- Taranis x9d+ with Crossfire bay module (removed for troubleshooting)
- radio will not power up
- worked through the main board regulator checks, including checking C64 (not shorted), L3 (not open circuit)
- checked R76 and R77 values (30kohm and 10kohm out of circuit which, though different from values posted elsewhere, appear to be the correct ratio).
- input to reg gets switched battery power but I only see 0.5v at the reg output (at C64)
I disconnected the main board from everything and checked the values again and they are no longer in a parallel circuit. Re-connecting step by step the issue appears to be related to a circuit on the back circuit board introduced by the P7/P8 ribbon cable.
I found some additional guidance suggesting checking the processor/regulator by plugging into the laptop via USB without powering up the radio. Initially this yielded nothing, and i was thinking fried processor or regulator, however i accidentally disconnected the P7/P8 ribbon cable and then got the beeps.
Probing the main board in this configuration, the voltage regulator is now working.
I don't plan to power up the radio in this configuration, but would appreciate any thoughts/advice where to check next. Is the parallel circuit formation meant to be there or is this a sign of a short circuit elsewhere?