STAR*TECH Journal
July 1995
. ... . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . .
HANTAREX
MTC-9000
PULSING HIGH
F REQUENCV SOUND
John Liikala
Canadian Amusements
Burnaby, BC Canada
Monitor
Proble1111s?
Order Th is Tech Pub
JVIONITORS:
SYMPTOMS/ SOLUTIONS
SUBJECT
Hantarex MTC-9000Colour 28"
monitor.
PROBLEM
When the monitor is plugged in,
there is a pulsing squeaking high
frequency sound,
like the horizontal
oscillator trying to
start up and shut
down repeatedly.
SOLUTION
The problem could
be one of many ca-
pacitors. C34 (22
microfarad @ 200
volts) may be open,
or C45 (1 microfarad @ 200
volts), or the B+ capacitor on the
neck board. The capacitor on the
neck board may be a different C
position but its value is usually
around 10 microfarad @ 200
volts.
and tum the power back on. You
will now notice that the squeak-
ing has stopped and no high volt-
age is present.
1990, 1991, 1992,
1993, 1994 & 1995
TESTING
Measure the volt-
age at either end
of the large power
resistor mounted
on the side of the
chassis. One end
approximately
161 volts, and at
the other end ap-
proximately 165
volts.
There
should be a differ-
ence of 4 to 6 volts DC. This
shows that the flyback has failed.
Another way to see if the flyback
has failed, is to measure between
the leads of the flyback to see
which pins are still connected to
each other.
FLYBACK PROBLEM
After testing several parts: IC2,
C35, TR14, the flyback trans-
former was found to be at fault.
There may be a little difficulty in
taking voltage measurements
- with the horizontal oscillator cut-
ting in and out. Therefore, shut
off the power, unplug the yoke
Includes all S* TJ
monitor articles from
0
0
0
0
0
0
1990
1991
1992
1993
1994
1995
$14.95
$14.95
$14.95
$14.95
$14.95
$14.95
Save over 30% order the
□ Entire set for $59. 95
Name:
--------~
Company _ _ _ _ _ _ _ _
I
Address - - - - - - - - - - - I
1
City _ _ _ _ _ _ _ _ _ _ l
State/Zip
CHECK
Also test to make sure that D27
is not shorted. In my case, the
diode was shorted and replaced
by a 1N4007 diode and pin nine
of the flyback was open from the
primary and shorted to pin ten
of the secondary.
I
I
I
I
Order O Prepaid or O COD I
(Please add $3 s/h. Thank you!)
I
I
STAR*TECH Journall
Post Office Box 35 I
.:'.:~f~~ ~ ~:. .2~°!.: J