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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details. |
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25th May 2016, 3:39 pm | #1 |
Retired Dormant Member
Join Date: May 2016
Location: Rugby, Warwickshire, UK.
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Rockola Jukebox Power Supply Unit
Hi ... I've purchased a very dilapidated Rockola 481 Jukebox and have set about restoration. Completely missing was the power supply unit. I've secured a replacement PSU from the USA and need advice on configuring this to work at 240V. There is a jumper setting to alter but nothing else that I can see, but the 240V jumper setting is to one dead pin. Done this and applied power - nothing happens. Any advice or guidance welcome. Can post pics and more detail if anyone can help.
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25th May 2016, 4:27 pm | #2 |
Dekatron
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Location: Biggin Hill, London, UK.
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Re: Rockola Jukebox Power Supply Unit
If this is a switch-mode PSU, then it would be normal for the 240V (or 230V) setting of the jumper to be effectively open-circuit. In such PSUs the input circuit is a bridge rectifier feeding a pair of capactors in series, by adding a jumper from one side of the mains to the midpoint of the capacitors it becomes a voltage doubler. The former is for 240V mains, the latter for 120V mains, in either case the voltage across the capacitors ends up much the same.
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25th May 2016, 4:43 pm | #3 |
Octode
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Re: Rockola Jukebox Power Supply Unit
You may not be able to configure it directly to suit our mains. Quite a bit of American stuff only is only intended for their mains voltage despite there being an apparent tapping. The easy way is to get a 240 down to 115 transformer and connect it to its USA input.
Jim |
25th May 2016, 6:04 pm | #4 |
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Re: Rockola Jukebox Power Supply Unit
A circuit diagram of the PSU would help if you have one.
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25th May 2016, 7:39 pm | #5 |
Dekatron
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Re: Rockola Jukebox Power Supply Unit
It may be that although it seems you can change to 240 volt setting the transformer actually fitted could be only 110 volt. The pin to connect to may be fitted as a production convenience but not going to a transformer winding.
Have you checked the fuses and is there a transformer wire attached to the 240 volt pin. Circuit or photos may help us to help you. |
25th May 2016, 7:53 pm | #6 |
Heptode
Join Date: Nov 2008
Location: North Walsham, Norfolk, UK.
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Re: Rockola Jukebox Power Supply Unit
It's too early for a switch mode being a 80's machine. All the earlier 70's ones I have seen have a step down transformer nesting in the bottom of the unit. Even my CD3000 had a step down transformer and that was late 80's
Manuals here http://arcarc.xmission.com/PDF_Jukeb...ice_Manual.pdf although it doesn't show the PSU it does show 120 & 240 volt connections on the internal wiring diagram maybe the supply you have is a US only one |
25th May 2016, 8:07 pm | #7 |
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Join Date: May 2016
Location: Rugby, Warwickshire, UK.
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Re: Rockola Jukebox Power Supply Unit
This photo shows what is printed on the transformer. Pin 6 is not connected to anything. On the front of the PSU there is also a list of countries/voltages with a "dot" used to mark one of the list (currently marked USA/110v), which implies some sort of adaptability.
I understand this machine was manufactured in 1981 but was based on a 1979 model. I'm away from the machine this evening but will try and post more pics later. |
26th May 2016, 10:10 am | #8 |
Retired Dormant Member
Join Date: May 2016
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Re: Rockola Jukebox Power Supply Unit
OK... thanks for the advice so far. From what I can make out the transformer is one with a multi-tapped primary and there is a jumper and some spade connectors which can be swapped around in various combinations. If I want to test and then run at 240v then I'm happy to rewire the box permanently to the full winding. I can probably untangle this with a lot of thought and a multimeter but if anyone here can give me a pointer as to which colour cables are likely to be the 240v option that would be great. There are 6 cables from the primary as per the attached photo. The voltages referred to on the panel are 100, 120, 220, and 240, in various countries too - US, Canada, Japan, UK, Germany and Belgium. Presumably the transformer is able to cope then with 50Hz as well as 60Hz then (I know they can get too hot if run at full voltage 50Hz if only designed for 60Hz.)
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26th May 2016, 3:39 pm | #9 |
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Re: Rockola Jukebox Power Supply Unit
I'll hazard a GUESS that the live wire of the incoming mains supply is wired to pins 3 and 6.
Then: Pin 1 =100V Pin 2 = 120V Pin 4 = 220V Pin 5 = 240V There must also be a 0V somewhere, presumably connected directly to the neutral wire. Some resistance checks might prove this or otherwise.
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26th May 2016, 5:22 pm | #10 |
Dekatron
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Re: Rockola Jukebox Power Supply Unit
This does sound like it's a transformer with one multi-tapped primary. On the other hand it is a bad idea to guess!
I would start by finding out where those 5 wires end up. It is likely that 4 of them end up on the voltage selector socket and the other goes to one side of the mains (maybe via a fuse or main switch). But check, And if 4 do go to the votlage selector socket (I would guess to pins 1, 2, 4, 5), then I would expect another wire on that socket (pin 3?) going to the other side of mains. If that agrees with the machine, then the next thing to do is to disonnect the secondary winding(s) if at all possible (unplug relevant connectors etc) set it to 110V as supplied, and connect the transformer to a 110V AC supply, from variac or step-down transfomer. It won't take much current. Now with an AC voltmeter, connect one side to the side of the AC input that goes to the transformer wire _not_ connected to the voltage selector and measure the voltage on the 4 wires on the selector. If these are the expected voltages that Station X suggests, then you know what the taps on the primary are (the primary winding will act as an autotransformer when run like this, of course, producing the other voltages). But as I keep saying, check things. Make sure you know how it is currently wired before you change anything. |
26th May 2016, 5:42 pm | #11 |
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Re: Rockola Jukebox Power Supply Unit
Where is the actual voltage selection plug? I assume it plugs into a socket connected to the other end of the wires? If so can you post a picture of the connections to the socket.
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26th May 2016, 7:18 pm | #12 |
Dekatron
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Re: Rockola Jukebox Power Supply Unit
I've just looked at a 240 volt power supply (not sure it's the same model as I can't find any numbers) and it has terminals where the mains lead connects and is clearly marked L N E (although not necessarily in that order) and printed 240 volts. It also has the same drawing attached to the transformer as your picture. I have a circuit for an earlier box (453) which shows two different power supply circuits on the same sheet. One marked 'domestic' which is 110 volt and an 'export' version where it's 220/240 volts. The lighting chokes are different on each, being 110 or 220 volts. There are 2 transformers shown. One only has windings for 100, 110 & 120 volts and seems to feed the main workings. The other shows extra windings to 220 & 240 volts and shows the secondary as 45-0 45 and goes to external tags which may be to the amplifier.
On the 110 volt version the 220/240 windings of this transformer are not connected. Don't know if this helps or just adds to the confusion. |