Shanda Williams
1/31/2011 12:16:00 AM
On Jan 29, 4:34 pm, Shanda 41 <shanda...@gmail.com> wrote:
> On Jan 29, 2:16 pm, "Dan Beck" <biscuitbecks@*NOSPAM*cableone.net>
> wrote:
>
>
>
> > "Shanda 41" <shanda...@gmail.com> wrote in message
>
> >news:9814f6a6-8ead-47c7-8997-340d11d0eb5e@q40g2000prh.googlegroups.com...
>
> > >I have a gottlieb system 80 b "Monte Carlo" pinball that keeps blowing
> > > the fuse on start up. The display just starts to light up and the fuse
> > > blows. This issue just popped up out of nowhere. I'm not as "seasoned"
> > > in gottlieb repairs as I am some of the others. Any thought's on
> > > where to start looking? If I disconnect the display the fuse is good,
> > > as soon as it's plugged in the fuse goes. (yes, I am shutting off
> > > power before removing the connector.)
>
> > > Thanks :)
>
> > Could you specify exactly which fuse you are blowing? Looking at a
> > different System 80B manual I see there are at least two fuses for display
> > voltage; 8.4 VAC and 32 VAC. If it's the 32 VAC I would put money on a bad
> > 1N4004 diode in the bridge rectifier circuit on the display pcb. The second
> > choice here would be the two Zener diodes on that circuit. If it is the 8.4
> > VAC line it may be a filament, as stated previously. One test would be to
> > put 12 volts DC across the 8.4 VAC supply and return line on the pcb, and
> > see how many filaments glow orange. On the 80B displays I have there are
> > four per single tube, or a total of 8 on the pcb.
>
> > Regards,
> > Dan
>
> Changed out the 4 diodes and we have power. I'll leave it running for
> a while and see what happens. Thanks for the help :)
So far so good, it's been running for about 10 hours with no problems.
Only 1 of them was bad but I have a bunch of the 1N4004's and they are
cheap so I just did all of them. The grounding mods seem to be working
too. I was having issues with the flash lamps locking on. They melted
the domes before they burned out.