Eminent Technology ET-2 Tonearm Owners

Picked up two of the medo pumps and pleased to see they are 50/60Hz, so proposing to run them in parallel off a step down transformer, as our mains supply is 230v. There was a suggestion to run two pumps out of phase with each other. What should I do with the earth wires, or should I leave them unconnected?
Any other advice for using these pumps greatly appreciated.
Regards
Grant

Hi Grant – welcome to the thread. Another New Zealander. I wish I was there right now.

With both Mark and yourself discussing Medo’s I dug out my medo ac0110 pumps from the past today and hooked them up separately and together to experiment. I remember I received them with three wires hanging. I cut off the three prong from two power cords and spliced them to make the wall plugs. So I did connect their grounds. I was only using one at the time and the other was a backup.

Separately mine both produce about 12 psi on a pressure gauge inserted within a few feet of tubing to the ET2. A real dynamo of a pump for only being a couple inches by a few inches.
When I connect them together on a T Valve PSI only goes up to about 15 psi as they are working against one another. Hopefully someone else can chime in if they are using two Medo’s. I went to the Timeter pump after the single Medo. The Medos are a linear piston design if that helps. Maybe Dover if he sees this can offer some advice as he used multiple pumps with his ET2 setup.
Cheers Chris

Hi Chris/Grant
Yes I used 2 pumps running into a 20 litre surge tank. On the pumps I used, reversing phase & neutral at the transformer inside reversed the phase on one of the pumps. In NZ you must not reverse phase and neutral at the power cord because the mains fuse must be in the phase line.

Hi Chris/Dover

Thanks for that information very helpful.

I have an ET2 with original low pressure manifold so I think 12 to 15 PSI if anything may be too high. The original pump did not like 50Hz, managing typically less than 4PSI.

Have filters and a pressure gauge, but not sure what a "regulator" is and locally what industry would be the best source for a suitable unit.

As the pumps are 115V, 50/60Hz I briefly considering running the two pumps in series, one "out of phase". I thought better to run them off a step-down transformer in parallel. Pumps would be housed inside a baffled box so effectively double insulated and isolated from one another, with the surge tank also housed in the same box.

For the surge tank I was going to use PVC pipe and fittings (2 - 300mm lengths of 200mm dia pipe with sealed end caps). Any advice on packing, was going to try some left over "BATTS".

Am I on the right track?

Many thanks for the advice.

Kind Regards

Grant

You've just reminded me - I got a big improvement when I put an isolation transformer between the mains and the pumps. Much smoother sound.