Teardown & Repair of an Agilent E3631A 6V/25V 80W Triple Output Power Supply

In this episode Shahriar investigates a faulty Agilent E3631A 80W triple output power supply. The instrument powers on, display a fully illuminated VFD display before a long beep and dark screen. The disassembled unit reveals a two board construction. After an unfortunate finger burning experience, the fault is traced to pair of extremely hot voltage regulators and Zener diodes. The temperature of these components is measured using a thermal camera and reach 400C! The schematic of the power supply is examined and the appropriate components are replaced. The performance of the unit is verified after the repair.


  1. mehmet says:

    hi, my device shows values ​​when voltage and current are not set. as soon as the outputs are open, it shows current and the voltage moves constantly. I couldn’t find the defective part, can you help me?

  2. Daniel says:

    Great video! Since a long time i am looking for a reasonably priced offer of this power supply on eBay but can’t seem to find one. I rarely find broken units and working ones are at least 500 EUR. Am i just unreasonable in my price expectation? Do you have any hints on where else i could find one(shipping to Europe)?

  3. Mark J Rutenberg says:

    Very nice with all the explanation!

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