Uniselector wanted

[garythegolfer]

Hi,
Did you have any luck getting hold of a Siemens uniselector? It turns out that I could really do with one of these as well.....for the same reason! I have finally found the real reason that my Electrodart was scrapped.

Yours hopefully,
G

[slotalot]

Hi Gary, not got the right one yet
surprised to hear of Siemens uniselectors being used in an Electrodart have you got a photo of your machine? what problems do you have with it??
Regards Stuart.

[garythegolfer]

Stuart,

Earlier photo attached showing the 2 (black-faced) Siemens uniselectors. This was part-way through the rewiring. The machine had been cannibalised and had much of the wiring missing/damaged. I used your wiring diagram to try to work out how it should have been wired (Thank you!). I have uploaded my revised diagrams (based on your work) to the resources section. There are some minor revisions still to come. The rewiring is just about complete now and the machine does sort of work. The biggest problem now turns out to be the Left hand uniselector......the machine runs and pays out sometimes. Mostly it pays out double or doesn't payout or pays out continuously. All the faults are a function of the faulty left hand uniselector.

The left hand uniselector has damaged wipers tips. They had been butchered and are of uneven lengths so that is currently impossible to get all the wipers to simultaneously sit somewhere near the middle of the bank contacts.

I do have a very nice 6-way (GEC?) uniselector but that needs about 50 volts and the Siemens variety (and my whole electrodart) function on 24 volts. Making the LH uniselector (alone) work from 50 volts turns out to be a real pain.

The easiest solution for me would be to replace the LH Siemens.....preferably whilst retaining the existing uniselector bank and wiring.

Gary

[slotalot]

Hi Gary, that range of jamieson machines can be tricky buggers to set up at the best of times, I wish you luck, I am sure you will get it sorted given time, if I do manage to find any siemens uniselectors I will let you know, it is only the lower half / rotor of the selector that I need, looks like someone has had this apart and lost the lower section
I am sure one will turn up

[garythegolfer]

OK. There's good news and bad news. I finally bit the bullet and rewound the 50v GEC 8 way uniselector to work from my Electrodart 24 volt system. It turns out that (for me at least) 2070 turns of 0.22mm wire can be replaced with 1040 turns of 0.31mm wire. This steps 50v down to 24v whilst keeping the power about the same (~30 watts). ie the same magnetic pulling power This was all the 0.31mm wire that would fit on the bobbin.
[Incidently an excellent primer on rewinding can be found here: http://www.qsl.net/ki7cx/Coilrewind.htm and an excellent calculator, if you want to be more technical, can be found here: http://www.daycounter.com/Calculators/C ... ator.phtml ]

That was the good news. The bad news is that I now have to unsolder all the left hand (Siemens) uniselector connections and reconnect them all to the replacement GEC uniselector......

[badpenny]

Here's to you Gary
Woo Hoo for the good news.

Good luck regarding the bad news.

[pennymachines]

I'm still trying to track down a SIEMENS 25 x 4 UNISELECTOR No 15A, 1950s Yes, Slotalot was trying to source one for my Dial For Money. Unfortunately, he's otherwise engaged of late and no longer has time to fix machines. so I'm going to have to get my fingers dirty (or more likely burned ) on this one. But first I have to find that uniselector...

[badpenny]

This is currently on ebay at the moment eBay Click
GEC and Siemens are related, I can't comment on suitability especially regarding model numbers. The vendor appears to be savvy about electronicalness so maybe could advise you.

BP

[garythegolfer]

I believe the Siemens uniselectors were nominally about 24 volt whilst the GEC uniselectors were nominally about 50 volt. So they are not really interchangeable except if you take the original coil windings off and replace them with the right number of turns of the correct and different diameter coil wire. This is what I have done in desperation a couple of posts above.

Regards
G

[badpenny]

Good point, of course we don't know the voltage Mr P's machine is feeding on nor if there is a resistor in line.

Edited to point out to myself that even if there were one it wouldn't control voltage - fool.

[treefrog]

Dumb question, but if the voltages so the main issue is it not easier to change the voltage supply?

I did pick a few uniselectors recently , with 5 lines, but no idea of brand, as there are no labels, one is brand new old stock

[garythegolfer]

I did consider using a 50v Power supply. You could get a laptop-type 50 volt PSU from EBay for about £10 and use BOTH 24 and 50 volt power supplies and "steering diodes". Alternatively, you could try to use ONLY a replacement 50v PSU. I did consider this but it also seemed quite an inelegant solution that scraps the original transformer/rectifier. I was willing to play with a low voltage uniselector coil but less willing to chance my hand with rewinding a mains transformer.

Given the choice of a) 50v machine conversion, b) mixed 24/50v operation and c) conversion of the (new) uniselector from 50v to 24v, I chose the latter. It is of course a personal choice but for me the coil rewind was the least worst option. Originally I was considering how to keep the machine more "authentic".....but couldn't find a replacement 24v (Siemens) uniselector. It would perhaps have been better to change BOTH uniselectors to GEC version since my mods will make my machine an odd hybrid. I suppose it depends what the objectives are. If you want to sell at a maximum price, authentic (or the appearance of authentic) has much value. I have had this scrapped machine for about 50 years and my objective has become simply to make it work! (My rewiring solution is also quite unorthodox.....so I really have already given up on "authentic".)

I can't claim my solution is "right": it just suits me. I started from a scrapped and cannibalised machine. There may well be better solutions..... Who knows, if I ever get this working, I may consider replacing the other Siemens uniselector with a GEC 50v version (and rewinding its coil).....at least I know how to do it and have the coil wire to do it!

It's amazing how defensive I have become for even a sub-optimal solution.....!

I suppose my main intention was just to show that rewinding the uniselector coil was a possible/practical solution. And give enough technical help for anyone else who wanted to try it.

Oh and by the way....it was never a dumb question.

Regards,
G

[pennymachines]

Your approach sounds good to me and may have saved me figuring it all out for myself.

I may consider replacing the other Siemens uniselector with a GEC 50v version

If you do, you'll know who to sell the Siemens uniselector to...

[treefrog]

No idea what type this is, but is brand new.

[operator bell]

Tip 'o the hat to Gary The Golfer for rewinding the coil. I was going to suggest it before I saw that you'd done it. I've done it myself. I once bought a job lot of uniselectors on Ebay and when they showed up they turned out to be SIX VOLTS. I had no idea that six volt uniselectors even existed. The coil resistance was about 10 ohms. I rewound them for 24V.

I encourage anyone needing a different voltage coil to have a go at rewinding. It's tedious to do it by hand, and it needs to be neat, but it's not difficult. For half the voltage, you need wire that's twice the cross sectional area, which you can find out from a copper wire table. Being twice the area means you can only get half the number of turns on compared to the original, so the final resistance will be a quarter of the original (half the length times half the ohms per foot). Then at half the original voltage, you get twice the original current. The magnetic strength of a solenoid is given by ampere-turns, so now you have twice the current times half the turns, or the same number of ampere-turns (and thus the same magnetic strength) as the original.