mid sixties gibson - rotary power switch

[smolder]

Hey Guys,

I picked up a GA-35 RVT Lancer a while back that is like brand spanking new. I wanted to put in a three prong power cord, remove the death cap, and it made sense to me to disable the polarity function (like I do on my fenders). The power switch is a rotary four stop with: off | standby | on | on .

So I wired in the new cord with white and black where they were previously and the green on the closest mount of the PT. I then removed the death cap between the rotary switch and ground. Now I blow a fuse when I switch from standby to on.

Does anyone have a wiring diagram for this switch? This seems like a simple update that tons of techs would have done and I can find no information about it. Worse... I can not seem to wrap my head around how this switch works and how it relates to the schematic.

Any help would be greatly appreciated.

[sluckey]

Recheck your wiring. Wire it according to this schematic but omit the cap.

http://www.schematicheaven.com/gibsonamps/ga35rvt.pdf

[smolder]

Thanks Sluckey.... I think that is where I'm having difficulty... translating that schematic to the switch. It has the switch drawn in 4 different places. I will try diagraming how it is hooked up now an continue attempts to cross reference with the schematic.

Recheck your wiring. Wire it according to this schematic but omit the cap.

http://www.schematicheaven.com/gibsonamps/ga35rvt.pdf

[sluckey]

So I wired in the new cord with white and black where they were previously and the green on the closest mount of the PT. I then removed the death cap between the rotary switch and ground. Now I blow a fuse when I switch from standby to on.

Something else must have happened while you were doing this. Doing only what you said would not cause this.

[smolder]

So I wired in the new cord with white and black where they were previously and the green on the closest mount of the PT. I then removed the death cap between the rotary switch and ground. Now I blow a fuse when I switch from standby to on.

Something else must have happened while you were doing this. Doing only what you said would not cause this.

You are correct. I also replaced the two 20/20 filter caps and the 20uf bias cap. Pretty much red to red and black to black drop ins.

[smolder]

here is what I have and it seems consistent with the schematic. But like I said... the way the schematic is drawn is not easy (at least for me) to map it to the switch.




EDIT: Tried to get the full size pic to work, but for some reason it refuses to.......maybe try reloading it to photobucket.

[smolder]

replaced with a more stealth jpeg and a png below:

[sluckey]

I also replaced the two 20/20 filter caps and the 20uf bias cap. Pretty much red to red and black to black drop ins.

This could definitely cause the symptoms you describe if something went wrong. Recheck your work.

[smolder]

I also replaced the two 20/20 filter caps and the 20uf bias cap. Pretty much red to red and black to black drop ins.

This could definitely cause the symptoms you describe if something went wrong. Recheck your work.

OK... I will try putting the old caps back in this evening to see if the amp fires up.

[smolder]

ack... good lord. So if the 25/25 dual caps I put in were only 25 watt instead of 450... that would probably do it, right?

[sluckey]

We need to see a picture.

[smolder]

uh... no we don't.

[RicharD]

A picture is worth a thousand words.  If you're concerned someone will make fun of your work, don't be.  This group is the most helpful & polite bunch on the internet.  You'll get useful constructive criticism that you can learn from.  Chances are somebody might be able to spot an error from a high resolution picture.  Cheap shots are so far and few between here because we all love tube amps. 

[PRR]

> caps I put in were only 25 watt instead of 450...

Watts? There's no watts on a cap.

400-some VOLTS on a 25V cap.... well, I tried to put 1,200V (oops) on 35V caps once, and nearly blew-out the building.

[smolder]

I can put pictures but they won't really show anything. I mistakenly ordered 25/25 F&T's without looking at the voltage (not wattage). I'll throw a pair of 22uf 450's in each place and shoot what it looks like. Gibson layouts are really a mess btw. The caps did not blow... I was blowing a fuse before that seemed to occur.

I'm rarely embarrassed about making mistakes... that's how we learn, but when they are so obvious that we look right by them I tend slap myself up on the head. My response was more a riff on the 'we need pictures' call.

[sluckey]

That 25/25@25v will probably work for the bias caps, although I'd be more comfortable with 50v-100v rated bias caps. They definitely won't work for the B+ caps. Did you put them in the B+ line?

[smolder]

That 25/25@25v will probably work for the bias caps, although I'd be more comfortable with 50v-100v rated bias caps. They definitely won't work for the B+ caps. Did you put them in the B+ line?

Yes, in this amp there are two 20/20 450v electrolytics that are used for filtering. There is another 20uf that sits on the bias pot (at least that is what I think it is - it's not on the schematic). There are a pair of 25uf 25v caps that sit right off the filter caps in the power section as well. I am going to leave those for the time being. When I got the amp is was lacking some volume and had a slight hum... and the electrolytics in the filter section were original.

[smolder]

sorry it took so long for picks. This is the final (and fully working) cap job. It is not the most elegant. Had I to do it over again, I would likely use a 4x20 cap can with a mount. But this works, is sort of in keeping with Gibson's tendency towards flying components - and it should hold up just fine.

Thanks for all the help guys. I really do appreciate it.

[birt]

looks very clean