Under cover overview small.jpg (attached) shows the TWC's visible main circuit board though there is another board beneath it. Based on an IR photo, the low voltage power supply seems to be in the upper left.
CNA1:
White wire connects to black 120VAC main line at 1.2ohm resistance.
Blue wire connects to red 120VAC main line at 1.3ohm.
This is the only place where power comes in to this board.
CNA3:
Left two wires (pin 1, 3) are ground
Right two wires (pin 2, 4) carry 12.5VDC when huge white relays at the top are closed to charge car. Otherwise they carry 0VDC. In this way, car charging relays automatically close if power is lost.
CNA6:
4 white wires lead into this 8-pin connector.
Top two wires screw directly to red 120VAC line but wires have "overload" resistance on the meter. I checked carefully and even plugged a pin into the female crimp on the wire to see there is no resistance between inside female crimp and back/sides of crimp.
Bottom two white wires screw directly to black 120VAC line and also have overload resistance.
Right wire in both sets is grounded.
I'm guessing this is some sort of safety mechanism. Maybe an overvolt or overheat will break down the resistance in these wires and do something useful.
BDA1:
DFL1508S bridge rectifier.jpg shows this bridge rectifier that converts two 120V AC lines to +135VDC on the "+" pin and -135VDC on the "-" pin. Top "~" pin connects to black 120VAC power source at 12 ohm resistance (not sure why it's not 1.2ohm resistance like other connections but I triple checked it's 12 ohm). Bottom "~" pin connects to red 120VAC at 1.2ohm resistance.
The green capacitor (or maybe not a capacitor since it seems to be labeled starting with an N instead of a C) measures 124VAC on both legs. Maybe a thermistor to limit current when it overheats?
In
Transformer area.jpg I've got a UV light showing some of the conformal coating edges. The clear, hard coating makes it difficult to test components covered in it, though I can usually find some tiny point that the multimeter probes can make contact. A few components have an extra-thick coating that makes them untestable.
At the far left is a FQPF5N90 MOSFET. Its S and G legs both measure -134VDC. D leg measures +144VDC.
CYA9 capacitor measures -134VDC on upper leg, CYA10 capacitor is tied to ground on lower leg, and other legs can't easily be reached. Near sunset, voltage dropped to -130VDC so it seems to vary based on the 120VAC house voltage which hits 126V at maximum solar power and 120V near sunset.
TA1 is the transformer with yellow tape near the middle. The transformer itself has no identification other than a "4" etched in the black metal to its lower left and "YC" etched in the black metal to its upper left (both visible in the pic but quite blurry).
The only test point in the area I can access is to the left of "CA55" and it reads 14VDC.
In
3.3v area.jpg UA23 is an 8-pin chip labeled 95M01WT K622K. I couldn't find that exact part number but
here someone asks about a 95M01WT-K430K chip and they decide it's an EPROM. Lower right pin is near an exposed test point that reads 3.3v.
Below UA23 is a ZXMP6A13 MOSFET that has no silk-screen label on the PCB. All its pins are inaccessible.
Another ZXMP6A13 MOSFET between the CNA3 plug and the white JTAG connector has uncovered pins I could test. S & G read 31.7VDC, D shows 0V.
A third ZXMP6A13 MOSFET at the top left of JTAG connector reads S and D 14VDC, G 3.3VDC using test points near the pins.
UA3 area.jpg has what looks like another ZXMP6A13 MOSFET but I can't read the chip label through its thick conformal coat and all its pins are well covered.
Left side of CA18 reads -14.66V. Remaining legs of these two caps are inaccessible.
More components I read inscriptions from with a magnifying glass and bright light, but didn't investigate:
LA7:
Inscription: G6161 02 ("02" is smaller with line over it)
Tiny black SMT (Surface Mount Technology) box. Assume it's an inductor based on LA label.
UA15:
Inscription: | 2903 SMT ("T" unclear)
Label style reminds me of ON semiconductor
UA16
Inscription: | NCV7356G (on) PXQH19
UA21:
Inscription: TMS320 F28034PNT G4A-5CACG6W G4
Largest SMT chip on front of board, has dozens of tiny pins.
XA1:
Inscription: H206E
4 pin, SMT
Metal body has 1.2ohm resistance to ground.