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After the schematics for the various circuits and sub-circuits were
complete, it was time to start reverse engineering them in greater
depth.
The circuit fragment shown here is part of the 110 volt injector
power supply circuit. IC 14 is an HC 7414 Inverting Hex Schmidt Trigger
wired to function as an oscillator which, in conjunction with 3
capacitors and 3 diodes, steps 5V up to 16V to supply power to a MOSFET
gate drive circuit.
The grey circles are solder dots 1.10mm in diameter placed as access
points for probing the circuit to test it. The numbers in blue are the
X-Y coordinates for the test points. Click on the coordinates to see the waveforms at that
point.
A database was made of the voltages, frequencies and waveforms
present at these test points.
As this database grew, it became very easy to identify problems
and repair any IDM that did not work properly.
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