STD305M and a Linn Valahalla?

[LozR]

I have a STD305M turntable and a spare Linn Valahalla PSU, does anyone know for sure if it is possible to use the valhalla, probably in a separate box, to power the motor of the STD? The STD motor has 4 wires just like the LP12 and I think it operates on 110V AC so it should work but I don't want to ruin a good turntable without seeking advice first!!

Thanks in anticipation.

Regards L

[steve195527]

the Linn is a 24pole motor and the one in the STD is a 16 pole,the valahalla supplys the motor with a 50hz supply no matter whre you are in the world,does the motor in the STD receive its voltage at that frequency from the power supply fitted has standard?

[davidsrsb]

The STD305S motor has two quadrature 110Vac windings (actually wants 90V-ish) and the UK model is for 50Hz. I presume the 305M is the same, I believe the differences are mainly the plinth and only cosmetic.

[LozR]

Thanks for your replies.

The STD305M's power supply looks very simple consisting of a large resister and a couple of capacitors from what I can see so I believe that it runs synchronously off the mains frequency (50Hz in the UK).

Can I do any damage by wiring the Valhalla up do you think?

Regards L

[steve195527]

not sure,never owned or worked on a STD(we never sold those):-I'd email the folk who make the Hercules power supply and ask them if theirs is suitable for the STD,if it is then chances are the Valhalla is as well as its a direct replacement

[LozR]

Thanks Steve that's a good idea.

Regards L

[davidsrsb]

I forgot to mention the STD motor is rated at 3VA

[steve195527]

I forgot to mention the STD motor is rated at 3VA

doubt that loading would be an issue with any supply:-I would think the Valahalla would work fine but wouldn't like to say yes and then next post we read is it didn't and something got fried!

[davidsrsb]

I had a look at the Valhalla schematic on this site and now would not recommend it. For all the complexity, all it does is generate 85Vac for one winding and drive the other through a 220nF phasing capacitor (with a 68V zener + 12k shunt to guarantee harmonics).

This means the drive to the second winding is a different voltage and probably not 90 degrees out of phase. This is a crazy design, full of lethal voltages and one electrolytic going short away from putting 320V dc across your motor.

[steve195527]

I had a look at the Valhalla schematic on this site and now would not recommend it. For all the complexity, all it does is generate 85Vac for one winding and drive the other through a 220nF phasing capacitor (with a 68V zener + 12k shunt to guarantee harmonics).

This means the drive to the second winding is a different voltage and probably not 90 degrees out of phase. This is a crazy design, full of lethal voltages and one electrolytic going short away from putting 320V dc across your motor.

They seem a pretty successful power supply for all its design issues,never heard of one fry a motor,have heard of some components failing due to age/heat

[audioorigami]

have you got a picture of the motor in the std?

[LozR]

I have used an LP12 for a number of years with another Valhalla installed and it has worked reliably during that time but I am not really in a position to say if it is an improvement on the simpler original power supply, though others thought so when it came out.
The STD305M is sounding really well at the moment so don't want to ruin it but I can't help but think a better supply might lift it further.........
I don't have a photo of the motor but will take one and then see if I can work out how to post it here?
I do really appreciate everyone's comments and help.

Kind regards Laurence

[davidsrsb]

The immediate issue is that the Valhalla is a phase shift network design designed for one motor and the STD motor has very different inductance/resistance, so the phase shift is likely to be wrong. The Valhalla is set up for 85Vac, which is a lttle low for the STD.