Hi,

I have deassembled a surveillance camera containing a sharp ccd with
ir3y48a1 and lr38603a chipset. These cameras seem to have been popular
a few years ago, and are still sold as reverse cameras with LCD
monitor in many online shops.

I am looking at the input of the mc34063 voltage regulator mounted at
the same side as the lens itself. (Complete dissassembly). Between the
12V pin on the connector to car battery and the pins 6,7 and 8 is a
fairly large (for SMD) black component with two leads and "100"
printed on the top. It does not look like an SMD capacitor, and
measuring it with an ohmmeter give open loop. There are two other such
components on the board and they measure around 2 ohm, but I do not
know what is in parallel to those two other components. The PCB looks
like it is 4 layers and the traces are not easy to follow.

I try to find out what kind of component this "100" box is.

I have debugged the camera unit up to the video input. If I apply a
composite video signal (those that typically run down yellow wires or
plugs on TV sets) to the video input of the 2.4GHz radio transmitter,
I can see video on the TFT monitor. (This is RF bound signal
transfer). This means that the wireless part of the camera is working.
I measure the voltage out from the video output of the ir3y48a1/
lr38603a combination and the dc-level is 0, and the TFT monitor is
black. (not noisy like RF is when there is no carrier or lock). The
camera seems to have stopped working after a connection to the battery
where the banana clip lost connection. These MC34063 chips seems to
occupy a fairly large percentage of 12V powered car equipment, so they
must be either cheap or reliable or both.

I have not measured on the camera with power on so far as there is a
great chance of slipping with the probes and short circuiting
something else. Currently I am just inspecting and doing simple
resistance measurements on the power lines. I do measure open loop
between pin 6,7 and 8 and 12V so I suspect that "100" thing to have
died.

Besides, I discovered that whoever made that design decided to skip
the Rsc resistor which is mentioned in all datasheets and application
notes between pin 8 and 7. 6,7,8 are shorted by a piece of pcb track
between the pads. Could be that they have placed the Rsc in series
with the voltage input. I found the suggested capacitor between ground
and pin 8.

Now if anybody has experience with these cameras or have a suggestion
to what that "100" thing is, I would be happy to exchange more info.

--
Svenn