Monday, March 5, 2012

Repairing a Hartke bass amp

Here's the story... right before Battle Toys first show, our bassist blew out the speaker in his Peavey combo amp.  We would have been left with no bass, luckily our friend and recording engineer, Chout, from the band Small White was able to loan us his Hartke bass head and cabinet.  The head has two 1/4'' outputs for speaker cabinets but one of them was busted.  I decided to thank Chout by repairing the outputs on his bass head... with his permission of course.

Front view



Holy crap, look at that monster transformer.  Also, you can see the two output jacks, just to the left of the fan.

I am a sucker for things that light up...


Speaking of lighting up... check out the glowing 12AX7 pre amp tube.  It's a little guy, but he gets the job done.  This head has the one tube pre amp, in parallel with a solid state pre amp, and a solid state output stage.

I wanted to get that header out of the board so I didn't have to hard solder the wires.  I tried to de-solder it, and pull with a needle nose pliers.  The board snapped, and luckily, out popped the header.  Woooooo!

Bloody Mary... because I don't need a reason.

Left:  Old and busted.   Right:  New hotness.  If there are any eagles eyes out there... you'll notice that I hooked the wiring up wrong on one of the jacks.  To quote Rick Perry... Oooops.  Luckily I ohmed it out before connecting it and discovered the problem.

Well, here ya go.  I connected the output of the Hartke to the 8 ohm speaker in that Crate amplifier.  Connected the oscilloscope to take a look...  Voila!  We have sound!  Both output jacks work!  All glory to the Hypnotoad!  

Oh wow... I just noticed all of the junk on the floor.  Is that a 3.5'' floppy disk?  What year is this, 1992?  


As always... questions?  comments?  Email me at soundularelectronics@gmail.com

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