Juno 6 Tuning

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slowalan
Posts: 1
Joined: 13:21, 15 May 2006

Juno 6 Tuning

Post by slowalan »

Just got a Juno 6..great little machine.

But tuning is just over a full tone flat and cannot be fixed with the small knob on the back.

I can get it into tune by using the transpose button, but then I can't use this button for snazzy modulations.

Does anyone know if the Juno 6 has tunable pots inside, and if so, how to do it?

Regards

Slowalan
batpuppy
Posts: 5
Joined: 23:04, 26 January 2014

Re: Juno 6 Tuning

Post by batpuppy »

Hi,

Look, don't shoot me for posting 8 years after this was posted. However, I wanted to put this out to all Juno 6 users who have this issue (especially if, like me, your Juno 6 spent the last 10 years in the loft/attic before a bit of nostalgia set in).

If your Juno 6 is well off tune like the previous poster then you can do something about it.

Firstly, the legal disclaimer. if you are not technically minded then you really should take this to a professional. You would be working on a live circuit board!!! The board to the far left of the base with the big capacitor and lots of fuses will kill you if you touch it. Likewise, the chips on the main board (the big one to the middle and right of the base) will fry if you have any static in you and you touch the board, un-isolated in which case that will likely be the end of the Juno.

If you wish to proceed...

If you have a PC with soundcard and software tuner, or guitar tuner, or even a frequency monitoring multimeter (Hz), you will need to connect it with a cable with a jack inserted into the mono output on the back of the Juno 6 leading to input of the device you choose. You may have to make up a cable for some devices. Have your tuner or multimeter set up like this and running before you switch on the Juno 6.

You also need a super small (tiny) flat-bladed screwdriver with insulated handle - make sure it is rated for electrical insulation.

Procedure

Set your tuning control on the rear panel to dead centre.

Ensure that the 'Octave Transpose' button is in the middle ('Normal') setting.

Ensure that the 'Arpeggio Mode' toggle switch is in the 'Up' position

In the wood effect ends there are two Phillips Head screws per end. Unscrew these and take them out. With the main lid closed (the one with all the sliders on), you will need to hold down the 'Key Transpose' button WHILST powering on the Juno 6. You are now in service mode and all the oscillators sing simultaneously.

High voltage alert. Now, you need to lift up the main lid and carefully push it back on its hinges without touching anything else so you can see the main board clearly.

About 2/3 of the way towards the right of the main board, nearer to the keys, there is a cubic-ish metal-encased component on the board, standing proud, which if you look closely, is called 'L1'. The writing is hidden to the back of the component, on the board, as you face the keys. If you have the correct one then it has a tiny, grey, flat screwdriver slot on the top. With an eye on your tuner or frequency meter plugged into the Juno 6 mono out, with one hand, press and hold synth key A4 (below the VCF LFO slider) down and with the other plus screwdriver, gently tweak the position of the grey slot until it either...

. Gives you a reading of 'A4' pitch on your tuner or if you have a fancy multimeter...
. Gives you a reading of 440Hz

Now, due to age of materials, as soon as you lift off the screwdriver from the slot, it will rebound a little. you need to compensate with a little 'trial and error' until you reach a stable 440 Hz or solid 'A' with the screwdriver off.

Once you have this stable with screwdriver away from the component, close the lid and power off. Screw the end screws back in through the end panels.

Power back on and check the tuning on the 'A4'. With a little tweak of the tuning adjustment pot at the back panel, you should be back in business.

If this doesn't work then you need a replacement of this component, in which case, if you are not an electronics engineer, you need to get it serviced.

Cheers,

batpuppy
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