JM wiring problem - i've bodged something

[johnnyseven]

You may remember an old thread of mine where I asked for suggestions on how to make my JM less trebly. To fix this I put a 250K volume pot in my JM and changed the tone pot back to the original (1 meg?). I was pretty sure I soldered everything in the same place as before however I must have bodged something up as now the rhythm circuit doesn't work, it just goes silent when engaged - no biggie though as I don't use it much. Also when I touch the tone knob it seems like there is a loose connection somewhere as the sound goes from sounding like it should, relating to where the tone control is set, to sounding like the knob is always on 10 - when sounding like this turning the pot does nothing. Can anyone suggest what the issue is?

[Johno]

Treble check schematic & try starting over incase of dodgy solder joint.

I had untold probs just swapping out a my Jap pups for Duncans (Which I no longer like)a few months back..... the schematic I got off Duncan was wired different to my guitar. I should have left in the old wire & just soldered the pups on... you live & learn/take to a tech.

[Doog]

Both problems could well just be cold solder joints, although it's possible some stray solder got inside the tone pot or summat.

Do you own a digital multimeter?

[johnnyseven]

I didn't check a schematic, I figured if I just soldered where the old wires were it would work ok. Maybe it's just an issue with my dodgy soldering, as i've said before my electronics knowledge and soldering are basic at best. I also don't own a multimeter and wouldn't know how to use one if I did. Next time I change the strings i'll take it apart and check over, if I can't sort I know a tech guy who'll probably be able to sort for £20 or so.

I had untold probs just swapping out a my Jap pups for Duncans (Which I no longer like)a few months back..... the schematic I got off Duncan was wired different to my guitar. I should have left in the old wire & just soldered the pups on... you live & learn/take to a tech.

I've seen a few Duncan JM schematics which seemed to me to be different to what is actually in my guitar. One time I soldered the pickups in and the pickup selector worked the opposite way round to normal, I managed to work out how to fix it though.

What SD JM pickups did you fit? I've had most of them in the past but the only ones I like are the Antiquity II's which I currently have and the Quarter Pounders, i'd be interested to try the Antiquity's though.

[Johno]

I have an SJM2 neck & a Quarter pounder SJM3 in the bridge.

[johnnyseven]

I tried the Hot ones, didn't like them - too dull sounding. I liked the Quarter Pounders when I had them but much prefer the Antiquity II's, lovely clean sounds and sound awesome distorted too - I bit pricier though.

[Johno]

Yeah I want to try the Antiquity II's don't see them much in the UK, might give the AVRI's a spin first as they are the cheaper & more available option.
The pickups I have sound great for heavy stuff but I'm on a clean & reverb trip at the moment.

[johnnyseven]

I got mine sent over from the US back when the pound was strong and things could slip through customs without detected, therefore avoiding customs charges. Nowadays they seem to stop everything. It may still be worth buying from over there though as even with the VAT and admin charge they may still work out cheaper.

[Johno]

Might give that a go, the US price seems reasonable hopefully I can duck customs.

[SGJarrod]

You may remember an old thread of mine where I asked for suggestions on how to make my JM less trebly. To fix this I put a 250K volume pot in my JM and changed the tone pot back to the original (1 meg?). I was pretty sure I soldered everything in the same place as before however I must have bodged something up as now the rhythm circuit doesn't work, it just goes silent when engaged - no biggie though as I don't use it much. Also when I touch the tone knob it seems like there is a loose connection somewhere as the sound goes from sounding like it should, relating to where the tone control is set, to sounding like the knob is always on 10 - when sounding like this turning the pot does nothing. Can anyone suggest what the issue is?

The tone pot issue sounds like you have a cold solder on your tone cap on the main tone pot or the wires on the pot..... if it works but when u touch the tone and it quits, then its obviously a cold solder joint there, I would suspect its the tone cap as when you roll the tone knob down you are bleeding signal to ground(the back of the tone pot) and that is why it gets less bright....if you have a cold solder on the cap then the signal is not getting to ground and therefore sounds like the knob is always on 10

a soldering tip for the back of guitar pots is use a 30watt iron and start at the edge of the solder blob and as the old solder melts slowly roll your iron toward the center of the connection/blob..... I just put a Duncan JB in the Bridge of my Blacktop Jazzmaster and a orange drop tone cap a couple days ago and had really good results with this technique...

For the rythm circuit... I have no idea, I am sure you just have a wire in the wrong place, you will need a schematic or a pic from another JM, I would try to get you picks of mine but mine does not have the rythm curcit in it....

[johnnyseven]

Thanks. The issue with the tone knob is the most pressing at the moment so i'll check that when I next re-string the guitar. I rarely use the rhythm circuit so i'm not too bothered about that, plus at the moment I can use it as a kill switch - Tom Morello stylee.

[SGJarrod]

Merry Christmas






and finally

http://media.photobucket.com/image/fend ... 1268029025

this should be al you need..

[johnnyseven]

Thanks.

Re soldering irons, can anyone recommend a good one to get for this purpose? The one I have is the most budget one Maplin had at the time and can have trouble melting solder sometimes, is it worth paying a bit more and getting a good one with variable temperatures etc?

[SGJarrod]

I am in the States and just use a RadioShack 30watt one....was $8.... I build pedals too and have no issues, I had a 25watt one before and It was not enough for guitar pots and burned thru tips

also, make sure that you are tinning the tip before you start to desolder...aka..put alittle solder on the tip of the iron before you apply it to melt the old solder...the melted solder is what transfers the heat

[Earth]

I've seen a few Duncan JM schematics which seemed to me to be different to what is actually in my guitar. One time I soldered the pickups in and the pickup selector worked the opposite way round to normal, I managed to work out how to fix it though.

This here is a problem in it self, the jazzmaster diagrams are wrong. The SD jaguar diagram don't work either, its missing the 56k resistor. The diagram that comes with a set of antiquities is correct IIRC.

This diagram, although shitty and unclear is correct.


On a side note, I have redrawn the Jaguar diagram in a large, clear and easy to read form and I've been meaning to do the JM too. I'll post it here for you guys when I get around to it.

Here's the Jag one if anyone ever needs it:
(don't miss the grey wire, which represents a white wire and don't forget to join all grounds together)

[johnnyseven]

I am in the States and just use a RadioShack 30watt one....was $8.... I build pedals too and have no issues, I had a 25watt one before and It was not enough for guitar pots and burned thru tips

also, make sure that you are tinning the tip before you start to desolder...aka..put alittle solder on the tip of the iron before you apply it to melt the old solder...the melted solder is what transfers the heat

I've just seen this one on offer - http://www.maplin.co.uk/Module.aspx?ModuleNo=35016 - it has adjustable temperature which sounds usefull, although more than the 30 watt recommended but I guess it's the temperature which is important. What is a good temp for soldering guitar bits and is this worth getting?

[George]

30W is what's recommended. I have an 18W at the moment which can be quite slow but was a cheapey B&Q jobby, and it's shitting the bed. I imagine much hotter than 30W will mean you'll melt wire jackets and other non metal things so 50W (adjustable or not) might be overkill if you're not a pro with a very steady hand.

Have you seen Johnos thread on one that's really cheap...

http://www.shortscale.org/forum/viewtopic.php?t=37755

I'm ordering one for xmas.

[johnnyseven]

That looks good and they have a shop in Watford so I could get my brother to go and pick one up for me. Thanks.

[NickS]

For pots, cables, etc. I'd be tempted by this:

http://www.maplin.co.uk/Module.aspx?ModuleNo=35016

50W temperature controlled iron on offer, down from £29.99 to £19.99
I got my son this a couple of Christmasses back.

[johnnyseven]

Thanks NickS, that's the very same one in my post above. The other chap thought it might be too hot for my purposes, how do you/your son find it?