[dhp]

ok, so I was listening to my PINT, and everything seems fine, batteries are running low, so I decide to plug in the wallwart 24V 500mA adapter into the charging circuit. Sounds, good, then about 5 minutes later, everything turns into static as I think What to myself and turn the thing off. I breath a little, turn it on again and everything sounds perfect again (even after plugging in the adapter again). I measure DC offset from IG to OR/OL and it's <1mV. Good, GOod, then from IG to OG it's freaking >1V. ??? My ground opamp isn't dead though, so is there anything I do about this? Or is my ground opamp doomed to die a horrid death?

 

[dhp]

ok, after talking with [AK]Zip a little bit, it seems that it happens when you plug in the PSU while the amp is still on. Any insight into why this is? (tangent, amb, morsel, and any other deities of DIY?)

 

[amb]

If there is 1V between IG and OG then the ground channel is definitely not healthy.

I am usually a bit uncomfortable about plugging in the wallwart charger while the power is on. The supply voltage to the opamps increases a bit as you do that (from the batteries combined voltage to the 24V of the wallwart, minus one diode drop). However the increase is not necessarily smooth and gradual. The act of plugging in the barrel plug could "glitch" in that the voltage is spikey for a split second (probably much more than the power switch would), and might in theory upset the opamp(s).

 

[tangent]

Also, Team Mini3 has demonstrated a greater tendency toward oscillation at higher supply voltages, in certain situations.