Thread: Psu iii mod
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Old 22nd March 2020, 10:08 PM
bikerhifinut bikerhifinut is offline
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Join Date: Jan 2006
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Default Re: Psu iii mod

Looks a bit like the choke "ringing" do you think? Or if its a "spike" at regular 100Hz intervals could it be switching noise from the bridge rectifier not being attenuated by the choke? And then exciting it at that frequency? One for John C or another with the necessary technical knowledge?

If its the PSU needing a minimum current draw then maybe trying a resistor across the unused HT output would help? Use ohms law and work it out as the value obviously depends on the voltage you are applying across the resistor. Not forgetting to do the ohms law power calculation for power rating of the R.

Might be worth a shot Bob?

What have you done instead of the choke between the caps on the C L C filter? I'd personally recommend a 150 ohm or if that's different to the DC R of the choke, a preferred value close to it to make a C R C filter which will reduce ripple far better than just a capacitor. For those not using regulated HT.

You shouldn't need a choke anyway if using a regulator on the HT as the regulator will ensure a steady, smooth voltage if its working correctly.

In the absence of a WD official kit for a regulated PSU, I'd recommend the Glassware (Broskie) Audio PCB kit, not cheap but its all top quality parts and a cinch to construct, adjustable output voltages using the table and resistor kit supplied. Assuming that in the current situation its available and there's still a transatlantic freight service.

Andy.
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