This is my favorite machine by far. There are machines with more tracks but the preamps and headphone amps make a good match on this one. And the pitch knob is really useful. You can get the 424s cheap and sometimes broken condition. Common fixable problems are A) that it wont turn on or B) wont play the tape.
A)If it wont turn on, if you have to find another machine that can turn on but has some other strange problems. the power section is very easily removed from both units ( even without soldering if i remember correctly). Swap the power supplies like I did in the pictures, WARNING some of these parts obviously store serious charges so give it a day unplugged before you go poking around in there.
B)Then my favorite fix is when the unit wont play the tape. Its so stupidly easy to fix. Open it up and there is literally a rubber band that will fall out of place from time to time. So easy and so common, this alone can put the unit in "as is" condition, saving you half the price.
Then finally if you must test the mix board without breaking out any instruments, you can use a patch cable from effect send one, and connect it to the 4 inputs on the mixer, turn the effect one send knob and watch the lights go up and down to your satisfaction.
Sometimes it will fail to record or playback form the tape, this is a problem of cheap tape, really cheap tape like the 120minutes low bias type. You need to use at most 60minutes or high bias type.
Another common problem is that these mixer lights stop working one by one, mine has no level indicator for track two.
Currently Im still kindof looking for a power section cause I broke it again by leaving the unit on all night while I fell asleep recording.
They've got one at my favorite local momnpop music shop. I didn't even bother to inquire the price, they go for $1000+ sometimes. It is amazing, there is about a dozen different ways to route with those few knobs. series, parallel, asyncronized, syncronized inverse, there is big difference in all the settings. my favorite part is the squarewave generator can get really slow and its not really square its more of a mutated sinewave with really long peaks and dips. this thing is great im sure its kind of annoying for audiences though.
So I think the TBD is one of the first big designs Devi Ever put into production. Now she has about thirty to fourty different designs. The TBD is kind of rival to the Zvex fuzz factory. It is an octave down fuzz with a blend control, a feedback loop with a photo eye and effect loop which you can insert other pedals.
