Gibson GA-40

[Tripower455]

Have any of you guys messed with one of these? My friend's brother has owned a '54 GA-40 "Les Paul" amp for about 30 years. It hasn't worked since he got it, and has been sitting in a closet ever since. He was over a while ago, and when he saw my homebuilt amp collection, asked if I'd look at it. It played, but had a nasty, spitty fizz type tone that would die off immediately after playing. I fired up the trusty fluke, and started checking impedance and voltage.

This thing is like a rats nest inside, and the ONLY documentation I could find for this thing was a schematic that looked like the amp sounded..... After a few hours of trying to figure out what was what (now I KNOW why Dave Reeves built Hiwatts the way he did...... He probably cut his teeth on amps like this!). Troubleshooting a Hiwatt is childs play compared to this thing.

After reading up on these things, most guys say just to replace pretty much all the caps, so I did. They were mostly those wax dipped jobs. I put in a mix of stuff I had lying around. I also picked up some new tubes, all NOS except the 6V6s and the PI, which is a 6sn7.

Anyway, I found a few dead resistors and some way out of spec ones. I replaced them and it fired right up. I didn't have a chance to mess with it much, but it sounded great at low to medium volume, and the tremelo even works! Tomorrow, it's getting cranked.

He's gonna be so happy that this thing works again. The guy is short on cash, and didn't want to spend a ton on it. I actually owe my friend (his brother) a favor or 2, so I am not even gonna charge him for the parts I replaced.

I gotta get some pics with my R4.......

[OldSchoolDave]

I've got an old (brown) Skylark Tremelo (GA 5T). While there isn't quite enough going on to constitute a "rat's nest", it does deploy rather "freeform" wiring.

Dave

[Tripower455]

I've got an old (brown) Skylark Tremelo (GA 5T). While there isn't quite enough going on to constitute a "rat's nest", it does deploy rather "freeform" wiring.

Dave

Freeform is an understatement. Just doing voltage checks is a major PITA, because so many wires try to occupy the same place! It does sound and play great though!

[mhuss]

Yeah, the Gibbys are great sounding little amps, and were quite a bargain on the used market -- until everyone started jumping on the bandwagon a couple years back.

--mark

[Tripower455]

Yeah, the Gibbys are great sounding little amps, and were quite a bargain on the used market -- until everyone started jumping on the bandwagon a couple years back.

--mark

Yeah, I looked around to figure out the value. Wow..... This one is all there, but nowhere near perfect. The guy who owns it just wants a player, so I didn't go all out trying to "restore" it. I just got it safe and operating. I might try building something along these lines. It KILLS with P-90s...... The "microphone" channel is my favorite...
Now that I got it working, I need to go in a clean up some stuff.

I get to keep it for a few months until the guy comes down to visit his brother. Enough time to make sure it's fixed!

[thefatcyclist]

link to my brilliant amp tech, for interest.
http://www.dennismarshall.co.uk/contact.htm