Looking for help with Mitsubishi DA-A30 amp: one channel died during idling current adjustment without apparent reason. I’ve got this amp in a stock form a while ago and as always decided to do some upgrades. The Mitsu has four pots per channel, two for center potential adjustment and two for idling current. All old and single-turn; changed three pairs of them to multiturns. Powered on, amp seems fine, adjusted center potential as in SM, all good. Then went ahead to adjustments of idling current; for this, the SM asks to rotate both idling current pots counterclockwise, connect DMM between emitters of two output transistors, power the amp and first adjust VR104 pot to 20 mV, then wait and re-adjust it to 40-50 mV, then adjust VR105 to get 80-100 mV (see attached pic with description from the SM). Did it for the right channel, amp seems fine. However when I attempted to do same for the left channel amp emitted cracking sound and produced some smoke. The DMM showed 0 mV and the reading didn’t change with rotation of VR104 or VR105 pots; for right channel, it was around 1.3 V in the beginning but quickly went to 0 with VR104 rotation. Found that the PCB is charred at the R144 and the resistor itself is severely burned although still keeps 220 Ohm. Two other resistors, R145 and R184, also look burned but slightly and also are of expected resistance. Checked fuses-nothing blown. What could go wrong? The VR104 pot is at the base of Q110 and VR105 is at the base of Q118; R184-R144-R145 connect base of Q113 to +58V power rail. I’m afraid to turn the amp on and check voltages since something else could go up in smoking. Here is the link to schematics and Service Manual: http://www.vintageshifi.com/repertoire-pdf/Mitsubishi.php Thank you.