Andre Majorel writes:

On 2005-11-13, wrote:
On 2005-11-13, Andre Majorel wrote:

Last time I powered it, my Iiyama HA202-DT made a cracking
sound, similar to the sounds CRTs make when powered on, but
longer, louder and ominous. The screen is completely black and,
when fed a video signal, the monitor keeps "resetting" itself
every few seconds (the same "click" it makes when changing video
modes).

I suspect something in the high voltage circuit is blown but see
no obvious sign of damage. Any ideas ?

It sounds like the switching power supply is detecting an over-current
situation and is shutting down, then trying to restart itself again. I
would check the diodes in the secondary of the power supply and all
large transistors and diodes in the horizontal/high-voltage section.

Thanks. The rectifier bridge is rather well hidden but I checked
the semis on the left side. There is a big transistor (Toshiba
2SC5570, horizontal deflection output) with a dead short between
pins 1 and 3.

I don't have the schematics to check, but a short between the
base and the emitter seems suspect to me. Not that I'm an
expert, mind you.

B-E short may be OK if it's driven by a transformer. It's C-E short
that's guaranteed dead.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.