Re: Tech: Cheap Squeak Board Blowing C22 Capacitor
- From: m6onz5a <corvair@xxxxxxxxxxx>
- Date: Sun, 30 Dec 2007 06:44:43 -0800 (PST)
On Dec 29, 11:45 pm, AL <A...@xxxxxxxxxxx> wrote:
On Dec 29, 5:47 pm, Ken <jetsurg...@xxxxxxxxxxxxx> wrote:
Al Garber is probably the best source of info on here for Bally SS
machines. Hopefully he'll read this or contact him at: al <AT> team-
em <DOT> com
Wow Ken, Thanks. But I'm lucky if I can see the podium that the real
experts can stand on, let alone join them. I'm honored none-the-less.
Chas,
First off, the high voltage issue: You said you measured 230 VAC. If
that wasn't a typo, then there's something fundamentally wrong with
your meter or how you're using it. Let's just go with the asumption
of a spelling error. : )
At TP4, you should read 230 VDC (Regulator Input) and that will not be
affected by the adjustment of the potentiometer. The output is TP2.
This is the one that, by factory specs, should be adjusted to +190 VDC
under load. It is a common practice to lower this voltage (while
having someone else view the displays) to a point just abover strobing
or flickering to extend the life of the displays.
If TP2 does not change with adjustment, then I would say that Q21, the
current pass transistor is shorted or or VR1 or Q 23 open. These can
be measured with the game unplugged with the continuity (resistance)
setting on your meter.
The Blowing Cap ~ IIRC, that cap is on the board as secondary
filtration for the unregulated +12V line coming from the power
supply. I would suspect your issue stems from the supply and is not
on the sound board at all. Again, as speculation, I would assume
there is a short on the bridge rectifier and that passing AC is what's
blowing the cap on the board.
With the game unplugged, and the outputs of the power supply and
transformer input disconnected, you can measure the bridge rectifier
on the continuity setting of your DMM.
AL CARGPB 33(1/3)www.Team-EM.com
I just have one thing to say.... RGP is the BEST!!! Thanks for
everyones help.
I first tested the CORRECT test point on the driver board and brought
the voltage down to around 183 volts. I also retested the c22
capicitor afterwards and the voltage dropped to around 12vdc from
29vdc. I then grabbed my fluke multimeter this time and check the cap
for polarity. Installed it and I now have sound!!!!
I was a little disappointed on how simple the sounds are though. Just
a step up from EM chimes. I guess that's where the name "cheap squeak"
comes from..
Thanks again for everyones help.
Chas
Have a Happy New Year everyone!
.
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