What is a FBT/LOPT Tester?
This little instrument identifies faults in horizontal output
stages by doing a 'ring' test, i.e. it applies pulses to the
line-output transformer/flyback transformer primary circuit, and counts the number of damped oscillations or
'rings' produced. For each 'ring' down to about 15% of the test pulse
amplitude, one LED in the 'bargraph' lights up... nearly all faults
will greatly reduce the number of 'rings' and give a very low reading.
It can be used on both monitors and TVs because it's not
frequency-sensitive, and the test signal amplitude is only 650mV- low
enough not to forward-bias semiconductors in the circuit.
To do a basic test, you connect the test leads between chassis and the
HOT collector... if more than 4 LEDs illuminate, the horizontal output
stage is probably OK. It can check LOPTs / FBTs out of circuit if
broken-down components prevent an in-circuit test.
It can't show up breakdowns which only occur at full operating
voltage, and it has no facility for measuring EHT voltages etc... but
then again it only costs a tiny fraction of the price of instruments
that can! In general it will show up about 80% of failures in
horizontal output stages, and is also useful for checking deflection
yokes, switching power supply transformers and other high-frequency
high-Q inductive components.
http://www.repairfaq.org/sam/flytest.htm
...Enter the
NEW Blue FBT/LOPT tester!
Measurement range: 0 to 8+ 'rings' of inductor/transformer under
test
Peak test voltage: 650mV
Power supply: 6V DC (4 x 'AAA' cells)
Controls: Push on/push off power switch
Dimensions: 2.7 x 5.2 x 2.2 inches (69 x 132 x 56mm)
Features
* Can generally test LOPT/FBTs in circuit, if no other components are
faulty.
* Also useful for testing deflection yokes and switching power supply
transformers.
* No fiddling with 'threshold' controls etc; readout is a clear 'bargraph'
display.
* Kit instructions contain a huge amount of information and hints for
using the
tester and diagnosing horizontal deflection stage faults.
The Blue
Ring Tester was designed by
Bob Parker
- ESR Guru. The unit is supplied either built or an an enjoyable
"home-build" project.
The kit includes:
:
