Informationen zum Rear Admiral ThunderDrive

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Power Supply
I have two original power supplies from CMD. One of them came with the CMD HD that I bought directly from CMD in the 90’s, the other came with another CMD HD that I bought secondhand. Both supplies are identical. The outside of the supply identifies it as an Autec “UPS 30-V20P” and the board inside is an Autec “UPS40-2002”. The supply has universal AC input and provides 5VDC @ 2.0A and 12VDC @ 1.5A.The output connector of the supply uses the same 4-pin DIN configuration as the 1541-II and 1581, with a small difference. The Commodore supplies have one GND and one NC (no connect) pin but the CMD HD supply has GND on both pins.

...The CMD HD supply can be used to power a 1541-II or 1581, but I do not recommend using any Commodore supply to power a CMD HD. Most 1541-II and 1581 supplies provide 5VDC @ 1.0A and 12VDC @ 0.5A. There is also a Commodore supply that provides even less: 5VDC @ 0.7A and 12VDC @ 0.5A. The exact power requirement of the CMD HD depends on the hard drive mechanism installed, but both of the Commodore supplies are rated for less current than the Autec supply. Another reason not to use a Commodore supply is that they are linear supplies that can cause overvoltage when they fail. The Autec supply that came with the CMD HD is a switched-mode supply that has overvoltage protection on the 5V side. Repair the original Autec supply or use a similar switched-mode supply with equal or greater ratings.