5
Aguilar DB750 Hybrid Head
Diagnostic and Protection
The DB750 is equipped with a self-diagnostic and status/protection circuit. Upon power-
up the unit’s blue status LED will blink for approximately 45 seconds. During this time
several circuit parameters are verified, or allowed to become self calibrated.
1. The high B+ voltage to the preamp tubes is slowly ramped up, allowing the tube
heaters to warm up before full current us drawn by the valves.
2. DC offset at the amp’s output is monitored. Only if none is present (normal
condition), will the unit proceed with the self-check protocol.
3. Temperature on the MOSFET heat sink is checked, and again only if normal
temperature is detected, will the status check to continue.
4. If all the voltages, offsets, and temperature are in accordance with factory
specifications, then the amp’s input, and output relays will be energized. This will then
cause the operate LED to illuminate and status LED to stop blinking, and the amp is now
ready for normal operation.
5. Continues monitoring of the above parameters, protect both the DB 750 and speakers
connected to the amp, in the event of unit, of user error. This will be indicated by the
status LED’s blinking.
6. If the status LED continues blinking, or starts blinking during amplifier use, this
indicates a system fault. The amplifier requires servicing in order for normal operation to
resume.
