Testing Flyback Transformer-How to test and when to replace it
Nowadays, more and more monitor comes in with flyback
transformers problems. Testing flyback transformers are not
difficult if you carefully follow the instruction. In many
cases, the flyback transformer can become short circuit after
using not more than 2 years. This is partly due to bad design
and low quality materials used during manufactures flyback
transformer. The question is what kind of problems can be found
in a flyback transformer and how to test and when to replace it.
Here is an explanation that will help you to identify many
flyback transformer problems. There are nine common problems can
be found in a flyback transformer. a) A shorted turned in the
primary winding. b) An open or shorted internal capacitor in
secondary section. c) Flyback Transformer becomes bulged or
cracked. d) External arcing to ground. e) Internal arcing
between windings. f) Shorted internal high voltage diode in
secondary winding. g) Breakdown in focus / screen voltage
divider causing blur display. h) Flyback Transformer breakdown
at full operating voltage (breakdown when under load). i) Short
circuit between primary and secondary winding.
Testing flyback transformer will be base on (a) and (b) since
problem (c) is visible while problem (d) and (e) can be detected
by hearing the arcing sound generated by the flyback
transformer. Problem (f) can be checked with multimeter set to
the highest range measured from anode to ABL pin while (g) can
be solved by adding a new monitor blur buster (For 14' & 15'
monitor only.) Problem (h) can only be tested by substituting a
known good similar Flyback Transformer. Different monitor have
different type of flyback transformer design. Problem (i) can be
checked using an ohm meter measuring between primary and
secondary winding. A shorted turned or open in secondary winding
is very uncommon.
What type of symptoms will appear if there is a shorted turned
in primary winding? a) No display (No high voltage). b) Power
blink. c) B+ voltage drop. d) Horizontal output transistor will
get very hot and later become shorted. e) Along B+ line
components will spoilt. Example:- secondary diode UF5404 and B+
FET IRF630. f) Sometimes it will cause the power section to blow.
What type of symptoms will appear if a capacitor is open or
shorted in a flyback transformer?
Capacitor shorted
a. No display (No high voltage). b. B+ voltage drop. c.
Secondary diode (UF5404) will burned or shorted. d. Horizontal
output transistor will get shorted. e. Power blink. f. Sometimes
power section will blow, for example: Raffles 15 inch monitor.
g. Power section shut down for example: Compaq V55, Samtron 4bi
monitor. h. Sometimes the automatic brightness limiter (ABL)
circuitry components will get burned. This circuit is usually
located beside the flyback transformer. For example: LG520si
Capacitor open
a. High voltage shut down. b. Monitor will have