Thanks for the input guys! So far I have only tried with the 303 on batteries, I don't have a PSU handy (which begs the question of whether there's one easy to buy here in Germany where I will be for the next few months)
I'm fairly sure the periodic buzz on the output comes from some sort of led driver circuit. It might also have to do with the clock circuit, as someone suggested. I'll check for broken traces around the output. That could be it, the output is completely dead, but the schematic shows both headphone and line outputs are driven by the same circuitry, so if the parts driving the line output were dead, the headphone output would be silent also I understand. I will try shorting out R47 to see what happens to the range. Would I have to change the vcf range trimpot too? Currently it's at nearly the lowest setting. Cheers, D. On Tue, Aug 3, 2010 at 03:58, Amos <[email protected]> wrote: > you might start by measuring continuity from component to component. > 303s get cracked traces often; their circuit boards are made of flimsy > stuff. > As for various mods go to the x0xb0x wiki or forum and you'll find plenty. > > On Mon, Aug 2, 2010 at 9:51 AM, cheater cheater <[email protected]> wrote: >> Hi guys, >> my TB-303 has some problems and I thought I would ask around if anyone >> knows how to fix them :) >> >> 1. line output not working >> yup :( no output. There is "perfect" output from the headphones output. >> >> 2. headphone output has a faint sound of digital buzz >> When the LEDs are blinking, I can hear a buzz when the LED is on. This >> might be the way it worked out of the box - but if so I would like to >> fix it with some mods. The sound is fairly prominent and can be heard >> when the synth is playing as well, making it useless for what I want >> to do (i.e. put the 303 stems in a mix not obscured by a lot of other >> sounds. I understand you wouldn't hear that in a very busy mix) >> >> 3. power-on thump >> I assume this needs some replacement of the electrolytic caps, but not >> sure which ones exactly. I wouldn't want to just go wild on it and >> replace everything >> >> 4. decay knob doesn't do anything >> No idea why. This started recently. >> >> 5. (hopefully a mod exists for this) the filter cutoff range is too >> small. I know you can change the range around a bit with one of the >> trimpots, but that doesn't give me the needed range. I would like to >> go from around 30 Hz to 30k if possible. >> >> 6. Potentiometers are noisy and slow, i.e. difficult to drag: >> the resonance knob is especially slow! The others feel a bit wonky too >> and are probably quite worn. Is there a good replacement? >> >> 7. Waveform switch is wonky and sometimes doesn't close contact properly >> is there a direct replacement part - or do I need to open it up and >> recondition it? I would really like to avoid that :X >> >> BTW, is there a mod to change patterns in write mode? >> >> Thanks a lot, >> D. >> >
