Mackie 808S Powered Mixer Blows A Fuse

This powered mixer lives two lives; During the week, it rides quietly in the back of the sound van; When the weekend comes, it works hard as the sound system on the main stage for outdoor festivals. After years of incredibly reliable service, the unit just stopped. And it already had a date on the main stage at The Lonestar Rally in Galveston for the following weekend.  Could the Unbrokenstring Crew see what happened and bring this unit back to life?

This unit was cold and lifeless on the bench.  But where is the main AC line fuse?  We need to get inside.

 

Mackie is top of the line name brand, nearly ubiquitous is the sound reinforcement industry and in recording studios.

 

Name, rank, and serial number, please.

 

These screws hold the front panel in place.  The lock washers are captive.

 

We note that some of the machine screws are a different length.  This is noted in the notebook.

 

The screws in the back of the enclosure have large fender washers around them.  We note this, too.

 

The front panel is free.  Ah, but we are just getting started.

 

A large ground cable and a smaller white signal cable is seen in this view.  These are taped to the side to get them out of the way.

 

At the other edge of the front panel is this relatively fragile flat cable.  This requires special care as these are easy to damage and pinch.

 

Next, the power section of the unit is removed from the case.

 

This is what it takes to handle 600 watts per channel of audio power.

 

And here at last, at the very back corner, is the AC line fuse.  This fuse has fatigued over the years and finally opened.

 

The actual fusing element inside most cartridge fuses is a soft metal strip, suspended at each end.  They can fatigue and fail open, even under normal use.  I believe that this is what happened here.  The green tool is a real fuse installer.  Because I’m OCD like that.

 

There appear to be no other problems with this unit.  All the screws going back into the right places for testing.

 

 

So we tested the unit with a little Lennie Kravitz.

 

This unit has operated at full power for four hours, as do all of the finished repairs at The Unbrokenstring Shop.  I am deaf.

Thanks for reading all the way to the end!

CONTACT – David Latchaw EE
281-636-8626

 

Please follow and like us: