Hi Franc,
I am a newbie on this site. Can you give me details of the fcc site that has
circuit diagrams, as I could not locate it through google?Many thanks.
spd

Franc Zabkar wrote:
There is an IC that implement the power switch toggle effect. That is
where
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You're a walking IC encyclopedia?

4000 series CMOS logic has been around for decades. Anyone from the
old school would recognise that chip. BTW, I think that the R and S
inputs should be active high, not active low as I've drawn them.

AFAICT, the circuit looks like this:

[quoted text clipped - 25 lines]
the voltage by 1.5V doesn't help (use an ohmeter Rx1 range to short the
switch).

If you short the cap to ground, then the D input is always 0, which
means that Q will always be a 0. If you tie the cap to Vcc, then Q
will always be a 1 ... if the chip's clock input is working.

I don't know if it's a good idea to try to replace this chip. It's surface
mount and the chip is small (about 1cm) and the leads are even smaller.

Practice on a scrap board.

I'll play with this until I get tired of it. If I can not figure out the
definite cause then I'll just glue on an additional switch.

Being CMOS, and the fact that the chip is connected to the real world
(ie the switch), it may be that the clock input has been damaged by
ESD. (???)

I hope other LCD manufacturers are as nice as viewsonic in providing
circuit
[quoted text clipped - 7 lines]

Thanks for the info. I didn't know FCC has circuits in their database.

Neither did I until recently. Most circuits appear to have been added
after 2000. Not only that, but there are user manuals, block diagrams,
operational descriptions, and internal and external photos. They're
not always good quality, but they might be better than nothing.

One major downside is that the "searchability" of the database is very
poor. For example, I'd like to be able to locate all LG LCD monitors
for which circuits have been submitted. Or I'd like to find all ADSL
modems which use a Globespan Virata chipset. Maybe the FCC should let
Google manage their database.

- Franc Zabkar