ReK O Kut conversion from 60hrz to 50hrz

[Simon]

ReK O Kut conversion

As I live in the UK 240V 50Hrz and I can not find a step down transformer that converts the Hrz back to 60.

I am thinking of scrapping the turntable after I rebuilt the motor last week.




I was think about using a Direct drive turntable like an old Garrard 401, as there are a lot of refurbished ones in the UK.

45, 33, 78 rpm speeds with pitch control.



http://www.slatedeck.com/For%20Sale%20Garrard%20401.html

Then mount the carriage onto a custom plinth.

I could also convert the platter to accept a drive pin.

Any objections or ideas would be great.




Or I could just use a Technics 1210

[dmar]

I was think about using a Direct drive turntable like an old Garrard 401, as there are a lot of refurbished ones in the UK.

401s are not DD turntables, they're idler-drive. Expect to pay a hefty chunk for one, also, since they've been an audiophile 'hot item' for the last few years. Especially if it's been rebuilt.

I'd suggest finding a Lenco, which used to be cheap and plentiful, but those are getting more expensive and scarce by the minute as well. Damn 'audiophool' market.

[Simon]

But surly the Rek o Kut is just the same

It has a Idler drive that runs on the inner side of the platter.

If you are talking about the Lenco Goldring 88 then there is no pitch control to compensate for the drag of the REK O KUT central drive unit.

[Tron]

I remember ALAN from the PRESTO history page had a Hybrid photo, perhaps ALAN could give some insite.

[cuttercollector]

Beside being audiophile turntables, which at least in the US means they are rare and cost thousands of dollars, the Garrard might not have enough torque to maintain proper cutting speed. The Lenco because of it's unique drive system would have even less torque.
I would think it would be better to either find a 50Hz. motor for the Rek-O-Kut or get a 220 to 110 transformer of adequate size to power the motor, then deal with the speed issue by having a new larger motor shaft collar machined that will compensate for the slower RPM of the motor on 50Hz.
This sort of thing was common for all sorts of turntables and tape recorders manufactured in the 50s and 60s. Regardless of where it was made there was another pully or shaft diameter to compensate for the frequency difference and some motors even had 2 switchable windings for the voltage issue. In fact Rek-O-Kut themselves probably made an export 50 Hz. motor adaptor back in the day. Any machinist with a lathe should be able to turn you this sleeve with a setscrew to hold it on the shaft.

[bancho]

Very simple and elegant solution is to buy a voltage/frequency controller... like Siemens Micromaster.
I have a presto lathe with presto motor and I use Micromaster 420... and it works perfect!
...by the way... I'm also from europe and I also get 220V/50Hz out of the socket.

[Simon]

Siemens Micromaster 420

they make a few versions - which one?

310055956551 on ebay


It may be better to get new drive made and cheaper

Brass knurled?

How would I work out the size?

20% extra?





I have done some testing with the Arm on a Technics 1210 MK2 - had a little problem with the quartz lock

So I did the simple hack out on the net.

http://technics.junglist.pl/hacking_technics.html

The is still some wow and flutter

I am told that the Numark TT series direct drive has a lot more torque the 1200= 1.5 TT =3.5

But I can not find a quartz lock hack for the TT

May have to get the one with the button to switch it off and on like the like the MK5 1210

[Simon]

Very simple and elegant solution is to buy a voltage/frequency controller... like Siemens Micromaster.
I have a presto lathe with presto motor and I use Micromaster 420... and it works perfect!
...by the way... I'm also from europe and I also get 220V/50Hz out of the socket.

I have looked at all the data sheets, I can not find a single phase to single phase output.

All I can find is a single phase to three phase output.

Any help would be great

[cuttercollector]

Regarding the size of the drive increase, I am no math whiz - if I was I would not be here. If you divide 50 into 60 (Hz.) you do get 1.2 which would be 20% percent bigger but I am not sure if that translates directly. It is a ratio problem. If you can figure out how many RPM the table is actually turning (put a marker like a slip of paper under a record on the table and count the RPM) on 50hz then you will know how many RPM it needs to increase. You know the motor shaft diameter and the internal drive surface of the table diameter, so you can figure out what the ratio needs to be to give the desired RPM. The Rek-O-Kut turntable is not 1:1 through the idlers as some tables are - except at 78 where both the motor and platter rubber tires are the same size - but you only care about the overall ratio of motor speed to platter speed being right.
I would try and emulate whatever is there for the drive surface. Knurled brass would work.

A word about drive systems in general.
They should operate at whatever speed the motor would free-run at locked to the frequency of line (or quartz locked on newer designs). That is to say they should have enough torque to not be pulled down by cutting.
Once a system is loaded down and operating at lower than it's optimum speed and you try and compensate by increasing voltage, frequency, servo pitch adjustment etc. you are in an area where it will never be reliable as RPM will vary with load as in depth of cut, where on the disc you are between the center and the edge etc. and won't be stable even as program material changes slowing on loud parts and having increased wow and flutter. To cut correctly everything must not slip in indirect drive systems and regardless, the motor has to have enough torque to stay at it's designed optimum operating speed under load.

[bancho]

maybe you should check the Siemens homepage... to see what they have.
On my controller there is written Micromaster 420. and it doesn't look so fancy like the eBay's one. But it is sweet though: you have different programs and you can make your motor spin with 33, 45, 78, (anything) rpm.
I thing siemens' engineers have enough expertise to help you - contact them!

[Simon]

ok if i go for the inverter - it has to be single phase to single phase...

They are quite rare second-hand

The new drive sounds a better idea


Hamilton sent me a picture of his mounted on a Numark deck

[Simon]

http://www.invertek.co.uk/product_optidrive_e1.aspx

http://www.acpd.co.uk/optidrive-e1-inverters.html

these guys make an inverter drive single phase

110-120V, 1 Phase input, 1 Phase output 50/60 hrz + speed controller - bit like a pitch control...

getting a price tomorrow - we will see.

[Simon]

Well £187 for the inverter


Got an idea...

CAR DC 12V--AC 110V 60Hz

with a 12v 30amp regulated power supply....


It will work a treat.

[blacknwhite]

Clever!

[Simon]

Got an idea...

CAR DC 12V--AC 110V 60Hz

with a 12v 30amp regulated power supply....


It will work a treat.

You will all be very glad to hear that it worked a treat....

[markrob]

Hi all,

I've done the same thing and it worked fine here. Keep in mind that the cheapy inverters are typically modified sine types, so your motor might run a bit hotter and you might hear some additional noise. Also note they are not typically quartz locked to 60hz, so the speed may be a bit off. Off the shelf mine read 62hz. I'm experimenting here with half speed cutting, so I reverse engineered my unit and modified it to allow me to adjust both freq and output voltage over a 2:1 range. This turns the inverter into a poor man's V/F drive. You have to set the two parematers manually, but this is no big deal. I use strobe disks I created for 33.33, 16.67, 45, and 22.5 RPM to set the speed and a DVM to reduce the voltage at lower speeds. If anybody is interested, PM me and I can email PDF's of the original schematic and my mods to make this happen. I'd bet most of these inverters use similar circuitry.