NTC MODEL: km-411 pincushon solved
- From: "yhan" <cheian07@xxxxxxxxx>
- Date: 15 Mar 2006 00:39:54 -0800
hi there again!
Could anyone help me out this monitor?
NTC, model No: KM-411
The problem is low width and pincushion. It also has slight breathing.
I checked diodes, and transistors in the horizontal and pinamp area but
not found the culprit. Check coils by substitution but still no effect.
Comparing the voltage from a known good monitor, I discovered that this
one has low B+ output. Measured from flyback primary winding, the good
monitor has 200 volts. But the defective one has only 170 volts.
Anyway, I have tested capacitors with my ESR meter in the psu and
horizotal. They seem okay. Disconnecting flyback primary winding creeps
up the voltage to 215 volts. Does it mean the problem lies on the
horizontal section and not on the low voltage power supply section?
Where should I look now. It seems I'm lost.
Thanks in advance for troubleshooting tips.
ian
Ps. Ive reposted it so that other who may ran same problem be helped a
lot.
I've already found the problem. It's the
flyback (LOPT). Substituted it by a known good one and the set was
fixed. I
just dont know why flyback fails this way. I guess its defective
internally. Maybe partially shorted or open. I am not sure. Its because
when i disconnect the B+ supply in the primary winding of the flyback
before the problem was solved, the voltages in the horizontal section
creeps up to 200 volts.
So if someone encounters this problem, NTC, Model No: KM-411, if after
checking yokes, capacitors esr and capacitance and other components
especially in the low voltage psu and horiz section reveals nothing, a
big chance its the flyback breaking down when under load.
.
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