Grambo Posted February 5, 2010 Share Posted February 5, 2010 I just bought a pre-owned Hohner "Jack" and really quite like it - but I think someone has had their sticky fingers in the electronics 'cos I can't work out what the controls do. The major problem is that it is not possible to turn the output off using the knobs - I figure that the co-axial control is for the active tone circuit (which doesn't interest me) with the two single pots controlling.......what? - they both do something but seem to alter tone, not volume. Anyone out there got one of these, and can explain what it [i]should[/i] be doing? Cheers! Quote Link to comment Share on other sites More sharing options...
kets Posted February 7, 2010 Share Posted February 7, 2010 The two single knobs should be volume controls for the two pickups, just like on a jazz bass. The other one as you have guessed is the boost for the active circuit. Bass on the outside and treble on the inside. There should also be a small toggle switch making the bass active or passive. Sounds like someone has been buggering about with it. The question is why? Quote Link to comment Share on other sites More sharing options...
Grambo Posted February 7, 2010 Author Share Posted February 7, 2010 Thanks - that's what i figured. It would seem that it has indeed been buggered about with! Anyone got a circuit diagram for these things? - if not I might just re-wire the pups from scratch.... Quote Link to comment Share on other sites More sharing options...
Grambo Posted February 14, 2010 Author Share Posted February 14, 2010 [quote name='Grambo' post='737866' date='Feb 7 2010, 09:26 AM']Thanks - that's what i figured. It would seem that it has indeed been buggered about with! Anyone got a circuit diagram for these things? - if not I might just re-wire the pups from scratch....[/quote] OK - update time.... I have re-wired the pups using a simple JB type circuit, and guess what? - it's exactly the same The guitar is fitted with EMG select pickups which are, I think, the originals. They obviously don't require power, as they sound good passively and have only hot & ground connections. I am still unable to turn the output off using the volume pots - the bass is fitted with standard pots (I think they are 500k) Could it be that these pups require a different impedance control circuit? I have trawled the EMG site but found nothing really helpful. I'm sure one of you guys out there has the answer! Quote Link to comment Share on other sites More sharing options...
kets Posted February 14, 2010 Share Posted February 14, 2010 If you give me a day or two, I could take a few photos of the inside of the cavity on mine or make a note of how it's wired. The EMG select pickups are standard and don't need power. Only the tone controls are active (If you have it in active mode). If you run it in passive mode it doesn't need a battery in it, which is the way I use mine all the time! Quote Link to comment Share on other sites More sharing options...
BIG.J Posted February 14, 2010 Share Posted February 14, 2010 I have had a few of the Jacks, I have a Hohner B Bass at the moment. It uses the same Guts but with EMG Select Jazz Pickups. My bridge pickup volume pot tracking has gone, I have no control over it. Not sure if its the same sort of problem you have but i need to replace mine ASAP. Cheers & good luck Justin. Quote Link to comment Share on other sites More sharing options...
BIG.J Posted February 14, 2010 Share Posted February 14, 2010 Ahh! Just one more thing. I have had a faulty battery compartment on these too, I had to lift one of the corners of the battery slightly do get a good connection, Not realy stripped it to see if there were any dr joints etc. Just a quick fix for now. Quote Link to comment Share on other sites More sharing options...
Grambo Posted February 14, 2010 Author Share Posted February 14, 2010 [quote name='kets' post='745223' date='Feb 14 2010, 08:17 PM']If you give me a day or two, I could take a few photos of the inside of the cavity on mine or make a note of how it's wired. The EMG select pickups are standard and don't need power. Only the tone controls are active (If you have it in active mode). If you run it in passive mode it doesn't need a battery in it, which is the way I use mine all the time![/quote] Thanks for the input! My bass is now completely different to standard as I have disconnected all the active components, and wired each pup via its own volume pot direct to the jack socket. I don't understand why I can't reduce the volume using said pots - there must be some sort of impedance issue, I just can't find out what.... Quote Link to comment Share on other sites More sharing options...
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