GK 800RB - stripped screw threads?

[Joe*]

Just wondered if anyone had experienced this before or had any ideas on how to help...

I've got a fairly old Gallien-Krueger 800RB and was hoping to take a look inside. So I tried unscrewing some of the casing screws (they're tiny, btw). Some of them unscrew... and some of them just keep turning without coming out. Some of the ones that do come out then don't screw back in, so after two/three of these, I stopped as I didn't want to end up with an amp in several unjoinable pieces!

I'm assuming it's a case of the screw threads (NOT the screw heads - these are fine) becoming stripped. I can lever some out with a knife point as I turn the screwdriver, but as I can't be sure that they'll go back in again I don't want to risk taking any more out.

It's not a disaster at the moment, but I'd like to give contacts a clean at some point and if it ever needed repairing I'd be in trouble unless I can sort this out!

 

[Rebmo]

I think you will find the case sheet metal is stripped. I work in a electronice manufacturing business and aluminum and sheet metal case holes get stripped randomly in virgin assemblies even with controlled torque guns. I suspect that the sheet metal case holes have had too much force when tightened in the past and the holes, not the screws are likely stripped. My 2 GK800rbs that I bought used have a couple screw holes stripped too and I see a few non original screws have been used. The solution we use at work is to use an oversized screw that is spec'd by our mechanical Engineer for rework. In most cases it is the same head and screw lenghth with the next size up thread. We also use loctite (the non-permanent bonding) on the case screws to prevent backing out from vibration (I'm pretty sure that would be a good thing for a bass amp). Anyway, maybe Bob G can chime in here and recommend what they use for oversize screws, or you can visit the hardware store and figure out the thread and screw size and try the next larger size. Caution, sometimes the next larger thread size is just too big, so proceed with caution. You can try a metric, sometimes they have an in-between size that works too. Worse case you could tap the hole one size larger but that should not be needed.

Good Luck, I'll let you know if I get around to replacing the few I have and give you the screw size I use.

Reb

 

[Joe*]

Thanks, Reb, that sounds like the most likely scenario... I'll start looking into screw sizes - and blue loctite... thanks again!