19 Jan
2002
19 Jan
'02
3:58 a.m.
Ouch! What ever happened to user-replacable fuses to
handle such problems?
Yes *there is* SMD 500mA fuse and zener diode but that is AFTER that
darned ceramic capacitor. That why wall wart died and capacitor
started to cook again starting that stink when I tried to power modem
through that shorted cap.
Many transformers have thermal fuses designed to open
the primary circuit
under such conditions. If you can open up the PSU box, you may find a
replacable (with soldering iron and pliers) thermal fuse on top of the
transformer, or stuck under the tape covering the windings.
How diffcult to find this thermal fuse? This wart is hard to get
voltages w/ 16VAC. Most I see are 9, 12 and nothing of to find. I
had to make do w/ 12VAC for short term.
Don't be tempted to short it out, especially not
on something that runs
unattended like this modem. The next time the capacitor shorts, you might
end up with a fire...
Exactly. I have not seen *ceramic* go bad on low voltage unless
lightning did but this is in middle of winter in southeastern
ontario, no zeus lightning till summer. :-O Only time I saw one like
this was in panasonic printer and that was 12 years ago.
Some plastic cases have a conductive (Nickel-based?)
sheilding coating on
the inside. The HP thermal printer that's currently taking up most of my
bench does. Of course cheaper stuff tries to get away with no shielding :-(
Yes, that's right, nothing of this sort. Basically unpainted
grey plastic shells. Oh, Good Thing, maker forgot to put seal
sticker to bar me from cracking open that modem. >:-D
-tony
Cheers,
Wizard