Randall Amplifiers THRASHER 50 - Manual (Page 4)

Rear Panel Controls
MAINS SWITCH: Selects the country voltage.
For 100-120VAC selections, change IEC fuse to T5A/250V fuse.
For 220-240VAC selections, change IEC fuse to T2.5A/250V fuse.
The H.T. Fuse remains unchanged.
MAINS INPUT: AC wall power via included IEC cord to a grounded
outlet
HT FUSE: Protection for AC power faults.
CH/BOOST: TRS switching jack for footswitch,. Tip to ground
switching type. Tip=Channel and Ring=Boost select.
(2 button LED footswitch included)
LOOP: 1/4" tip to ground switching jack to bypass loop via
external switching unit or footswitch (not included)
TEST POINT & BIAS:
Using a Digital Multi Meter, set it to DC mV(olts) and insert the black probe
into the COMMON meter jacks and the red probe into either TEST POINT
meter jack.
Set MASTER volume fully counter clockwise and take the amp off
STANDBY, measure and set BIAS INSIDE 2 or BIAS OUTSIDE 2 located
below the test points. Adjust the bias pots slowly.
Please note that the reading is the sum of 2 power tubes. Factory settings
for 6L6 at either TEST POINT is 72mV, EL34 = 76mV, 6550/KT88 = 84mV.
T.5A FUSES: Fusing for the two inside pair and two outside pair of output
tubes. In case of output tube failure, only the problem pair of tubes will
drop out of circuit leaving you to finish your gig!