Intonation screw problem

Heavy Jerk

Member
Messages
5
Hey,

I have a Jackson COW7 which has JT390-7 bridge in it (you adjust intonation on the side that faces pickups with a Philips screwdriver, and on the other side of intonation screws facing away from the pickups are hex nuts), so it's a Tune-O-Matic type of bridge.

I tried to do a guitar setup a couple of days ago and noticed that screw head on the low B string saddle has been stripped, so I am unable to adjust it.

How can I remove it as safe as possible in order to replace it?
Oh, and if someone by any chance would know the saddle length screw size on this type of bridge (JT390, lot of Jacksons have it)? Can I use Fender Vintage Strat 4-40 X 5/8
screws ('cause that's all I could find in local guitar shops)?
This guitar is made in Japan, so I recon they used metric screws, that's why I ask. Maybe I should try M3 x 15 mm screws if 4-40 won't fit. And where can I find hex adjusters (nuts that face away from the pickups)?

Regards
 
Last edited:

Heavy Jerk

Member
Messages
5
Hey thanks on your reply. :)

I've found the right screws, but now the problem is I can't remove the old saddle, because I can't remove the hex nut which is on the other side of the intonation screw. I tried applying some heat to it, since I've read it has self lock plastic part, but it won't give in. As I'm turning the screw, the nut is turning along with it too. Any tips on that?
 

B. Howard

Gold Supporting Member
Messages
1,211
Sometimes these things get virtually welded together from sweat. Sometimes the only option is to carefully grind the head or the nut off with a rotary tool and carbide burr. Of course you will now need the matching nut as well.
 

Heavy Jerk

Member
Messages
5
Eh :-(
Since that hex nut is not a regular nut (it has sort of a collar) I do hope that grinding won't be needed.
 

walterw

Platinum Supporting Member
Messages
38,723
you might be better off leaving it alone and just using the hex nut to adjust intonation.

this is the gotoh setup; you can indeed remove it with soldering iron heat, but it's still a pain, and nothing else besides a screw from another gotoh just like it will fit.
 

Mike9

Silver Supporting Member
Messages
10,960
A lot of times the nuts are thread locked on (Loctite). Put a soldering iron to it and it should melt the Loctite enough to come loose. Works for me most of the time.
 

Heavy Jerk

Member
Messages
5
^^Heya, I tried that already, although I am not sure if I applied enough heat. How long should I hold the iron tip on the hex nut before it backs off? I have a 25W iron.
 

Mike9

Silver Supporting Member
Messages
10,960
Not that long - it's a small nut you just want to melt the loctite.
 

Heavy Jerk

Member
Messages
5
Thanks!
I was wondering, if I am unable to find those mini hex nuts, couldn't I use those e clips that come with saddles instead?
example (the pic is not mine):
 

walterw

Platinum Supporting Member
Messages
38,723
doubtful, the screws likely aren't designed with grooves for those to clip into.

i strongly suspect that nothing besides the original parts will retrofit.
 




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