BMP finished, but weirdness happening

Started by lightningfingers, June 02, 2004, 04:12:26 PM

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lightningfingers

okay i put new transistors in my BMP clone, and all the voltages make sense now, and im pretty sure im getting the correct sound. but it only works at all if the sustain is on full, then literally 2 seconds after the initial attack this thing seriously craps out and the sound just goes splat then dies abruptly. i have no idea what is causing this but here are some part subs i made:

1000pf instead of 470pf in the input stage.
560pf insted of 470pf in the 1st clipping stage.
LEDs for clipping diodes in the 2nd clipping stage.

could any of these be causing the major crap-out?

i also noticed some oscillation at the highest sustain setting but i think thats normal for BMPs........
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petemoore

I don't think those substitutions will cause the symptoms you describe.
 Your description sound like 'gating', possibly a bias problem...what are the voltages you read...
 Audio probing also may tell you where the symptoms are stemming from.
Convention creates following, following creates convention.

lightningfingers

the voltages i got for the Qs were all the same, ~4.5 on the collector, 0.6-0.7 for the base, and 0 for the emitter.  Thats normal isnt it :?:  :?  :(
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sir_modulus

I'm not good at this stuff, but a 0V emitter doesn't seem normal. Shouldn't it be emitting something?