Sub Is Not Powering On??

We assume that the amp powers up, and the horn tweeter still sounds when input signal is applied and the volume is turned up.

1. Turn off the power to the amp.
2. Remove the grille in front of the bass speaker. On this model, it can be pried off with an awl or the tip of a screwdriver.
3. Place the fingertips of both hands on the speaker cone, close to and on opposite sides of the central dome. Push the cone down very gently and evenly. The cone should move. There shouldn't be any scratchy noises or rubs. If there are, or the cone won't move, the voice coil is damaged or locked, and the speaker must be reconed or replaced.
4. Position the cabinet so that the front faces upwards. Remove the speaker from the cabinet. Remove the (usually) eight screws that hold the speaker and lift it out gently. You might need to pry the speaker out gently with the blade of a flat screwdriver because the gasket will tend to stick a bit. Disconnect the wires: these may be fitted with fast-on connectors that have to be gently pried off, or held with spring clamps. Note which wire goes where.
5. Obtain a single known good AA-size battery. Connect it to the speaker terminals. The speaker should crackle and/or pop when you connect and disconnect the battery. If it does not, the speaker is open-circuit. In some cases, this can be repaired at moderate cost, otherwise, the speaker must be replaced or reconed.
6. Obtain an old fashioned, mains powered incandescent light bulb, about 60-100W is OK. Connect it to the wires that power the speaker. Turn the amplifier on, apply signal and turn up the volume control. The lamp should glow. If it does not, the amplifier that powers the bass speaker has a problem. If the lamp glows with the volume turned all the way down, this also indicates a defective amplifier.

You should probably not try to service the amplifier yourself, unless you have ample experience in electronic troubleshooting and have access to at least a good multimeter and an oscillloscope.

The amplifier board in this cabinet has an integral switchmode power supply, which means that the board carries mains voltage, and the amplifier itself, being capable of several hundred Watts, also carries dangerous voltages. Don't mess with it if you don't know exactly what you're doing, 'cause it bites!