Hohner B2a

[Rayman]

I picked this very sorry B2a up. Filthy dirty, really horrible it was (it’s clean now).

 

It’s missing its jack assembly. I assume that a telecaster style jack plate will work, but the suggested barrel jack absolutely does not fit in there. So I ordered a regular style stereo jack, which I hope will work.

 

Question is, I have two loose wires, blue and white. I assume that there should be 3 for a stereo jack? Anyone have one of these that can be bothered to open it up and take a couple of pics for me?

 

 

 

👍🏻

Edited July 12 by Rayman

[Rayman]

There’s also a loose red wire in here…. which I assume goes against the live contact where the circuit board slots in? It is definitely meant to be loose, it hasn’t come off anything. It only popped up when I pulled out the circuit board/trim pot insert to clean it 

 

[Reggaebass]

Hi Rayman, mine is next to me, give me a few minutes and I’ll look 

[Reggaebass]

Any help 

[Rayman]

Thanks for that. Different layout unfortunately, but thanks anyway 👍🏻

[Reggaebass]

1 minute ago, Rayman said:

Thanks for that. Different layout unfortunately, but thanks anyway 👍🏻

I don’t know anything about electrical stuff but yeah looks different, good luck 

[tauzero]

My B2AV has (or had, before I replaced the dead preamp) the same layout as Reggaebass's. Doing a search, @casapete and @simon1964 both had XLR output B2As in 2013, one or both might still have them.

[casapete]

51 minutes ago, tauzero said:

My B2AV has (or had, before I replaced the dead preamp) the same layout as Reggaebass's. Doing a search, @casapete and @simon1964 both had XLR output B2As in 2013, one or both might still have them.

Unfortunately my B2A is long gone, sorry!

[Rayman]

Yeah there’s surprisingly little on the net to help…. I’m sure I’ll figure it out.

 

 Thanks anyway 👍🏻

[Hellzero]

Check here for the wiring of the preamp inside the battery compartment: https://my.hohner.de/t/hohner-b2a-spare-parts/1060

 

And here some photos of the XLR preamp wiring:

 

 

Edited July 12 by Hellzero

[SpondonBassed]

Mine...

 

 

 

 

 

I hope this helps.

 

It looks like the shielding on your white core wire needs to be exposed a bit more.  That'll be your third wire.

 

@Andyjr1515 replaced the jack socket for me some time back.  I didn't want to put a strain on the preamp harness and end up like you seem to have but the order of the wire colours is just visible.

 

 

 

 

 

 

 

 

Edited July 12 by SpondonBassed

[Hellzero]

And here is the preamp diagram/wiring:

 

[Rayman]

Awesome, thanks so much 

[SpondonBassed]

3 hours ago, Rayman said:

Awesome, thanks so much 

 

You're welcome.  Glad to be of help.

[simon1964]

On 12/07/2025 at 12:19, tauzero said:

My B2AV has (or had, before I replaced the dead preamp) the same layout as Reggaebass's. Doing a search, @casapete and @simon1964 both had XLR output B2As in 2013, one or both might still have them.

One of my sons "borrowed" my B2A some years ago, so I don't have access to it just now (it does have the XLR output). Hopefully the wiring diagram further up the thread helps - if not, let me know and I will ask him to send me a photo of the wiring.

Edited Thursday at 09:35 by simon1964

[Rayman]

A couple of questions…. Because I’m not having much joy here. Is this stereo jack wired correctly?

 

 

[Rayman]

And the preamp wiring… the red wire that was loose (next to the white) looks like it should go to there, so I attached it… does that look right?

 

 

 

[Rayman]

I fear this thing could be jiggered, but I’m not giving up yet.

[SpondonBassed]

2 hours ago, Rayman said:

I fear this thing could be jiggered, but I’m not giving up yet.

 

The jack socket looks okay from what I can see.  I can't comment on the preamp.  I was unable to get enough slack in the loom to pull it out that far.

 

Have you tried with a battery yet?  You have to have a jack plugged in and the switch to the correct position for the preamp to work.

[Rayman]

Yeah, I’ve bypassed the battery box, and connected a clip on battery terminal, and yep, lead plugged in etc, and no joy at all. 

[SpondonBassed]

24 minutes ago, Rayman said:

Yeah, I’ve bypassed the battery box, and connected a clip on battery terminal, and yep, lead plugged in etc, and no joy at all. 

 

I can't suggest anything else, sorry.  Try Repairs and Technical.

[Hellzero]

Why didn't you check the link I provided above with everything explained about the wiring of the preamp, because the red wire doesn't go there...

 

It's fully documented with pictures and you also have the wiring diagram.

 

Go and have a check, you are close to it.

[Rayman]

13 minutes ago, Hellzero said:

Why didn't you check the link I provided above with everything explained about the wiring of the preamp, because the red wire doesn't go there...

 

It's fully documented with pictures and you also have the wiring diagram.

 

Go and have a check, you are close to it.

Yep, I did, and I have had the red wire connect into the corner, as per the photos, but that didn’t work either.

[Rayman]

That’s where I’m up to, unless I’m missing something that should be right 
 

37 minutes ago, Hellzero said:

Why didn't you check the link I provided above with everything explained about the wiring of the preamp, because the red wire doesn't go there...

 

It's fully documented with pictures and you also have the wiring diagram.

 

Go and have a check, you are close to it

[Rayman]

With the jack lead plugged into the bass and connected to the amp (turned off), the red LED light now comes on. Turn the amp on, and the red light goes off again. Turn the amp off again snd the red LED comes back on….. 🤦🏻‍♂️. There’s something in the wrong place, I just can’t figure it out. I think someone who knows more about active electronics than me needs to have a look.

 

I can wire passive looms all day long, but this active stuff is doing my nut in.