Tech: Bally Centaur 1amp playfield fuse blowing on startup

[cdnpinballer]

I am just about done a playfield swap on a bally centaur.

On immediate powerup the 1 amp fuse under the playfield close to the
flippers blows and all solenoids except the knocker do not work.

However, if I clip the wires to the outhole kicker, replace the fuse
and power up all solenoids fire except of course the outhole kicker
and ball lauch coils.

All coils move freely and no coils are locked on at start up.

What I have done so far: replaced solenoid driver board with a known
good working one, replaced coil with a used one I had that I thought
was working fine and I have looked for shorts on the +43 volt bus line
but have not found any.

Short of tearing my wiring harness appart to really dig deep for a
short somewhere what else should I be looking at?

Also, all connectors have been repinned on MPU & SDB.

Any ideas?

[cdnpinballer]

Sorry, I replaced the outhole coil with a used one I had.

Could it be the outhole coil diode or a diode on one of the coils of
the ball launch mech?

[stevekulpa]

This may be a redundant reply as I *thought* I replied via GG, but I
still don't see it, so I'll try again from RGPArchive...

Sounds to me like you have a shorted diode on the outhole coil, or the
coil is wired up backwards. In either case, the first time the outhole
coil fires, then releases, the driver transistor for that coil will fry.
If the transistor should short rather then blow open, that would mean
that coil is now permanently on. So every time you start the machine,
that coil will energize, and stay energized, until the fuse pops.

The coil should be wired so the fat wire(s) are connected to the same
lug that is connected to the banded end of the diode. The single skinny
wire goes to the other lug. Regardless, try replacing the diode, and
make sure you wire it up properly. If the wires on both lugs look the
same (both fat or both skinny), replace the term "fat wire(s)" with the
wire that visits all the playfield coils in a daisy-chain fashion.
Typically on Ballys, an 18AWG wire comes off the fuse holder, then hops
from coil to coil, visiting each lug supplying the +43VDC to the coils.
It's this +43VDC bus that must be connected to the same lug that is
connected to the banded end of the coil's diode.

You'll probably have to replace the transistor too. Q4 on the solenoid
driver/regulator board controlls the outhole for Centaur II. I assume
it's the same for Centaur, but I do not have a Centaur manual to confirm
that.

steve


--
stevekulpa

Steve Kulpa (cargpb10)
Nolensville, TN
http://stevekulpa.net/pinball/pinball.htm - Pinball
http://stevekulpa.net/pinrepair/pinrepair.htm - Repair
http://stevekulpa.net/faces/rgpidx.htm - Faces
This USENET post sent from http://rgparchive.com

[Steve Kulpa]

> the ball launch mech?- Hide quoted text -
>
> - Show quoted text -

I think the replacement coil has a shorted out diode, or you hooked it
up backwards. Then the first time that coil fired, it took the driver
transistor out, which is now shorted. So when you turn the machine
on, the shorted transistor turns the coil on permanently, which then
blows the playfield fuse.

Double check your coil wiring - the fat wire(s) must be connected to
the coil lug that is also connected to the banded end of the diode.
The single skinny wire goes to the other lug. If it's wired properly,
try replacing the diode. Then replace the driver transistor
regardless. I don't have a Centaur manual handy, but the Centaur II
manual says that would be Q4 on the solenoid/driver board. I would
think it would be the same on Centaur too.

steve
---

[cdnpinballer]

On Feb 22, 11:46 am, Steve Kulpa <stevekulpa...@gmail.com> wrote:
> On Feb 22, 10:36 am, cdnpinballer <cdnpinbal...@hotmail.com> wrote:
>
>
>
>
>
> > On Feb 22, 11:34 am, cdnpinballer <cdnpinbal...@hotmail.com> wrote:
>

> > > I am just about done aplayfieldswap on a bally centaur.
>
> > > On immediate powerup the1ampfuseunder theplayfieldclose to the

> > > flippers blows and all solenoids except the knocker do not work.
>
> > > However, if I clip the wires to the outhole kicker, replace thefuse
> > > and power up all solenoids fire except of course the outhole kicker
> > > and ball lauch coils.
>
> > > All coils move freely and no coils are locked on at start up.
>
> > > What I have done so far: replaced solenoid driver board with a known

> > > good working one, replacedcoilwith a used one I had that I thought

> > > was working fine and I have looked for shorts on the +43 volt bus line
> > > but have not found any.
>
> > > Short of tearing my wiring harness appart to really dig deep for a
> > > short somewhere what else should I be looking at?
>
> > > Also, all connectors have been repinned on MPU & SDB.
>
> > > Any ideas?
>

> > Sorry, I replaced the outholecoilwith a used one I had.
>
> > Could it be the outholecoildiodeor adiodeon one of the coils of

> > the ball launch mech?- Hide quoted text -
>
> > - Show quoted text -
>

> I think the replacementcoilhas a shorted outdiode, or you hooked it
> up backwards.  Then the first time thatcoilfired, it took the driver

> transistor out, which is now shorted.  So when you turn the machine
> on, the shorted transistor turns thecoilon permanently, which then
> blows theplayfieldfuse.
>

> Double check yourcoilwiring - the fat wire(s) must be connected to
> thecoillug that is also connected to the banded end of thediode.

> The single skinny wire goes to the other lug.  If it's wired properly,

> try replacing thediode.   Then replace the driver transistor

> regardless.  I don't have a Centaur manual handy, but the Centaur II
> manual says that would be Q4 on the solenoid/driver board.  I would
> think it would be the same on Centaur too.
>
> steve
> ---
> Steve Kulpa (cargpb10)

> Nolensville, TNhttp://stevekulpa.net/pinball/pinball.htm- Pinballhttp://stevekulpa.net/pinrepair/pinrepair.htm- Repairhttp://stevekulpa.net/faces/rgpidx.htm - Faces- Hide quoted text -

>
> - Show quoted text -

Steve, thank you for your thoughts on this.

The fuse blows on start up and the coil is never energised (locked
on).

I suspect the diode is bad on that coil.

I will replace it and report back when I get home from work tonight.

[AVP Pinball Division]

"cdnpinballer" <cdnpin...@hotmail.com> wrote in message
news:94175e94-06f9-4778...@r1g2000yqk.googlegroups.com...
>...fuse pops

You wired the coil backwards and the diode is permanently shorted. Cut the
diode, a common 1N4004, from the coil and replace it. When installing the
diode either look at the schematic or neighboring coils to determine which
wire goes to the banded end. Test the associated drive transistor. 50/50
chance of failure there. The fuse popping in this case may have saved the
transistor.

--
Pistol Pete
AVP Pinball Division
Towson, MD
410-583-9200
web: http://www.AVPpinball.com
email: ser...@AVPpinball.com

[Christina McGann]

An update.. Still trying to figure this out.

Changing the outhole kicker diode didn’t solve the fuse blowing but
did activate the coil in test mode, which it hadn’t before.

Then I tried clipping the voltage line to the ball trough and the fuse
wouldn't blow so I suspected the diode on that coil was bad so it was
changed and still the fuse blew.

I then realized there was a short between the coil voltage line and
the lamp bus wire but I cannot isolate where the short is. When I
unplug the solenoid expander the short is resolved so I suspected a
short within the expander.

I swapped expanders with a known good one and the problem still
persists. I am totally stumped other than there being a short in the
wiring harness. That will mean taking apart the harness and checking
each wire for damage.

A visual inspection of the coils, wiring harness, lamp bus, lamp
sockets all look good with nothing touching, I have looked it over
more than several times and cannot see any apparent visual shorts
anywhere. All coils have been checked and are wired correctly with
the diode band towards the voltage line (solid yellow wire).

Any advice is greatly appreciated.

[Hillcrest Express]

On Feb 22, 11:03 pm, Christina McGann <lifetreecounsell...@gmail.com>
wrote:

Was using my wife's account.

Also wanted to mention that I have a working Alltek MPU and SDB for
testing in the game and both test out fine in other games.

[LoveF2K]

On Feb 22, 11:34 am, cdnpinballer <cdnpinbal...@hotmail.com> wrote:

I would look for anything obvious that might be shorting somewhere.
After doing a swap, everything is moved around, especially bulb
sockets and the solder tabs. Make sure none of your coil lugs are
touching any metal. I just swapped an EBD and had the same problem
this past weekend. Pulled my hair out but never found anything wrong.
I did find a shorted switch but I don't think it was related. I put
the pf back on the table and looked it over and did see some wires
that looked like they could have been shorting. Maybe I just had a
coil that had a binding plunger that I freed up unknowingly. It seems
to working ok now and not blowing the fuse anymore.

Rich

[cdnpinballer]

Ok, some further developments on this problem.

I have isolated the short to be on the 43V line to the solenoid
expander shorting to ground.

There seems to be continuity between the 43V pin and the ground pin on
the solenoid expander.

Is this correct?

The 43V to the solenoid expander picks up power from the ball release
coil.

The incoming voltage to the ball release coil does not short out so I
can assume there are no shorts in the wiring harness or the power
chain before the ball release coil.

[Gott Lieb?]

If the diode on the ball kick coil is installed backwards or shorted,
there will be a 43v sol. bus short to ground when the sol. exp. relay
engages.

Also, if the cr1 diode on the sol. expander board (used for the relay)
is installed backwards or shorted, there will be a short to ground,
there could be a short between the sol. bus and ground.

Jim

--
Gott Lieb?

[dwagler]

Look to see if the jumper is installed on the solenoid expander board -
just fixed the same problem you were having and the solenoid expander
board had the jumper wire installed, and for Centraur, it shouldn't be.
I just clipped it with some wire cutters.

dave


--
dwagler

[cdnpinballer]

Problem solved! Woohoo!!!!

It was a short on the solenoid expander board.

Thanks everyone for the help.

[Blaine Sellie]

Did this require a new board or?

[John Robertson]

You are unlikely to get the answer to this 11 year old posting.

What is your problem that you need help with? Do you also have a lamp
that blows a fuse? If yes, check for loose lamp sockets that can short
out internally.

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
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"Old pinballers never die, they just flip out."

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