Members thomas998 Posted April 21, 2015 Members Share Posted April 21, 2015 I just picked up an old Hohner B2A F1 to play around with… unfortunately it looks like a previous owner decided to play electrician and has done a bit of who knows what inside it. At the moment I get sound when I plug it in, I popped a new battery in and the active electronics seem to work as I get a nice boost when I flip the switch… But I know there are things still missing or broken. It has 3 knobs, I think they are two volumes and one tone but only the volume control toward the neck does anything the other knobs do absolutely nothing… I expect I will have to remove everything and rewire from scratch, but before I do that I have one glaring problem. The wiring diagram I found online that is supposed to be for a Hohner b2a is for a bass with 3 controls, 2 pickups and 1 output connection… The B2A that I have has 3 controls, 2 pickups 1 output connection and a hole where apparently another connection was supposed to be… I have no idea if it was a standard guitar jack or a XLR or what… I suspect it was for something as I can see some loose wires inside that I assume connected to whatever it was… I even have 2 screw holes near the larger hole that would appear to have been for holding whatever was supposed to be there in place. Does anyone have a B2A with this type of layout and if so what type of jack am I missing? And more importantly am I right to assume the control layout is supposed to be 2 volumes and 1 tone or is that incorrect? Trying to put this thing in working order but frankly at the moment I’m not sure what working order should be. Link to comment Share on other sites More sharing options...
Members lug Posted April 22, 2015 Members Share Posted April 22, 2015 Found this, don't know if it helps or not. http://i276.photobucket.com/albums/k...SCircuitBd.jpg and http://i276.photobucket.com/albums/kk29/seanfunk/BBassWiringDiagram.jpg Link to comment Share on other sites More sharing options...
Members thomas998 Posted April 22, 2015 Author Members Share Posted April 22, 2015 Thanks for the links. Those match up with the information I had already been able to find. Unfortunately I have no idea how the mystery plug was wired in. I did find a photo of a B2A that had both a standard guitar jack and an XLR jack right where the one on the guitar I have is located, so I know now what goes in the mystery hole, just not sure how to wire it in... and unfortunately I've now determined that the Mr. Wizard that tried to work on the guitar last didn't even use the correct parts... For anyone trying to rework one of these I have now found from a parts list that they have 2 volumes and 1 concentric tone control... volumes should be B100K the concentric tone should be dual 100k... Link to comment Share on other sites More sharing options...
Members WRGKMC Posted April 23, 2015 Members Share Posted April 23, 2015 The jack is a stereo TRS jack. The tip is the guitar signal, the ring is the battery and the sleeve is the ground. When you plug in a regular 1/4" guitar jack, the ring and sleeve make contact and applies the negative power supply of the battery to power up the circuit. When the cord is removed, the battery is disconnected so you don't drain the battery. Link to comment Share on other sites More sharing options...
Members thomas998 Posted April 27, 2015 Author Members Share Posted April 27, 2015 Okay... I had time to remove all the electronics this weekend and I'm pretty baffled at the active controls now. The sheet lug attached along matched the one I had previously found on a B2A... but the electronics in the guitar are different. The schematic show 11 wires coming off the active module.... The module in the actual guitar only has 5 wires coming off it with one going ot the battery so only 4 that could connect to the other bits and pieces. Anyone ever seen a Hohner active bass circuit with only 5 wires on it? If so any info on what those wires should go to would be appreciated. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted April 29, 2015 Members Share Posted April 29, 2015 Take some pictures. If I can see it I may be able to help. When an instrument is old and pre dates the internet its pot luck finding the correct diagram. I can usually figure out the ins and out for it so long as you didn't have other armatures screwing around in there. Link to comment Share on other sites More sharing options...
Members thomas998 Posted May 6, 2015 Author Members Share Posted May 6, 2015 I finally managed to find someone from Hohner's German office that was able to provide me a schematic of the B2A FL.... I would upload the photos but they are apparently too large to upload. If anyone ever needs them to work on one of these basses let me know and I'll email them to you. The confusion appears to come from the fact that they used a different setup in the fretless bass than they did in the fretted. The files that are linked in the second post to this thread are for a fretted bass... fretless will be different. Link to comment Share on other sites More sharing options...
Members Maret Guiatsr Posted December 25, 2015 Members Share Posted December 25, 2015 Hello folks, Can any one provide me a picture of the output jack plate on a Hohner B2A F1, I have included pictures of the bass I have. It's missing the output jack/plate and I would love to see what one looks like. I can not find a picture on the internet. Which is odd. Thanks a bunch in advance. Also if anyone knows where I can find the missing parts to repair this bass that would be absolutely incredible awesome! I have sent an email to Hohner in Germany, but I figured I would ask the experts here on the forum as well. Take care everyone and thank you again Sincerely James Link to comment Share on other sites More sharing options...
Members Julie A Posted January 22, 2021 Members Share Posted January 22, 2021 The extra hole you have was an XLR from the factory. Not all B2A series Hohner basses had them. My first one did but my current one doesn’t. Julie Link to comment Share on other sites More sharing options...
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