UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Looking for a Bench PSU. Suggestions please.

SiriusHardware · 16th Dec 2021, 8:35 pm

We have several generations of the Thurlby-Thandar PLxxx series power supplies at work, all are quite agreeable and the current limiting works as it should, it does not ever allow the output to provide more than the set current. The only problems I ever see on them are meter faults, often caused by failure of the CMOS switch IC (4066 etc) used on the meter circuit PCBs. Also the odd failed switch

We have some modern generic 'Tenma' branded 'digital' bench power supplies and the current limit is reactive, that is, it cuts in to limit the current only when too much current is detected, so if I set the output limit to 200mA and then short the output leads together, the initial zap, at 5A out, is enough to weld the leads together before the current limiting kicks in. Completely useless. If I'm trying to troubleshoot something which I suspect might be drawing too much current I go and get one of the old Thandars.

16th Dec 2021, 8:35 pm	#6
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,556	Re: Looking for a Bench PSU suggestions please. We have several generations of the Thurlby-Thandar PLxxx series power supplies at work, all are quite agreeable and the current limiting works as it should, it does not ever allow the output to provide more than the set current. The only problems I ever see on them are meter faults, often caused by failure of the CMOS switch IC (4066 etc) used on the meter circuit PCBs. Also the odd failed switch We have some modern generic 'Tenma' branded 'digital' bench power supplies and the current limit is reactive, that is, it cuts in to limit the current only when too much current is detected, so if I set the output limit to 200mA and then short the output leads together, the initial zap, at 5A out, is enough to weld the leads together before the current limiting kicks in. Completely useless. If I'm trying to troubleshoot something which I suspect might be drawing too much current I go and get one of the old Thandars.