Definitive BP7006 Plate Amp – Powers On, No Sub Output (Need Help Diagnosing)

[SteveCHS]

Hi all — I’m trying to diagnose the plate amplifier from a Definitive Technology BP7006 tower.

Symptoms:
- The amp powers on (red light illuminated)
- No subwoofer output
- Main towers still play normally through my receiver
- No audible hum or noise from the sub section

What I’ve done so far:
- Verified fuse continuity
- Visual inspection: no burned parts
- Confirmed speaker driver reads ~5Ω DCR
- Board ID: LT-C126 (stamped on the PCB)
- Cap glue confirmed factory adhesive, not leakage
- Using a UNI-T UT210E meter (no capacitance mode)

Questions:
1. How can I confirm whether the problem is the amplifier board itself or the crossover / auto-on board?
2. Which voltages should I check first on the main board?
3. Any typical failure points for this model (BP7006) besides the small electrolytic caps in the preamp section?

Photos:
(I’ll attach pictures.)

Thanks for any help — I’d love to get this one working instead of converting to passive!