Using High Voltage Meter or Probe to Repair Equipment Problems Fast
A high-voltage meter or probe is the tool needed to
test high voltage circuit such as the picture tube of a Monitor and Television. Besides measuring the anode voltage of a cathode ray tube, it
can also be used to check the focus voltage of the flyback transformer. A normal maximum voltage a high voltage meter can check is about
30 to 45 kilo volts.
The ranges is marked in front of the voltmeter panel. Majority of our multimeter maximum voltage range is from 600
volt ac/dc to 1000 volt. Due to the low range of our multimeter whether an analog or digital meter is, it can’t test any voltages that is
higher than the maximum voltage or else your meter may becomes faulty!
There are some types of multimeter where you could connect an external probe which is specifically designed to
measure the high voltage of equipment. . In order to take the measurement, simply connect the high voltage meter ground cable to the chassis
or cold ground of the Television or Computer Monitor. Then, slip the probe tip underneath the flyback transformer anode cap. The high voltage
reading can be read from the meter’s panel.
I don’t always use high voltage meter to troubleshoot Monitor. I will
only use it when there is a symptom of no high voltage, high voltage shutdown, focus out problem, small and big horizontal size display. By
using only the high voltage probe I can tell at which section of a Monitor is faulty.
With this meter, it really saves me a lot of my precious time because
I don’t have to guess anymore which portion of a Monitor is giving problem. In Monitor troubleshooting, one of the most frustrated complaint
is the Monitor shut down when switch on. You do not know where to begin and if you are a beginner, you may take lots of time to troubleshoot
this type of problem. That’s why understanding how an equipment work is very important before you start to repair it.
Using this high voltage meter you could clearly see if the Monitor is
shutting down before it reached 24 kilovolt or after 24kv. If the Monitor shutdown when the voltage reached 15 kilovolt then you have to check
the horizontal oscillator circuit because the horizontal drive pulse was cut off when it reached 15 kilovolt.
All my concentration was upon this horizontal oscillator circuit which includes the surrounding components. After troubleshoot
for sometime I managed to locate a faulty resistor nearby the horizontal oscillator ic that turned into high ohms.
Assuming if the high voltage shutdown when it reached the 28-30
kilovolt scale then you can suspect the B+ voltage could be too high, internal flyback transformers capacitor value has became too low or open
circuit, safety capacitor (hold down capacitor) value run or open and suspect also the flyback transformer feedback circuit.
Many repair technicians and engineers confused about the section that
they going to check if there is a complaint of small horizontal width. A small horizontal width can be caused by two sections in a Monitor
i.e.; the B+ and horizontal size circuit.
If the picture horizontal size is small and measured only 14-18 kilo
volt with the high voltage meter then suspect the problem in the B+ boost circuit. It could be a defective B+ fet, dry joints, a missing gate
pulse to B+ fet, an open filter capacitor, a faulty current sense resistor or even a partially shorted B+ coil. A small horizontal size also
can be caused by a faulty horizontal size and s-correction circuit (circuit that controls the resolution width). Even though there are
problems in the horizontal size circuit, the high voltage will still maintain at 24 kilo volt. Thus, by using the high voltage meter I could
easily know which section is having problem and this will make my repair job a lot faster.
Testing the focus voltage of a flyback transformer can also be done
with the help of high voltage meter. With the help of this probe, knowing the focus voltage will easily tell if the focus out
problems was due to a faulty picture tube, flyback transformer or even the crt socket. Focus voltage is about 5 to 10 kilo
volts. Warning! Do not use your multimeter to measure it. Suspect a defective flyback transformer if the voltage that you checked rising after
the Monitor switch is ‘on’ for sometimes.
For a good flyback transformer, the focus voltage should maintain the
same even though the Monitor has switched ‘on’ for a very long time. Currently I’m using the Kaise-SK9000 high voltage meter probe that is
made in Japan. I’ve already used it for more than eight years and I can say that it is a very good meter and reliable too. Invest one if you
are in the Monitor or Television serving line and see how this high voltage meter can cut down your troubleshooting time.
Measuring The Focus Voltage