdc line during boot up on the Alltek-measuring it
on the pcb, and it is a rock solid 5.1vdc
I am guessing the overvoltage is from the 12v line being almost 16v,
but am unsure how to bring it down, or if that is even part of the
problem.
Thanks for any help
Aaron
--
mrsodapop
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[mrsodapop]

I would like to thank Dave at Alltek for helping to locate and fix the
issue I was having. It does look like the almost 16vdc on the 12vdc line
was causing the overvoltage IC to activate. Game is now running fine.
Aaron

[John Robertson]

Post by mrsodapop
I would like to thank Dave at Alltek for helping to locate and fix the
issue I was having. It does look like the almost 16vdc on the 12vdc line
was causing the overvoltage IC to activate. Game is now running fine.
Aaron

Appreciate your posting that you fixed the problem with Alltek's help!

And how did you fix this?

It is nice to quote from previous messages so people have a clue what
the story is about...

John :-#)#

[barakandl]

Post by John Robertson

Post by mrsodapop
I would like to thank Dave at Alltek for helping to locate and fix the
issue I was having. It does look like the almost 16vdc on the 12vdc line
was causing the overvoltage IC to activate. Game is now running fine.
Aaron

Appreciate your posting that you fixed the problem with Alltek's help!
And how did you fix this?
It is nice to quote from previous messages so people have a clue what
the story is about...
John :-#)#
--
(Please post followups or tech inquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
[phone] or Fax [phone] (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

Just ignore it? Seeing 16v on the unregulated bally 12v circuit is fairly common. I never mess with it as long as it is over 12v and the +5v looks good.

[John Robertson]

Post by barakandl

Post by John Robertson

Post by mrsodapop
I would like to thank Dave at Alltek for helping to locate and fix the
issue I was having. It does look like the almost 16vdc on the 12vdc line
was causing the overvoltage IC to activate. Game is now running fine.
Aaron

Appreciate your posting that you fixed the problem with Alltek's help!
And how did you fix this?
It is nice to quote from previous messages so people have a clue what
the story is about...
John :-#)#

Just ignore it? Seeing 16v on the unregulated bally 12v circuit is fairly common. I never mess with it as long as it is over 12v and the +5v looks good.

If the Alltek MPU is seeing it (16V+) as a problem I would like to know
what was done to 'fix' it.

I could simply ask Dave, but thought the originator of the post would
like to elaborate. That way others could find the answer if they were
searching, and save bugging Dave!

John :-#)#

[mrsodapop]

HI All,
Sorry for the delay getting back to this, been away for a while.
Here is details. From what I understand some Ballys just run a littl
high on the 12vdc circuit, this one runs at about 15.89. The Alltek MP
is sensitive enough to detect this and consider it "over voltage". Th
solution was to remove the lower left IC (U17?). I do not have th
schematics in front of me now, but I believe this is the over voltag
regulator. After removing this (U17), the system bypasses the ove
voltage circuit.
Perhaps someone could explain why some - or this machine run high o
the 12vdc circuit. My AC voltage going into the diodes is 14.2 -14.3vac
spec. is 14.2vac. Voltage coming out of (old/original) diodes wa
15.96vdc(TP3 on rectifier pcb), I replaced the 4 diodes and TP3 is no
15.89vdc. So why is voltage high if I have factory spec. ac voltag
going in, with proper original and replacement diodes BOTH producing
high DC voltage?
Thanks for interest
Aaro

--
mrsodapo

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[mrsodapop]

Oopps, forgot to address some good ?? from drewscruis. This game belong
to a
friend of mine(never seen it before). According to him it was workin
fine for some time, and sat for several months, after powering up th
problem surfaced.
The outlet is one that I use for testing games in for repair. It is
rock steady 122 vac with only 1 duplex outlet on the 15A circuit.
Aaro

--
mrsodapo

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[[e-mail]]

Post by mrsodapop
HI All,
Sorry for the delay getting back to this, been away for a while.
Here is details. From what I understand some Ballys just run a little
high on the 12vdc circuit, this one runs at about 15.89. The Alltek MPU
is sensitive enough to detect this and consider it "over voltage". The
solution was to remove the lower left IC (U17?). I do not have the
schematics in front of me now, but I believe this is the over voltage
regulator. After removing this (U17), the system bypasses the over
voltage circuit.
Perhaps someone could explain why some - or this machine run high on
the 12vdc circuit. My AC voltage going into the diodes is 14.2 -14.3vac,
spec. is 14.2vac. Voltage coming out of (old/original) diodes was
15.96vdc(TP3 on rectifier pcb), I replaced the 4 diodes and TP3 is now
15.89vdc. So why is voltage high if I have factory spec. ac voltage
going in, with proper original and replacement diodes BOTH producing a
high DC voltage?
Thanks for interest
Aaron
--
mrsodapop
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Its actually U13 and I had the same problem in a working pin after installing a new Rectifier board. The over 5 volt LED light came on and the Allteck MPU would not boot. Removed U13 and its boots perfectly

[John Robertson]

Post by ***@gmail.com

Post by mrsodapop
HI All,
Sorry for the delay getting back to this, been away for a while.
Here is details. From what I understand some Ballys just run a little
high on the 12vdc circuit, this one runs at about 15.89. The Alltek MPU
is sensitive enough to detect this and consider it "over voltage". The
solution was to remove the lower left IC (U17?). I do not have the
schematics in front of me now, but I believe this is the over voltage
regulator. After removing this (U17), the system bypasses the over
voltage circuit.
Perhaps someone could explain why some - or this machine run high on
the 12vdc circuit. My AC voltage going into the diodes is 14.2 -14.3vac,
spec. is 14.2vac. Voltage coming out of (old/original) diodes was
15.96vdc(TP3 on rectifier pcb), I replaced the 4 diodes and TP3 is now
15.89vdc. So why is voltage high if I have factory spec. ac voltage
going in, with proper original and replacement diodes BOTH producing a
high DC voltage?
Thanks for interest
Aaron
--
mrsodapop
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This USENET post sent from http://rgparchive.com

Its actually U13 and I had the same problem in a working pin after installing a new Rectifier board. The over 5 volt LED light came on and the Allteck MPU would not boot. Removed U13 and its boots perfectly

From Dave, the designer of the Alltek MPU:

"The over voltage chip looks at the +5vdc line, not the 12vdc line.
What people don't understand is the over voltage a lot of the times is
the AC on the DC line because the large blue cap on the SDB is bad. So
you get 5vdc plus as much as 10.5vac riding on the DC signal too. That
is why the chip shuts down the board for protection. With this said it
doesn't mean a chip doesn't go bad. It's rare but it can happen too."

So do NOT remove the overvoltage protection circuit unless you want bad
things to happen to your board. This will obviously void the warranty too!

John :-#(#