Tandy 1000 SL Technical Reference Manual page 227

Troubleshooting
Equipment for Test Set-Up
Isolation Transformer(minimum of 500 VA rating)
CAUTION
Dangerously high voltages are present in this power supply.
For the safety of the individual doing the testing, please
use an isolation transformer. The 500 VA rating is needed
to keep the AC waveform from being clipped off at the
peaks. These power supplies have peak charging capacitors
and draw full power at the peak of the AC waveform.
0-28OV Variable Transformer (Variacl- Used to vary input
voltage. Recommend
5
amp, 1.4 KVA rating, minimum.
Voltmeter- Need to measure DC voltages to 50 VDC and AC
voltages to 300 VAC. Recommend two digital multimeters.
Oscilloscope- Need
x
10 and
x
100 probes.
Load board with connectors- See Table 1 for values of
loads required. The entry on the table for Safe Load Power
is the minimum power ratings for the load resistors used.
NOTE: Because of its design, this power supply must have a
load present or damaging =oscillations may result. Never
test the power supply without a suitable l o a d .
Ohmmeter
Set-Up Procedure
Set up as shown in Figure 1. You will want to monitor the input
voltage and the output voltage of the regulated bus, which is the
+5 output, with DVM's. Also monitor the +5 output with the
oscilloscope using 500 mv/div sensitivity. The DVM monitoring
the +5 output can also be used to check the other outputs. See
text of "NO output" section for the test points within the power
supply
Visual Inspection
Check power supply for any broken, burned, or obviously damaged
components. Visually check fuse, if any question check with
ohmmeter.