Speakercraft DBB12100 Amplifier, Circuit problem

Yes, judging by the large picture of the back, clickable here...
https://www.referenceaudio.se/products/5661/speakercraft_mzc-66.aspx

and the decription...
http://www.soundseller.com/product_info.php/products_id/279

I'd say you can slave up to 12 audio channels off this thing. It neither knows nor cares what they terminate into.

You either have a shorted transistor or a cold solder connection at the output stage of the amplifier. The light indicates it cannot apply B+ to the circuit in order to prevent further damage or cause a fire. It needs repair - take it apart and inspect it for cold solder connections. If you cannot find any, take it to a repair shop and have them isolate the problem. Also, check the speaker terminal to make sure the + and - are not shorted together.

See link below.

http://www.pithed.org/2007/10/12/nad-c370-protection-circuit-repair-amp-fails-goes-into-protection-mode/

Protection circuit.
Checek the wiring of the amp and speakers, don' forget to look for shorts at the speakers. Make sure no wires are touching each other

Remove the load from the amplifier (subs) and the RCAs
Retry.
If the light stays on, there are internal problems with the amplifier, and it needs to be serviced.
If the amplifier works normally, attach the RCA's and power on again.
If it remains on, connect one sub, and then the other.
Your amplifier is a 2 channel amplifier rated at
60 Watt - 4 Ohm - 2 channel(s)
125 Watt - 2 Ohm - 2 channel(s)
250 Watt - 4 Ohm - 1 channel(s)
Your amplifier is not rated for a 2 ohm mono load.
If you have Single voicecoil subs wired in parallel, you have a 2 ohm mono load - your amplifier will eventually fail.

Does the amplifier do this when you don't have the sub hooked to it? If so, you have a pinch/short in your ground or power wire. If not, the subwoofer has a short in its voice coil or the amplifier needs to be repaired as it cannot handle a typical load.

What happens if you have the positive 12v wire from the battery connected?

If the protection LED is lit, the amp is in protect mode and probably has shorted output transistors. To eliminate other possible causes, read through the following page:

Amp in Protect Mode - Trubleshooting

Let me know if you have any other questions.

It probably has shorted output transistors. To eliminate other possible causes, read through the following page.

Amplifier in Protect Mode - Troubleshooting

Let me know if you have any other questions.

take the risk if you will attempt to change the voltage. but if your are willing to use the amplifier just take it to any authorized personels who knows. OK?