Fluke 5720A service manual PA Supply Fault, 3612 +15 OSC Supply Fault, 3613 -15 OSC Supply Fault

5700A/5720A Series II Calibrator

Service Manual

Note

All of the following connections and measurements are done on the Filter/PA Supply assembly (A18) in order to verify operation of the +PA supply.

Connect DMM COM to TP203 and the high to TP201. Using a jumper, connect TP207 to TP203 and power on the instrument. The DMM should read +180V ±10%. Using another jumper connect TP205 to TP203. The DMM should read +360V ±10%. If either voltage is out of tolerance the Filter/PA Supply assembly (A18) is probably at fault. If the voltages are within tolerance, the Power Amplifier assembly (A16) is probably at fault.

3611 -PA Supply Fault

The +PA supply is set to +180V and +360V and measured at each setting to be within 10% of the nominal. Reset the instrument. Measure the logic level of TP205 and TP207 on the Filter/PA Supply assembly (A18). TP205 should be a logic high (8V) and TP207 should be a logic low. If these logic levels are incorrect the Digital Control circuit on the Power Amplifier assembly (A16) is faulty. If these logic levels are correct measure the +PA supply on the Filter/PA Supply assembly. COM = TP203, HI = TP201. The voltage should be 180V ±10%. If the voltage is out of tolerance, the Filter/PA Supply assembly (A18) is probably at fault. If the voltage is within tolerance, call up 200V via the instrument keyboard. The +PA supply should go the 360V ±10%. If the voltage is within tolerance, the diagnostic circuit on the Power Amplifier assembly (A16) is probably at fault. If the voltage is out of tolerance, check TP205 on the Filter/PA Supply assembly for a logic low before assuming the Filter/PA Supply assembly is at fault.

3612 +15 OSC Supply Fault

The instrument is dormant and the +15 OSC supply is measured to be within +14.2 to +15.8V. Measure the unregulated +15 OSC voltage on the Filter/PA Supply assembly (A18). COM = TP4, HI = TP2. The voltage should be +19V to +35V. If the voltage is out of tolerance, the Filter/PA Supply assembly (A18) is faulty. If the voltage is within tolerance, measure the regulated +15 OSC on the Regulator assembly (A17). COM = TP4, HI = TP3. The voltage should be +14.2V to +15.8V. If the voltage is out of tolerance, the Regulator/Guard Crossing assembly (A17) is faulty. If the voltage is within tolerance, the diagnostic circuit on the Oscillator Control assembly (A12) is faulty.

3613 -15 OSC Supply Fault

The instrument is dormant and the -15 OSC supply is measured to be within -14.2 to -15.8V. Measure the unregulated -15 OSC voltage on the Filter/PA Supply assembly (A18). COM = TP4, HI = TP5. The voltage should be -19V to -35V. If the voltage is out of tolerance, the Filter/PA Supply assembly (A18) is faulty. If the voltage is within tolerance, measure the regulated -15 OSC on the Regulator assembly (A7). COM = TP4, HI = TP5. The voltage should be -14.2V to -15.8V. If the voltage is out of tolerance, the Regulator/Guard Crossing assembly (A17) is faulty. If the voltage is within tolerance, the diagnostic circuit on the Oscillator Control assembly (A12) is faulty.

3614 OSC Com Ground Fault

The Oscillator Control assembly (A12) connects OSC COM to the SDL line where it is measured by the adc circuit on the DAC assembly for 0V ±50 mV relative to RCOM.

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