#2 inverter on with usable power, but the #2 A/C annunciator would not extinguish.
Swapped cards 14X1 and 14X2, no help.
Swapped cards 401J and 402J, no help.
Swapped relays 4X1 and 4X2, again..... no help.
(Jumpseat removed to gain access to right junction area.)
Dropped overhead and shot switch, both contacts good.
(3X1 shown, 3X2 just to the right, but out of picture)
Pulled card 14X2 and grounded pin 6, annunciator went out. This proved that power through diode and card 402J was good.
Also verified that 115VAC and 26VAC outputs were good (at least with meter).
Swapped inverters (that were NOT in nose and NOT under rear cockpit floor, but behind the galley, major pain in the ass to find).
The problem followed.
Even though the #2 A/C bus was powered, the indicator showing 115VAC, and my meter also showing good voltage...... the inverter output did not satisfy card 14X2 as being good. Possibly an o-scope might of shown a signal problem, but this problem was quite perplexing because everything was showing to be good.