MK Sound MX-125 MK II, V-75 MK II, V-125 Troubleshooting, MX-70B, If your Subwoofer has no output

powered subwoofers page 14

MX-70B:

The MX-70B gives a very high level of performance in a compact cabinet. Therefore, it is likely to be installed in both vertical and horizontal locations. To avoid having its inverted driver exposed in installations where the cabinet is horizontal, the MX-70B has two speaker grills.

If your MX-70B has a solid grille over the inverted driver, leave this grille in place. The MX-70B is designed so that the sound eminating from this driver comes from the opening in the front baffle. The solid grille cover insures that this is the case.

12. TROUBLESHOOTING

Your M&K Subwoofer amplifier circuit provides high reliability, and, if necessary, easy modular replacement of parts. This guide will help you to solve or diagnose most problems that can occur with your Subwoofer. In the event that a fuse blows, you must replace it with a fuse of the correct value to avoid a fire hazard and to maintain your warranty protection.

1. If your Subwoofer has no output:

a.Make sure that the Subwoofer is plugged into an AC outlet.

b.Check the "BASS LEVEL" control and make sure that it is set above the "MIN" position. Rotate it clockwise if it is set to the "MIN" position.

c.Check the red LED on the Subwoofer's back panel. If the LED is not lit, check the AC fuse next to the LED. Unplug the Subwoofer before changing the fuse. See instructions on Page 16. If the element inside the fuse is broken, replace the. fuse. If it blows again, contact your dealer or M&K.

d.If the red LED is lit, try this test: Turn the "BASS LEVEL" control to "MIN". Plug a standard RCA cable into the "FROM PREAMP" jacks. Lightly touch the plug at the free end of the cable, while slowly turning the "BASS LEVEL" control clockwise. If you hear noise from the Subwoofer when you touch the cable, the Subwoofer is functioning. Look elsewhere in your system for the problem. If you hear no noise, contact your dealer or M&K.

e.Make sure that the input cables are OK. Double check your connections. If necessary, replace any defective cables or speaker wires.

2.If, after operating the woofer at high volume levels for a long time, the woofer cuts out or becomes intermittent:

Your Subwoofer has a protection circuit that protects it from overheating. After hours of continuous operation at extremely high volume levels, this circuit may kill the power to the Subwoofer. When it activates, the sound may switch in and out rapidly, with a fluttering sound. If this happens, unplug the unit and let it sit for at least half an hour. After that time, plug it back in. It should operate normally. If you find this happens frequently, contact the factory for advice.

3.If you are using the "FROM AMPLIFIER" terminals, and the Subwoofer has very little output: