“Maintenance Case” Agilent 6574A programmable DC power failure maintenance

Repairing unit: a certain group Co., Ltd. Xi’an Company

Instrument: programmable DC power supply

Brand: Aglen

「维修案例」安捷伦Agilent 6574A可编程直流电源故障维修

Type: Agilent 6574A

Failure description: After the machine is turned on, the front board is not displayed, only the fan rotates. Unable to operate and cannot be used.

「维修案例」安捷伦Agilent 6574A可编程直流电源故障维修

Test barrier:

Power up, detect the input power part, measure the high voltage at TP1 on the A3 board, TP2, 300V+, which is normal.

The input power is normal, and then detect the auxiliary power supply part, measure several test points of the A3 board auxiliary power supply part ( +5V, +15V

「维修案例」安捷伦Agilent 6574A可编程直流电源故障维修

(3) ,,-15V), as shown in the figure. Results+15V and -15V performed normally, only+5V voltage, only about 2.5V.

From then on, he started to check.

「维修案例」安捷伦Agilent 6574A可编程直流电源故障维修

This voltage is provided by a voltage pressure module, which is not normal to measure its input.

The input of this module is controlled by another voltage control chip. Measure the input of the chip

Output is not normal.

In order to determine whether the problem is from the A3 auxiliary power supply part or the influence of the rear -class circuit, disconnect the lines of the A3 board and A5 board, and then

Several voltage values ​​in the previous measurement, at this time the+5V performance is normal. It can be seen that the rear circuit affects this.

The problem was transferred to the A5 board, and the key investigation on the A5 board was investigated. After measurement and testing, it was found that there was a voltage control chip performance

「维修案例」安捷伦Agilent 6574A可编程直流电源故障维修

Suspicious, after the measurement of online measurement, it can be determined that it has been damaged, and the voltage that should not be exported to the surrounding chips cannot be output.

「维修案例」安捷伦Agilent 6574A可编程直流电源故障维修

As a result, multiple chips cannot work normally, which affects the front circuit.

After replacing the voltage control chip, the measurement of the A3 auxiliary power supply has performed normally. But at this time the instrument was still not displayed.

So look at the front panel control and display part. Detect the previous A1 board, there are U6, U3 and other chips to perform abnormal performance, isolation measurement,

Diagnosis U6 has been damaged,

After replacement, U3 continues to perform abnormal,

「维修案例」安捷伦Agilent 6574A可编程直流电源故障维修

Replace the test again, and the output of the test is normal.

At this point, the machine can be displayed normally after booting, the initial performance is normal, the panel can be operated, set a voltage value, try to lose

Out, get the correct output and display. At this point, the whole machine is repaired.

The above content is provided by the Antai Instrument Maintenance Center. For more relevant instrument maintenance knowledge, welcome to visit Antai Instrument Maintenance Network, follow the public account: Antai Test

Author: ArticleManager