On 2017-Dec-24, at 10:27 AM, Rob Jarratt via cctalk wrote:
I am continuing work to reverse engineer the schematic
for my H7826 PSU. I
have removed one of the daughter cards in order to draw its schematic, but I
can't identify some of the surface mount components on it. I have posted a
picture of it here:
The ones I can't identify are:
1. The component with two wide pins that looks like an IC
approximately in the middle of the board. It is marked M106 (or it might be
AA106) and 91813 underneath. I think it may be a resistor, but I am not
2. Just to the right of this is another much thinner two-pin component
which is black on top with a kind of white notch. I have no idea at all what
3. The three 3-pin black components to the left of the first
component. Two of them are marked "2T L" (or is that "ZT L"?), one
to be marked "2X I" (letter "ih", not letter "el"). I guess
transistors, but they may not be of course, and I don't know their pinout.
Any help with identifying what these are would be very helpful.
SMD codes are a mess as the same code is often used by different manufacturers for
Resolving them is often an effort working between the multiple code possibilities, what
makes electrical sense after reverse engineering the circuit topology, and ohmmeter
measurements of the device.
2: Try measuring the resistance, if it's a low resistance perhaps a fuse as Chuck
suggested, but considering the precision reference on the board, if it's a higher
resistance perhaps a precision-trimmed resistor.
3: As per Chuck's suggestion likely bipolar transistors, and probably:
with pinout (hopefully this renders unambiguously):
Try drawing it out presuming the above and then assess whether it makes sense electrically
for polarity, current flow and control.