All necessary voltage readings are given on the schematic. If either of the No. 55 Pilot Lamps under the Socket Panel fails, both lamps must be replaced at the same time with a No. 55 type only.
The A.C. line fuse is located on the Socket Panel. Replace only with 1 Amp. fuses of the same type.
During the following adjustments push button marked "Circuit Transfer" must remain in the UP or Jet-Check position.
Shorts Sensitivity Adjustment
To adjust Short Lamp Sensitivity, connect a 1 Meg. resistor from pin 2 to pin 4 of socket No. 1. Adjust R-16 while the Short button is depressed, until the Short Lamp just lights. R-16 is accessible with a screwdriver from the top of the panel through the center of socket No. 30. Remove resistor . Short light should then go out.
Grid Emission Sensitivity Adjustment
The sensitivity of the grid emission test circuit is adjusted at the factory so that a leakage of 25 Megohms just reads in the "Grid Emission-Reject" area on the meter scale. This order of sensitivity is the level that tube manufacturers recommend, in order not to reject good tubes.
To adjust the Grid Emission Sensitivity, connect a 20 Meg. resistor from pin 1 to pin 7 of socket No. 1. Adjust R18, while the Grid Emission button is depressed, for a meter reading of 20 on the numbered scale. R-18 is accessible with a screwdriver from the top of the panel through the center of socket No. 33. Remove resistor. Meter reading should then fall to zero with nothing plugged into panel.
If you wish to make the Grid Emission test more sensitive, use a 100 Meg ohm resistor in place of the 20 Meg ohm resistor as stated above.
Signal Voltage Adjustment
To calibrate the instrument for the proper signal voltage, connect an A.C. VTVM to pin 1 of socket No. 1. Connect the ground lead of the VTVM to pin 2 of socket No. 1. Adjust R-20 while Test 1 button is depressed, for 1.5 volts R.M.S. R-20 is accessible with a screwdriver from the top panel through the center of socket No. 25.
D.C. Bias Adjustment
To adjust for proper D.C. Bias, connect a 20,000 ohm/volt meter pin 1 and pin 2 of socket No. 1. Adjust R-11while Test 1 button is depressed for -2.5 V.D.C. R-11 is located beside the 6BN8 tube on the transformer bracket.
Balance Control Adjustment
To adjust R-5, connect a 6000 ohm, 10 watt resistor from pin 5 to pin 2 of socket No. 1. Set Sensitivity Control to 100. Adjust R-5 (while Test 1 button is depressed) for zero reading on tube tester meter.
R-5 is located on the rear of the transformer mounting just behind the power transformer.
Calibrating the B&K 707 is a pretty straight-forward procedure. Here are just a few of my personal tips.