Amplifier Gurus I Need Help Finding A Schematic

[Nostalgic Distortion]

Hey guys... So I have a old Valco/Airline 62-9020B tube bass amplifier that someone has mutilated but not past the point of no return & I’d really like to get it running as it should again! As of right now it’s blowing fuses as soon as I turn it on but I was told it was working just before I got it, probably not very well though??? I’ve come across some photos of others & it would seem at the very least I’ve got some extra parts in mine. Also I’m pretty sure that it was soldered by a child?


Anyway it’s a pretty simple little amp & I’m already buying all new caps for my Bassman so it wouldn’t be a big deal to buy a few more items for that while I’m at it but for the life of me I can’t find a schematic for it anywhere!!! While it’s not super complex I’d rather avoid poking around blind so any help or information about it you guys could offer would be greatly appreciated!!!!

Thanks!!!

[Gtrjunior]

Re: Amplifier Gurus I Need Help Finding A Schematic

I’m certainly no tube amp tech but I can tell you that a bad power tube will blow a fuse at startup.
If you haven’t already, maybe start with a fresh set of power tubes?

[Nostalgic Distortion]

Re: Amplifier Gurus I Need Help Finding A Schematic

I’m certainly no tube amp tech but I can tell you that a bad power tube will blow a fuse at startup.
If you haven’t already, maybe start with a fresh set of power tubes?

Oh yeah, I’ve pretty much already gone through any of the easy fix stuff. At this point I’m pretty certain one or more of the internal components are failing. Also it may have something to do with those two capacitors wired in series on the switch because they certainly don’t belong there? Also the cathode resistor is looking a little “baked”, as are some of the rectification diodes, & I’ve been told that the big can capacitors on these things we’re apt to fail as well, so it’s hard to narrow it down to any one thing, at least with my skill set anyway, LOL......

Besides since it’s such a simple circuit I think I’m pretty set on doing a total overhaul and replace everything but the iron (providing its good) with nice modern components? If I’m going to do it I want something that will be reliable & I’m a big pedal fan anyway so a decent clean tone is most of what I care about. Although I’m sure it will have some decent breakup as well once it’s turned up. It is after all basically just a cathode biased Bassman.....

[shawn7oh]

Re: Amplifier Gurus I Need Help Finding A Schematic

Get a duncan convertible 100. you can find them at ebay and guitar center used for around 400-500. You have to play with the tubes but when you get the right combination, jackpot! I'm using a vintage 12AT7 V1 and it's unbelieveable. You'll thank me for this. The airline is a beautiful gizmo side project, but at the end of the day, you're gonna want to dream and rock. I have been playing since the early 70's, tried almost everything out there, it's the number 1 underrated amp ever made, and near the tops in sound, if not the top! I use the clean channel with pedals. Use it with a strat. In case you think I'm just not on it, first guitar i bought was a national valpro by valco, and i have an eastwood jetson jt, lol. i've used the old amps like that, they're fun, but you can get that out of a convertible if you want, and then, you can get a bunch of serious other stuff that blows fenders away in every category, lol. You've not heard an amp like that unless you tube it yourself.

[shawn7oh]

Re: Amplifier Gurus I Need Help Finding A Schematic

That's a sweet piece to be sure, but if you're into vintage, snap up a convertible 100 combo, and contact me re the tubes/modules if you have q's.

[Nostalgic Distortion]

Re: Amplifier Gurus I Need Help Finding A Schematic

Yeah man, Convertible’s are nice amps when they are running properly for sure!!! Unfortunately I don’t think I’ll be buying one anytime soon? I’ve already got over a dozen really great Fender n Marshall style PTP/Hand Wired clones, including some real deal vintage Fender’s, a recent JCM-800, hand wired VOX AC-15, & a 120W 6505 that I haven’t touched in several years. All of which I’m very happy with...

This thing was just in the basement of my buddies house when he bought it & he gave it to me. I just want to get it running well again because currently I’ve got absolutely nothing into it & it sounds like a fun thing to do? Not because I’m looking for a great vintage amp that I don’t already have or because I feel like I’m missing something.....

[allbutromeo]

Re: Amplifier Gurus I Need Help Finding A Schematic

If what I'm seeing online is correct, that's the same circuit as the early 64-65 Supro Thunderbolt when they still used the rectifiers. This site has a link for that schematic as a PDF.

http://www.angelfire.com/mech/beansamps/supro/supro.htm

[Nostalgic Distortion]

Re: Amplifier Gurus I Need Help Finding A Schematic

If what I'm seeing online is correct, that's the same circuit as the early 64-65 Supro Thunderbolt when they still used the rectifiers. This site has a link for that schematic as a PDF.
http://www.angelfire.com/mech/beansamps/supro/supro.htm

Actually this one is diode rectified however I believe that you are correct about it being the same circuit as the Thunderbolt....

Thanks!!!!!!