Gibson Falcon Amp.

[zequ]

Hi all, I have an old Falcon from the 60's i think. It has 4 12ax7 and 2 EL84.

 

The tremolo on it doesn't work, it acts more like a volume. When the knob is turned up, the sound diminishes.

 

I notices some of the capacitors near the tremolo oscilator tube are very dark red instead of bright orange.

 

Just want to bring the amp back to it's original condition.

 

Also I would like to know how to connect up the footswitch pedal to this as there was never an original pedal.

 

This amp has been in my family since it was bought.

 

Here is a bad copy of the schematics : http://www.schematicheaven.com/gibsonamps/falcon.pdf

 

Thank you.

[rl1968]

Hi there, I am currently in the process of restoring a 1964 Mercury I Amp and I found a website that has much easier to read schematics. I hope the link helps you out. I did restore an old 1965 Univox U45B amp and replacing the caps fixed the non-working tremolo on it.

 

http://www.el34world.com/charts/Schematics/gibson/FALCON.pdf

[zequ]

Awesome schematic! All i had was that fuzzy jpg one! Outstanding. The orange drops around the tremolo tube are a dark red color and a friend says they definitely need replacing. I will check them out asap.

 

If anyone is interested, here is a parts list for said Falcon. Flip side of the schematic.

 

http://www.harpamps.com/gibson/pg_0316.jpg

 

Thanks again!

[Two15s]

Just a quick thought. Before you start changing caps have you checked that transistor Q1 hasn't blown and short-circuited the collector to emitter? That would give exactly the symptoms your describing.

 

[zequ]

Just a quick thought. Before you start changing caps have you checked that transistor Q1 hasn't blown and short-circuited the collector to emitter? That would give exactly the symptoms your describing.

 

:)

 

Hi Two15s,

 

The said transistor has 8393K stamped on it. I've searched Google but have not found it anywhere.

 

I'll look around on how to check that (maybe do a ohm check on the collector to emitter?).

 

Seeing as the channel mix goes into that Q first, it would make sense.

[Two15s]

Yes you can just use a DVM to measure a short but if it's just leaky you might be better off with an old analogue meter, they tend to use a higher test current.

 

The 8393K is the end of Gibson's factory part number 991-008393. Gibson will probably tell you what the proper replacement is but, just for fun, I tracked down the same number in a Lowrey organ parts list. Lowrey were bought by CMI in the late fifties so the similarity can't be a coincidence.

 

Lowrey part number 991-008393-000 = transistor, NPN, 2n2924.

 

This is a small signal device usually in a three pin plastic package. Anything like yours?

 

[zequ]

Yes, that transistor is a black plastic package, and it's wired onto a small terminal strip on the tremolo pot. I am not too sure if it's the caps or the Q that is the problem. I will source out the 2n2924 you mention as it will most likely be the most readily available part and try swapping it out. That would make the most sense at the moment. Thanks for all your help guys!

[rl1968]

FYI: On my Mercury I Amp it did turn out to be a cap that was keeping the tremolo from working, but it wasn't a bad cap, it was actually one missing from the circuit. On the Mercury I schematic, it was C9, a .01 cap next to the .022's. I did replace the .022's and installed the .01 where it was supposed to be. Now the tremolo works and sounds great.

 

I just wanted to let you know, you never know who worked on it before you aquired it, and how qualified they were to be in there.

[BOBRVT]

I can't access the print, but I'm confused. The Falcon(GA19RVT), has 2x6V6, and 6eu7's and a 6C4. No el84's, sounds like a GA17 Scout. If you have a Falcon with 84's, I don't know of it. Transistors? What does the cabinet look like? Something's goofy. Probably me...

[BOBRVT]

That's a transistor under the tubing? with that icon? Isn't it a photo coupler for the trem?