Rudy Trubitt, you wrote,
>I don't reccomend use of the Denecke PS-1 with Sony consumer DAT
>machines. I unwittingly blew up the mic inputs of my D8, I presume by
>putting 48 VDC from the output of the PS-1 across in input coupling
>capacitor in the D8 that is rated only to a few volts. I did the same
>thing to an SBM-1 before I realized what the problem was.
>
>Perhaps there is a sequence of connecting all the devices and
>inserting the battery to the PS-1 that would avoid the problem, or
>maybe a way to block DC from the PS-1 to the deck (transformer?
>coupling capacitors?).
>
>I haven't tried the two channel version, the PS-2, but I'd proceed
>with caution. It's too bad, I love the Denecke stuff, built like a
>tank and nice in the field. I have their InBox AD-20 also. I just
>found that the PS-box wasn't a good mate for my Sony gear.
I immediately went to the bench and made the following observations:
With the PS-1 microphone output connected unbalanced and unloaded,
i.e. pin 2 to voltmeter, pins 1 and 3 to ground, I saw a pulse of at
least 36V at the output when the battery was inserted. This decayed
to a few hundred millivolts. That pulse could indeed burn out the
input coupling capacitor of a consumer field recorder.
I saw a similar pulse when the PS-1 input was shorted to ground (pin
2 or pin 3 to ground) with the battery removed, shortly after the
battery had been in.
Any DC at the mike output is undesirable. I think it would be easy
for Denecke to limit anything above a few volts appearing at the mike
output, and I'm copying this message to them with the hope that
they'll modify the circuitry to eliminate this hazard.
-Dan Dugan
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