Star Tech Journal

June 1992
STAR*TECH Joumal
TROUBLESHOOTING MONITORS WITH
AN AUDIO GENERATOR
(PART 1)
Gary A. Hughes
General Coin Distributors
Portland, Oregon
The coin machine industry seems to create its own
seasons and times. Which means that some of us are
just getting around to Spring cleaning, and others
are putting the final touches on their Fall house-
keeping, and some are just getting around to the one
scheduled for February of '89.
SUBJECT
SELECTION
Part of the problem is that big pile of monitors in the
corner that aren't fixed but may be repairable.
Until we know for sure they will continue to take up
space and cost us time & money.
A usable generator should put out both sine anr
square waves, the sine being the one most used-
here. It should have a variable output from the
millivolts up to about 10-12 Vpp. A frequency range
ofl0 Hz to l00kHz is adequate, most will go higher.
My shop uses a Leader LAG-120B, which does a
good job. For your monitor bench, great sensitivity
and incredible bandwidth are not needed. If that
saves you any money it's good to know.
T'SHOOTING VERSATILITY
One of the most useful tools for your video bench is
an audio function generator, also known as a sine
and square wave generator .
Coupling this tool with
your trusty 'scope you can:
• Check electrolytics in
circuit
0
• Check flybacks in or
out of circuit
• Check entire horizontal
circuit in seconds
• Check diodes and
transistor junctions
• Decide whether to repair
or junk chassis before
you tie up precious hours!
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II D
Figure 1 Connections
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