Bradley 233 - Servicing and Adjustments; General; Mechanical Details; Test Equipment

SECTION 5
SERVICING AND ADJUSTMENTS
5.1 GENERAL
Before attempting to trace a fault or effect a repair read the Technical Description given in
Section 4.
This section together with Section 4 is intended to provide the user with sufficient informa
tion to allow most repairs and to allow calibration of the instrument after servicing,
5. 2 MECHANICAL DETAILS
To remove the top or bottom cover remove the screw at each side and lift the cover off. To
remove a rotary switch, prise out the end cap in the small knob, slacken the screw behind it
and withdraw the small knob. Remove the larger knob. Using a box spanner, remove the
switch retaining nut. The switch can then be pushed backwards until the shaft clears the
front panel.
5. 3 TEST EQUIPMENT
1. Variac
2. AC voltmeter 3% accuracy. (Bradley Type 188 or 196).
3. Digital Voltmeter. (Bradley 173B or 188 or 196).
4. Oscilloscope 50MHz, 5mV/cm. (Preferably also ImV/cm).
5. Sinewave generator 0. 5MHz to 50MHz, lOV p-p max. (Tektronix).
6. Averaging counter capable of measuring periods, widths and delays of from lOnsec to
10 sees (if not available use oscilloscope).
7. Sampling oscilloscope with x 100 and x 20 high impedance probes (Tektronix ISl).
8. Two BNC cables 50fi ±2% approx. 4ft long.
9. BNC to "banana" plug lead.
10. Flexible leads Avith small probe clips.
11. xl Oscilloscope probe.
5. 4 POWER SUPPLIES (Test Equipment: 1, 2, 3, 4, 10 and 11)
1. Set mains selector to 200-250V range. Apply 220V. Switch on. Check that the power
lamp lights.
Select: Single cycle. Norm, +ve, offset zero on both outputs.
2. '+15V Supply-
Measure the voltage on the eyelet near TR422 with respect to chassis: , .
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