Tone pot gone awol or something else ?

[fleabag]

Its twin soapbar single coil pickups,  tone pot for each pup, +  single blend + single volume, + active / passive mini switch.  

Neck pickup is fine, tone working, but the bridge pickup tone is bizarre.   When the tone is full up,  volume on full , it should be very toppy, but its the opposite.  Volume is fine. When rolling off the tone, almost all volume disappears and tone is extremely thin and trebly.  The loss of volume is huge, though still audible. 

Hard to diagnose for anyone i'm sure,  but is this the tone pot's fault, or bridge pup going down ?

[BassBunny]

What bass/electronics are we talking about here? 

Pics if the control cavity would help as I'm struggling to come up with a pre-amp with that configuration.

[Dan Dare]

in active or passive mode?

Edited November 9, 2020 by Dan Dare

[fleabag]

Its a Status Matrix,  and there's a  PCB involved. 

Its only a dodgy tone pot in active, because in passive, both tone pots are out of the circuit

Edited November 9, 2020 by fleabag

[fleabag]

If this is any help,  i got the schematic from Status for this TB42 circuit.  The blend pot has to be added seperately but has the schematic

 

[fleabag]

I think i may be confused.  It seems from the scheme that they're not seperate tone pots for each pup, but  a bass pot and a treble pot.

None the less,  when turning up the treble pot  ( the dodgy one )  i dont get any treble, though volume is fine.  Its when backing off that almost all volume disappears, and it goes really thin, trebly, no bottom at all

[Woodinblack]

I was going to say, are they not bass and treble? It wold be odd having a tone for each pickup

[BassBunny]

8 minutes ago, Woodinblack said:

I was going to say, are they not bass and treble? It wold be odd having a tone for each pickup

Unless it's an ACG or WAL that are filter pre-amps with a stack per pickup. 

Bass and treble makes much more sense.

[fleabag]

Thanks guys

Does that make a difference to the problem ?

[Woodinblack]

I would say that it sounds like the top connection of the bass pot has broken off or has a bad connection.

If this is the circuit, which google says it is, if there is something missing around R8, top of Vr1, you would probably get something like that

[fleabag]

Bit over my head woody, but  is R8 a resistor  ?  I  will have to remove the preamp,  because its impossible to see the wires ( or resistor ) on the bass pot, as you can see from the photo

Edited November 9, 2020 by fleabag

[Woodinblack]

7 minutes ago, fleabag said:

Bit over my head woody, but  is R8 a resistor  ?  I  will have to remove the preamp,  because its impossible to see the wires ( or resistor ) on the bass pot, as you can see from the photo

Sorry, I meant R6 (in the diagram - above the pot that says 'bass'). But it may not be that, just that if there was a break at some point around that resistor, it could lose all bass when turned down. So the bass control is the bottom one on the outside, so on your circuit board picture it is the one on the top left. 

So around here:

Check nothing is obviously broken or badly soldered or something.

[fleabag]

Thanks mate, but its the treble pot thats facked, not the bass pot, but yes, as you look at the photo above, its the pot top left.

I'll have a week look at the area you have marked.  Ta 

 

[Woodinblack]

5 minutes ago, fleabag said:

Thanks mate, but its the treble pot thats facked, not the bass pot, but yes, as you look at the photo above, its the pot top left.

You said it is the one that you originally called the 'bridge tone', which is the one nearest the socket in your image? I would see that as the bass pot, the treble pot appears to be doing what it should isn't it?

[fleabag]

You could be right. I may have them mixed up 

Yes its the one nearest the jack socket.

[fleabag]

Well,  i took the PCB out with 3 pots attached, then the blend.  Managed to knock a wire off in the process,  but soldered it back ok.

Whatever has happened, i dont know, but its back working.   I dont get it, but hey ,  gotta be happy with it 

Thanks for all the help  Woody and chappies

[Baloney Balderdash]

18 hours ago, fleabag said:

Well,  i took the PCB out with 3 pots attached, then the blend.  Managed to knock a wire off in the process,  but soldered it back ok.

Whatever has happened, i dont know, but its back working.   I dont get it, but hey ,  gotta be happy with it 

Thanks for all the help  Woody and chappies

Sounds to me like the wire that was torn loose when you took out the PCB already had a weak connection/bad solder point to begin with, which is why it fell off, and which is why your problem was fixed when you soldered it back on properly.

In fact that would make absolutely perfect sense to me, and answer you original question as to what caused the issue you described in the first place.

 

 

Edited November 10, 2020 by Baloney Balderdash

[fleabag]

Quite right  BB