V1 12Au7 - Hammond XK-5 Service Manual

3.2.2 Adjustment and measurement point
3.2.3 Notes for operation of trimmer potentiometers
• Use flathead screwdriver which is fit to the hole shown in the figure.
(If Philips screwdriver is used, there is in danger of crushing the screw thread)
• The rotary angle is 240 degrees, so do not turn it more than that with force.

3.2.4 V1 12AU7

Set LEVEL to 0 on TUBE CALB2 screen and make the output of the test sine wave silent.
Measure the DC voltage of the vacuum tube side of C156 (T1U out) and C165 (T2U out) by
multimeter or the like, and adjust VR1 to set the both of the value around +15V (13V-16V).
The voltage is reduced when turning VR1 to the right.
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