EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: daveyk on April 12, 2017, 12:53:07 am
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Hello,
I do not have a electronic load. What I do have is an instrument that runs on 11-16 volts and draws ~2 amps. When I use my Agilent 3632a above 14 volt in the 15 volt range, it de-regulates. It is okay if I go to 16 volts or above. I changed both pass FETs and the rectifier bridge. On the big main cap in the 15 volt range there is only 14.4volts so I can see why it deregulates around 14.2 volts.
12 volts AC feeds the bridge so shouldn't 20volts come out (12 *1.4 = 20)? When it switches to the 30 volt range the SCRs in the transformer circuit turn on and the cap voltage goes to about 42 volts. The power supply regulated fine on the 30v range as far as I can tell. The problem is on the 15v/7amp range.
There are two primary SCR circuits. One driven by "range" and the other by "tab". "Tab" seem to trigger at same time as the high range.
I'm scratching my head over this one. It should be simple. Can anyone tell me what cap voltage they have when on the 15volt range? When should the "Tab" controlled SCRs come on?
I'm tempted to jumper the "tab" controlled SCR circuit so it's on all the time.
Maybe a true calibration could fix this but I don't have an electronic load. I would like one but I don't expect to be working on many power supplies.
Thanks kindly,
Dave