Performance Check; Equipment Required; Procedure - Polar Instruments TONEOHM 950 Service Manual

TONEOHM 950 SERVICE MANUAL

PERFORMANCE CHECK

Equipment required

•
DC voltage source, variable from 1V to 10V and accurate to 0.1%.
•
High tolerance resistors (0.5%) of the following values: 10KΩ, 1KΩ (serial numbers
below 005975 only), 200Ω, 100Ω, 1Ω and 0.1Ω.

Procedure

•
Switch on and allow the 950 to warm up for 15 minutes.
1. Plug in the Needle Probes and press 20V.
2. Apply 10V DC to the probes and check that the reading is 10V ± 4%.
3. Connect a 1KΩ 0.5% and a 1Ω 0.5% resistor in series.
4. Apply 10V to the series resistors. This produces 10mV across the 1Ω Resistor.
5. Press 20mV and check that the reading across the 1Ω resistor is 10mV ± 4%.
6. Adjust the voltage source from 0 to 20V and check that the tone varies in pitch. A
steady warble should be generated with a negative voltage.
7. Apply 1V to the two resistors and press 2mV.
8. Check that the reading across the 1Ω resistor is 1mV ± 4%.
9. Check that varying the voltage generates varying tones. No tone should be produced
below about 50uV.
10. Press 20KΩ and measure a 10KΩ 0.5% resistor. The reading should be within 4%. A
warble may be generated in this range.
(a) Serial numbers below 005975:
Press 2KΩ and measure a 1KΩ 0.1% resistor. The reading should be within 4%.
(b) Serial numbers 005975 up:
Press 200Ω and measure a 100Ω 0.1% resistor. The reading should be within 4%.
11. Press 2Ω and measure a 1Ω 0.1% resistor. The reading should be within 4%.
12. Apply solder to the wire ends of a 100mΩ 0.5% resistor.
13. Press 200mΩ and measure the resistor by pressing the probe tips into the solder.
The reading should be within 4%. Readings vary with the pressure applied to the
probes.
14. Press TRACE and connect the Drive Source leads across a 200 Ω resistor. Turn the
DRIVE SOURCE knob fully clockwise.
15. Hold the Current Trace Probe tip near to one of the Drive Source leads and align it
for maximum response.
16. Check that the display shows 20 or more.
17. Connect the Blue and Yellow Stimulus lead together. Press PLANE twice — check
for the warning bell and that the instrument returns to Standby. Leave leads
connected.
18. Connect the Red and Green Stimulus lead together. Press PLANE once. Check for
ACTIVE LED.
19. Connect the red and black Drive Source leads across a 0.1Ω resistor. Attach the
Plane Clip to the black Drive Source lead. Probe the other end of the resistor with the
probe.
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