Battery Powered Vinyl Turntable Help

I recently purchased a Bush MTT1 vinyl turntable which I am trying to make portable so I can play records through a set of I-pod speakers on the move. I thought this was a good one to ‘mod’ as it has a built in preamp (one less thing to carry!). First of all I have swapped/removed the red/white output sockets and replaced them with a 3.5mm headphone jack so the speakers can easily be attached – this works great! The part I am stuck with is the turntable needs to be plugged in to the wall…and I want it to be battery powered. I have opened up the turntable and inside the wire from the wall goes straight into a transformer, then the transformer is wired to the turntable circuit with two blue wires. The transformer reads – 05/45 on the side, if that’s any use.

All I need to know is what voltage is being supplied to the turntable by the transformer so I can remove it and put batteries in its place, how can I do this?, can it be done?

Also wear the transformer connects to the circuit it says 'AC IN'. Can i just connect batteries?

Please see attached photos for anymore information, thanks!


 


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appolo6 years ago
Have a look at the motor and check for a label which may reveal it's operating voltage! Also with a DC multimeter you can check the motor voltage directly while it's running. Your pic shows + and - on the motors tag board. These motors are also speed stabilised with internal regulator circuits so may accept some voltage tolerances when selecting your cells. As already suggested feed your DC directly into the AC input point on the circuit board, but disconnect the leads from the transformer. Because the motor is regulated you may not need to worry about diode voltage loss.
lemonie6 years ago

While you're inside the case, why not fit a DPDT switch to the motor supply so that you can reverse the turntable...?

L
ledartist6 years ago
You _should_ be able to connect battery to the AC IN port of the PCB. I can see the full rectifier there, which means you can hook up the battery in either polarity. However, you need to know what voltage the transformer outputs. So you need a voltmeter or tester.
If you don't have one, and feeling bold, you can try maybe 6 V first, then if that doesn't turn the motor fast enough, go higher voltage.

Remember you are wasting about 0.8 V of battery power by going through the full rectifier.

superrob (author)  ledartist6 years ago
Thanks ledartist, just got out the multimeter, put it on the output points of the rectifier diodes and got a reading of just over 12v (12.48v or something) so i guess it needs 12v of batteries. i will connect the batteries after the rectifier as its easy to tell what is positive / negative and dont want to waste any volts. do you think 8 AAs would do the job? not sure how much amps / milliamps the turntable needs?
Sounds like you are on the right track. I don't think you get much play time with AA's but it's worth a try. My guess is C cell or something would be good though.
I have a small portable turntable that uses C cells. I think the motors are about the same.

superrob (author)  ledartist6 years ago
I think you are probably right, i want to able to use it for quite a while without having to change / buy loads of batteries. There might be space in the case for 8 C cells...almost. i just did a quick test by attaching a 12v DC adaptor i use to charge a radio controlled car to the points on the circuit after the rectifier, had it playing for about an hour and all is working fine, adaptors not getting really hot or anything, sound is loud and record is spinning at the correct speed.
Kiteman6 years ago
Have you checked the voltage and current being put out by the transformer?

You also need to see if it's being used as AC, or rectified to DC.