I got an old bench power supply, it's 18V 15A DC regulated adjustable voltage/current. Looks like it's almost a half century old, probably early 70s technology and uses SCR as the "switching" element - and hence this thing probably is fairly efficient compared to a series pass transistor design. Even after several amperes of low voltage use, this thing doesn't get that hot - its heat sink stays fairly cool.
However it seems to have severe overshoot when turning on from 0V. Anyone know what's normal for overshoot for SCR based PSUs and what to look for to deal with overshoot? Maybe this is normal though? Since SCRs can't be turned off until the cycle ends, it will overshoot, but by how much is normal/expected?
I need to test the capacitors in this system to see if any have rotted. The 70mF large capacitors unfortunately I don't think I'll replace so I won't check, but the small caps may have rotted over the years...
However it seems to have severe overshoot when turning on from 0V. Anyone know what's normal for overshoot for SCR based PSUs and what to look for to deal with overshoot? Maybe this is normal though? Since SCRs can't be turned off until the cycle ends, it will overshoot, but by how much is normal/expected?
I need to test the capacitors in this system to see if any have rotted. The 70mF large capacitors unfortunately I don't think I'll replace so I won't check, but the small caps may have rotted over the years...
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