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Section 10 Troubleshooting
10-2
Reciprocal Shaking Water Baths
1. Be sure that the main power source is OFF.
2. Connect J101 and J105 to the POWER SUPPLY BOARD. DO NOT
connect J102 that comes from the CPU and the DISPLAY at this time.
3. Connect the negative lead of the voltmeter to TP2 - COM. Select a VDC of
20. Connect the positive lead to TP1 - UNREG.
4. Turn ON the main power.
5. The voltmeter should be reading approximately 14 volts DC, ±2.
6. Connect the positive lead to TP3 ±5V. The voltmeter should be reading +5
volts DC, ±0.5.
7. Turn OFF main power. Change the scale of the voltmeter to 200 VDC. On
later versions of the POWER SUPPLY board, there is a jumper JP1, located
near the transformer, that must be installed to measure the following voltage.
8. Connect the negative lead of the meter to anode (non-stripped end) of CR6
and the positive lead to the cathode (stripped end) of CR7.
9. Turn ON the main power and measure the voltage. The measured voltage
should be between 140 and 150 VDC.
10. Turn OFF the main power.
11. Connect the display board ribbon connector to the power supply board at
J102 and then repeat Steps 3 through 6. Do not connect the connector to
the CPU board at this time . If the above voltages are not measured again,
the display board has a bad component which is loading down the voltages.
If the voltages are still present, continue to Step 12.
12. Connect the display board ribbon connector to the CPU board J310 and
repeat Steps 3 through 6. If the above voltages are not measured again, the
CPU board has a bad component which is loading down the voltages. This
board will have to be replaced.
General Information: The POWER SUPPLY PCB ASSEMBLY #3176677 has
the triac (solid state AC voltage switch) on it which supplies the power to the
heater. This triac is "told" to operate, when need be, by the microprocessor.
There is another device known as an octo-coupler which serves as the high/low
voltage isolator between the triac and the microprocessor.
Thermo Scientific
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