Issue with tone controls 9n a Japanese 70s stratocaster

musicalstash

Does this wiring look correct for a Japanese 70s stratocaster copy?  The volume and pickup selector work but the tone controls don't seem to be doing anything. 

It all looks stock and all the wires intact so not too sure what the issue is.

https://ibb.co/8NBBZmv

Thanks 

FelineGuitars

Have you tried both tone control in all 3 or 5 positions 

Obviously there won't be any tone control on the bridge pickup if it is 70s correct

musicalstash

FelineGuitars said:

Have you tried both tone control in all 3 or 5 positions 

Obviously there won't be any tone control on the bridge pickup if it is 70s correct

yes I've tried it on all controls but no affect on the sound. I'vealso tried putting the gain right up and using the tone control to see if it controls the "hiss " but nothing. Could it be a faulty capacitor? 

ICBM

musicalstash said:

Could it be a faulty capacitor? 

Possible but very unlikely - it's much more likely to be the switch. Try some contact cleaner on it. The wiring also looks correct and I can't see any cold solder joints. Try touching the tone pot terminals with the orange and pink wires with the switch in the middle and neck positions and the guitar plugged in - if you get buzz from those it's the cap, if you don't it's the switch.

The bad news if the switch needs replacing is that it's one of the 'short frame' type sometimes used on (especially Matsumoku) 70s MIJ guitars, so you can't drop in a standard modern switch. The way I would do it is to drill and tap a new switch for the shorter screw spacing, rather than butcher the pickguard (as usually done) by cutting a longer slot.

This is also an object lesson in providing a good clear photo of the possible problem area, by the way - it's very easy to see even things like the quality of soldering.

Funkfingers

ICBM said:

The bad news if the switch needs replacing is that it's one of the 'short frame' type sometimes used on (especially Matsumoku) 70s MIJ guitars, so you can't drop in a standard modern switch. The way I would do it is to drill and tap a new switch for the shorter screw spacing, rather than butcher the pickguard (as usually done) by cutting a longer slot.

The terminals on the seven-contact switch are (left to right) 1, 2, 3, common output, 1, 2, 3. 

The three pickups should go to one pole, the central terminal takes the signal to the volume pot, the second pole handles the tone control connections. Thus, it is possible for two pickups to share one pot.

I have the same switch from an Eighties Ibanez Roadstar II. 

ICBM

Funkfingers said:

The terminals on the seven-contact switch are (left to right) 1, 2, 3, common output, 1, 2, 3.

It's not one of those, it's the older version with two separate 3-pole switches, at the top and bottom of the switch - the green wire links the two rotors.

These switches are better quality and less prone to bad contacts than the later ones with the centre common terminal, but they can still get dirt in the contacts.

musicalstash

ICBM said:

musicalstash said:

Could it be a faulty capacitor? 

Possible but very unlikely - it's much more likely to be the switch. Try some contact cleaner on it. The wiring also looks correct and I can't see any cold solder joints. Try touching the tone pot terminals with the orange and pink wires with the switch in the middle and neck positions and the guitar plugged in - if you get buzz from those it's the cap, if you don't it's the switch.

The bad news if the switch needs replacing is that it's one of the 'short frame' type sometimes used on (especially Matsumoku) 70s MIJ guitars, so you can't drop in a standard modern switch. The way I would do it is to drill and tap a new switch for the shorter screw spacing, rather than butcher the pickguard (as usually done) by cutting a longer slot.

This is also an object lesson in providing a good clear photo of the possible problem area, by the way - it's very easy to see even things like the quality of soldering.

Tried the connectors and they did buzz when touched so connected a cap with the original one in place and it worked.

when I soldered it in properly removing the original both tone controls went off again.. Tried cleaning the switch with no joy.  Will leave it till have more time to sort.. 

ICBM

That means it's not the switch or the cap but something in the ground connection from the cap, most likely.

Ah... check the connection between the ground wire from the tone pots and the back of the volume pot. It looks like the wire is resting on top of the blob of solder instead of being wetted into the body of it. I didn't spot that at first, sorry!

musicalstash

ICBM said:

That means it's not the switch or the cap but something in the ground connection from the cap, most likely.

Ah... check the connection between the ground wire from the tone pots and the back of the volume pot. It looks like the wire is resting on top of the blob of solder instead of being wetted into the body of it. I didn't spot that at first, sorry!

You were right  , it was the earth wire on the back of the volume pot a bit of solder and it all came back to life .Thanks as always 

ICBM

It was one of those optical illusion things - when I looked at first it looked like a normal solder joint with the wire running into it, but when you described the continuing intermittent fault after changing the cap, I knew it had to be something in the ground connection, and it suddenly snapped into focus as a cold joint. Unfortunate that I didn’t see it before you changed the cap - hopefully the original one went back without too much trouble!

I have no idea how many times I’ve had to diagnose this sort of fault, and how easy it is to logically ‘identify’ the wrong cause at first, until after you’ve changed something you didn’t need to…