TECH: Noise from Midway KICK
true...@netwalk.com
I recently purchased a Kick and it plays very well except for some annoying
noise as follows:
When I turn on the game, I get a moderately loud 60Hz buzz from the
speakers. The volume of this buzz goes down significantly (but does not
go away) when the coin door lamps are removed (remove one and it goes
down some, remove the second and it goes down more). The volume is not
affected by the game's volume control. When I disconnect all the wiring
to the coin door, the buzz volume stays about the same as when the two
coin door lamps are removed.
When I put a credit on the machine, the 60 Hz buzz goes away and is
replaced by a higher pitch "fluttery sound". This sound IS controlable
by the volume control but is loudest near the center volume setting
which is where I want to keep the volume when the game is playing. When
the game is over and goes back into attract mode, the "fluttery" sound
goes away and the 60 Hz buzz returns until the game is coined up again.
The problem seems to be at least partially attributable to electrical
interference from the 12V circuit that is made better or worse depending
on the amperage level (how else to explain the relationship to the coin
door lights).
This is not a big problem and I continue to enjoy playing the game but
would like to fix it if I could. Any advice appreciated.
-----== Posted via Deja News, The Leader in Internet Discussion ==-----
http://www.dejanews.com/ Now offering spam-free web-based newsreading
Rick Schieve
In article <6fpihm$ie7$1...@nnrp1.dejanews.com>, <true...@netwalk.com> wrote:
-I recently purchased a Kick and it plays very well except for some annoying
-noise as follows:
-
-When I turn on the game, I get a moderately loud 60Hz buzz from the
-speakers. The volume of this buzz goes down significantly (but does not
-go away) when the coin door lamps are removed (remove one and it goes
-down some, remove the second and it goes down more). The volume is not
-affected by the game's volume control. When I disconnect all the wiring
-to the coin door, the buzz volume stays about the same as when the two
-coin door lamps are removed.
-
-When I put a credit on the machine, the 60 Hz buzz goes away and is
-replaced by a higher pitch "fluttery sound". This sound IS controlable
-by the volume control but is loudest near the center volume setting
-which is where I want to keep the volume when the game is playing. When
-the game is over and goes back into attract mode, the "fluttery" sound
-goes away and the 60 Hz buzz returns until the game is coined up again.
-
-The problem seems to be at least partially attributable to electrical
-interference from the 12V circuit that is made better or worse depending
-on the amperage level (how else to explain the relationship to the coin
-door lights).
-
-This is not a big problem and I continue to enjoy playing the game but
-would like to fix it if I could. Any advice appreciated.
-
------== Posted via Deja News, The Leader in Internet Discussion ==-----
-http://www.dejanews.com/ Now offering spam-free web-based newsreading
Welcome to the wonderful world of Midway MCR games. There are just
WAY to many low level audio signals routed everywhere and WAY too
many overly long ground connections and ground loops. Combine
these things with old failing connectors and...
I'd really love to hear if someone has some standard fixes for the
type of problems described. I know I've wasted way too much time
trying to fix some of these problems myself. It's kinda sad that
my opinions on game are so clowded by my opinion of the hardware
that supports them. There was a time I enjoyed the various MCR
games but they all just look like headaces to me now.
Rick Schieve
sch...@lucent.com
Mitchell Rohde
Look, 60 Hz audio noises can't be that hard to pound down. It is a
question (as Rick probably knows, as he mentioned "ground loops") of
correct grounding and filters.
The first thing I would check it how the 60 Hz is getting in to your
audio. It may be just ripple you are hearing because of old dried out
caps in the power supply. Any cap that is suspect AT ALL you should
probably replace (ok, test it if you want... but out of circuit and with
a decent tester... sometimes, even this doesn't work and you need to do
something like a charge/discharge test).
In fact, if it's the output caps across the bridge you might consider
putting larger caps on than originaly designed!
I think the problem might be that many of you guys are replacing the linear
supplies with the switching jobs. Those switchers are prone to both high
frequency noise from the oscillators and 60 Hz noise because of isolation
issues.
Also, if the 60 hz is loud, it is probably getting in before the amp, and
low indicates it gets in by induction through the wires post-amp...
anyway, these are just rambles and thoughts. I will look at an MCR schematic
soon to figure out why there are so man problems!
Mitch Rohde