Keysight DSO9404A oscilloscope repair failure case

1. Instrument Model

Keysight DSO9404A Oscilloscope

2. Fault phenomenon

The oscilloscope cannot be turned on normally, and the startup screen flashes and then goes out.

3. Testing process

After checking, it was found that the oscilloscope had been disassembled, 2 screws were missing on the left side, and the acquisition board was missing screws. After disassembling the machine, it was found that there were obvious signs of desoldering inside. After testing, the instrument acquisition board had been repaired and desoldered, and the ADC unit of the acquisition board was damaged, causing abnormal startup; after startup, the acquisition board was not recognized, the fan speed was too high, and the acquisition board logic unit was damaged; the CH2 vertical encoder was damaged.

4. Maintenance process

Repair: Replace damaged components of the acquisition board ADC unit, replace damaged components of the acquisition board logic unit, replace the encoder, and adjust the detection instrument;

5. Repair results

The instrument starts up normally and the repair is completed.