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Siglent SPD3303D review
Zbig:
--- Quote from: FrankBuss on September 07, 2013, 11:25:12 pm ---And there is another big 4 leg IC on each heatsink, which has no label (doesn't look like it was sanded, just mounted the wrong way on the heatsink).
--- End quote ---
I think that would be the rectifier bridge.
FrankBuss:
I've done some scope plots for the problem on channel 3 and sent it to the support. It doesn't need to be a problem of the PSU in general, maybe my unit is just broken, but I doubt it. Maybe someone can verify it with his/her unit, if you have the same PSU?
I loaded channel 3 with an 8 ohm resistor, then I turned the PSU on with the power-switch (the PSU was turned off a few hours before). As you can see, there is a 1.5V spike, falling down over some milliseconds (1V and 1ms per division). The voltage selection for channel 3 was on 5V. If I turn it off for just a minute, and then on again, the spike can be even higher, I've measured up to 7V. There should be no voltage at all, because the channel is turned off initially when I turn on the PSU.
Same setup, this is what I see when I turn it off with the power-switch, and channel 3 still not enabled. A big 5V spike, falling over 100ms. And this is at 0,6A, because of the 8 ohm load. A sensitive DUT could be destroyed by it.
Same setup, channel 3 loaded with 8 ohm, the channel output was turned on with the CH3-ON/OFF switch, and then I shorted the output. As you can see, there are some serious overshoots, up to 12V! If I have a sensitive DUT attached and accidentally short the power supply outputs momentary, it could be destroyed by such overshooting. I don't trust this output at all anymore, because maybe there are some other overshoots, depending on the dynamic behavior of the DUT.
Just for comparing this with the other channels and to verify my measurements: same setup, but this time for channel 2 (8 ohm load, turned on). I shorted it momentary, as with the test for channel 3. As you can see, nice regulation without overshooting. Same for channel 1, no problems.
Zbig:
--- Quote from: FrankBuss on September 10, 2013, 01:13:20 pm ---I've done some scope plots for the problem on channel 3 and sent it to the support. It doesn't need to be a problem of the PSU in general, maybe my unit is just broken, but I doubt it. Maybe someone can verify it with his/her unit, if you have the same PSU?
--- End quote ---
As I have already reported in some SPD3303 threads before, I too have a voltage spike on CH3. I have SPD3303S HW ver. 1.0. It goes up to 12V on mine. I haven't tested the overload recovery overshoot. I can post some oscillograms later.
FrankBuss:
--- Quote from: Zbig on September 10, 2013, 02:05:12 pm ---As I have already reported in some SPD3303 threads before, I too have a voltage spike on CH3. I have SPD3303S HW ver. 1.0. It goes up to 12V on mine. I haven't tested the overload recovery overshoot. I can post some oscillograms later.
--- End quote ---
Thanks, so my unit is not broken. I hope they know a fix, or we have to reverse engineering the circuit and try to fix it ourselves :)
Hydrawerk:
I miss a numeric keyboard on this Siglent PSU. Even some old PSUs have it.
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