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bob orbell 14th April 2020 07:24 AM

PSU II & III transformer rating.
Can I ask for a little help, does anyone know the current rating of the above transformer and what is the current power consumption of the Phono II & III, thanks. Bob

Richard 14th April 2020 09:16 AM

Re: PSU II & III transformer rating.
1 Attachment(s)
Morning Bob,

The TX for PSU2 and 3 are shown as the same on both circuits - as attached.

The power consumptions of Phono 2 and 3 will be the same as both run 3 x ECC83. Running a Pre off the same PSU will make some difference as Pre2 and 3 were different and add load to the supply.

You can calculate the exact loadings by working out the consumption of the valves and dropper resistors used in any particular set-up. (Basically, if it's producing heat it's using power.)

bob orbell 14th April 2020 09:22 AM

Re: PSU II & III transformer rating.
Thanks Richard, and stay safe. Bob

bikerhifinut 14th April 2020 04:34 PM

Re: PSU II & III transformer rating.
Hi bob,
Well you'll Know its 1.5A heater draw for 5 x ECC8x valves.

As memory serves the current draw for the Phono is very low, not much above 5mA which a quick rough look at worst case circuit values confirms.

Again Pre 3 draws around 25mA so that's a total of 30mA on the HT.

You are using a Pair of ECC88 in your CF so You'll need to work out the current draw through the unit which I guess is ascertained from the cathode voltages on the bottom valves. I am not sure but I think the ECC88/6DJ8/6922 draws a wee bit less than ECC82/12AU7/5814 types which is a fairly current hungry device.

if I taught granny to suck eggs, sorry bob.

The WD transformer is rated at 2 A on the heater secondary and that's the reason I'm going to need extra heater amps when I knock up the 2 x 6SN7 line preamp as they are 600mA heater draw which takes the heater draw for phono and pre to 2.1A which might maybe perhaps be ok but it's going to run a bit 'ot! and not worth the risk.


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