Please help! My Gibson Falcon is dead, even after a retube.

[BigAlTheBird]

What's up guys?

So I have a Gibson Falcon (1963) that is dead. I bought it on eBay, and the seller has since proven (got it serviced by an amp tech, showed receipt) that it worked when he shipped it. The day I got it, I plugged it in and turned it on, and there was a poof of smoke from a resistor blowing. Turns out one of the power tubes was busted.

So I replaced the resistor, and finally today (after a month), all of my tubes came in. So I fully replaced all of the tubes, and it doesn't work. Bummed me out.

The amp is supposed to use 3 6EU7s, which is what I bought. But the seller originally had 12AX7s in for some reason. So the new 6EU7s don't light up at all, whereas the 12AX7s light up fine. But one of the 12AX7s (in slot 4) has this like surge of power whenever you flip it on (gets super bright instantly and then settles down).

Lastly, the speaker makes ABSOLUTELY no noise. No crackles, sparkles, hum, nothing. So I tried out a different speaker, same story. Since there is absolutely no noise, I'm hoping it's some problem with the speaker wiring. But I don't know how to check that, the speaker wires come out of some box that I don't want to open really. Should I? I know the caps in the power supply section are dangerous, I don't want to meddle where I don't need to.

So I'm pissed off, and bummed. I have no amps, and haven't for almost 3 months now. What could be causing all of this? I'd really love help.

Thanks!

 

[krankguitarist]

Re: Please help! My Gibson Falcon is dead, even after a retube.

IIRC, The 6EU7's have a different pinout than the 12ax7s. That could explain why they aren't lighting up.

Are your power tubes lighting up? If your speaker isn't making any noise at all, it definately isn't getting any signal. As for your speaker being wired wrong...that would seem unlikely. Maybe you could post some pictures of your repair job on that resistor?

 

[BigAlTheBird]

Re: Please help! My Gibson Falcon is dead, even after a retube.

I could post pics, but I know it's fine. Exact same resistor, clean solder joints, not touching any other wires. I know the speaker itself isn't wired wrong, but there is a box that the wires come out of.

To answer your question, with 12AX7s in, all tubes light up. With 6EU7's in (which the amp was originally supposed to run on), they don't light up (4 tubes do, the 6EU7s do not).

I'm so lost on this one! I really appreciate the help though.

 

[Low_fidelity2100]

Re: Please help! My Gibson Falcon is dead, even after a retube.

and you tried it with the 12ax7's after putting in new power tubes right?

 

[Smilemon]

Re: Please help! My Gibson Falcon is dead, even after a retube.

Could the owner have gotten it re-wired to accept 12ax7s?

 

[Low_fidelity2100]

Re: Please help! My Gibson Falcon is dead, even after a retube.

Could the owner have gotten it re-wired to accept 12ax7s?

Thats exactly what I'm thinking. Due to the different pin out, If he Had gotten it rewired to accept 12AX7's, and then ya stick the 6EU7's back in, that could cause a short. Possibly frying something in the process. An if thats the case, that would explain why It doesn't work Even with the 12AX7's (since something else may have gotten fried by putting the 6EU7's in). And would also explain why they Light up, and the 6EU7's Don't. Different pin out, so the 6EU7's aren't getting power to the filament.

Although if thats the case, the seller should have mentioned in the auction that it had been rewired to accept 12AX7's. E-mail whoever ya bought it from, and ask him if he did that.

 

[BigAlTheBird]

Re: Please help! My Gibson Falcon is dead, even after a retube.

It still lights up with the 12AX7s (and yes, this is after the new power/rectifier tubes). It just doesn't make noise.

Also, I can't find a blown resistor or short anywhere. Any way to look faster? None of the resistors are blown though, I'm almost sure I know that.

 

[rashayritto]

Re: Please help! My Gibson Falcon is dead, even after a retube.

know an amp tech?

 

[BigAlTheBird]

Re: Please help! My Gibson Falcon is dead, even after a retube.

know an amp tech?

No, and where I live there are no mom and pop stores. Only GC and the ilk. But my mom knows a dude who owns a store, so I'm going to call him up tomorrow.

*sigh* Did not want to spend money!

 

[The Golden Boy]

Re: Please help! My Gibson Falcon is dead, even after a retube.

Let me know if you need me to take pics- I don't think I'll be able to this weekend (at least until later on Sunday)

 

[Rich_S]

Re: Please help! My Gibson Falcon is dead, even after a retube.

12AX7 and 6EU7 do the same thing (they are both dual triodes with a mu around 100) but they have different pinouts. If it ever worked with 12AX7's in there, then it was converted to use the 12AX7, and 6EU7's will not work from now on. And yes, the seller should have mentioned this.

I don't know if powering it up with a 6EU7 in a 12AX7 socket would hurt the internal components or not - I'd have to look at the pinouts and schematic and think about it a good long while. But I think you'd hear/see/smell it if something fried.

So maybe one of the 12AX7's got busted in transit, too.

I don't thing the "surge" of brightness in one 12AX7 is a real problem - although I would probably swap that tube out first. Do you have additional 12AX7's around, from another amp or whatever? Try swapping the preamp tubes one at a time and see if it works.

 

[BigAlTheBird]

Re: Please help! My Gibson Falcon is dead, even after a retube.

I might have another 12AX7, good idea. And Golden, thanks but I'm not sure at the moment. I think from this point, I'll try a tube swap, but I'm gonna be taking it to a tech.

 

[Fresno Bob]

Re: Please help! My Gibson Falcon is dead, even after a retube.

There's a tech in Redondo that runs a place called Rhythm and Notes. He's on PCH and PV Blvd. He sure takes his time, but does good work at reasonable prices.

 

[BigAlTheBird]

Re: Please help! My Gibson Falcon is dead, even after a retube.

Thanks for the tip! I already made an appointment with (supposedly) one of the better amp techs in LA. Seems like he knows his stuff, and he's not too expensive. I told him the problem, and he said he could fix it in about an hour easily.