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Performed a forum search and was unable to turn up a schematic for this Line 6 Axsys amp I'm piddling with.
*Amp powers on but has a horrible buzz when the MASTER volume control is increased from infinity. Initially, there was no buzz when MASTER volume control was all the way down, now it doesn't matter whether the master is at infinity, or not. (keeping in mind the digital aspects of each control)
*Same buzz exists at the STEREO LINE OUT/HEADPHONE output, but at a much lower volume level.
* Performed hard reset first. No change.
*Using light bulb limiter: 1) bulb does not light with NO LOAD, and 2) bulb lights moderately with an 8-ohm dummy load connected to one output (no reason to load both outputs is there?)
* LM3886 chips get moderately hot when loaded, but temp is considerably lower with NO LOAD
* Replaced two open resistors, R20 and R21 (2.7 ohm), which are adjacent to the LEFT SPEAKER and RIGHT SPEAKER outputs, respectively.
* With ~39.5 VDC V+ at pins 1 & 5, both LM3886TF chips have ~0.5 VDC on pin 3. (measurements taken with unit connected to LBL, so voltages are low)
I'm inclined to button this thing up and cut my losses, but I thought I take a gamble here first. I don't want to start feeding this thing power amp chips without some expert advice.
Any suggestions?
*Amp powers on but has a horrible buzz when the MASTER volume control is increased from infinity. Initially, there was no buzz when MASTER volume control was all the way down, now it doesn't matter whether the master is at infinity, or not. (keeping in mind the digital aspects of each control)
*Same buzz exists at the STEREO LINE OUT/HEADPHONE output, but at a much lower volume level.
* Performed hard reset first. No change.
*Using light bulb limiter: 1) bulb does not light with NO LOAD, and 2) bulb lights moderately with an 8-ohm dummy load connected to one output (no reason to load both outputs is there?)
* LM3886 chips get moderately hot when loaded, but temp is considerably lower with NO LOAD
* Replaced two open resistors, R20 and R21 (2.7 ohm), which are adjacent to the LEFT SPEAKER and RIGHT SPEAKER outputs, respectively.
* With ~39.5 VDC V+ at pins 1 & 5, both LM3886TF chips have ~0.5 VDC on pin 3. (measurements taken with unit connected to LBL, so voltages are low)
I'm inclined to button this thing up and cut my losses, but I thought I take a gamble here first. I don't want to start feeding this thing power amp chips without some expert advice.
Any suggestions?
It's probably time to just screw this thing back together and find something constructive to do unless someone wants to chime in.
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