My MXR Micro Amp started sounding wrong all of a sudden.I've had it for 7 months and never had a problem with it.It sounds that a busted speaker,or almost a fuzz know.I always keep the knob at 12 O' Clock.I checked all the resistors,and it doesn't look like anything's wrong.Does anbody know what might be causing this?
Off the top of my head... Did you clean the flux from the board after you were finished soldering?
Does anbody know what might be causing this?
Yepp, it's a bug in the microamp !
See "Debugging'' super-sticky.
...not too bad, simple...build another and compare !
Audio probe tends to point you in a much more specific problem related direction than 'bug in the amp', gives much more to work with.
Wiggle the board around ? Slightly bend-stress or push the wires 'in', or pull lightly. Tap-slap the box on all 6 sides in case something got lodged in there.
Quote from: soupbone on October 14, 2010, 05:10:01 AM
Does anbody know what might be causing this?
schemo (http://www.schematicx.com/schematic/mxr-m-133-micro-amp-pedal-schematic/)
- defective opamp (IC1)
- wrong bias (R7, R8, R2, C4, cold joint)
- interrupted negative feedback (R4, cold joint)
- defective decoupling cap (C1, C5)
- insufficient DC voltage (J3, D1, cold joint..)
- or maybe something completely different ;)
Measure DC voltages at all IC1 pins and post them here.
T.
Cool.Thanks everybody for your responses!I'll send you that info thomeeqe.
Hey Thomeeque,When you say measure the pin voltages from the IC,Do you mean measure the IC pin's to ground?
What should the voltage's read?
What should the voltage's read?
It is natural that they will read what they read.
An out of the ballpark reading would be good, unreasonable bias voltage would be a good reason for it not working.
The Sticky Thread: Debugging..when it doesn't work.
Read [and follow] that and you can help fix the Microamp.
Re-reading is also recommended.
Include freshly measured battery [with circuit load on it] or supply voltage so we have a reference potential with which to analyze the pin voltages with.
Quote from: soupbone on October 16, 2010, 04:26:48 AM
Hey Thomeeque,When you say measure the pin voltages from the IC,Do you mean measure the IC pin's to ground?
Yes :)
More debugging know-how here: DEBUGGING - What to do when it doesn't work (http://www.diystompboxes.com/smfforum/index.php?topic=29816.0)
T.