Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: six_eight on March 28, 2013, 11:04:31 am

Title: Schematic for National Glenwood 2x12
Post by: six_eight on March 28, 2013, 11:04:31 am

A friend just came into possession of one of these.  It sorta works.  The trem channel is dead, and it's humming terribly.  None of the knobs work on the normal channel.  Sounds like the volume is stuck on 1.  Most of the print is worn away, so I'm not even sure what all the knobs and switches do.  Anyhow...I was hoping someone here had a scheme for it.

Title: Re: Schematic for National Glenwood 2x12
Post by: smackoj on March 28, 2013, 04:02:17 pm

I have not seen that model name before 'Glenwood'?  Have you been able to date the amp? Does it use octal socket preamp tubes like 6SL7, 6SQ7?  If it was built by Valco of Chicago which I know at least 'some' of the National amps were, you should be able to find the schematic by looking at the tube layout, looking at the guts and checking the schematics in Doug's library. It could be under several different names all made by Valco like Gretsch, Airline, Wards, National, Supro, Oahu and maybe a few others.

 :icon_biggrin:

Title: Re: Schematic for National Glenwood 2x12
Post by: six_eight on March 28, 2013, 05:10:42 pm

Thanks.  I think I found it.  It looks to be the same as the Valco 510-80.

Title: Re: Schematic for National Glenwood 2x12
Post by: six_eight on March 28, 2013, 05:13:24 pm

What's the purpose of the SPST switch coming off the mains?  It connects a .01uf across the common and neutral and turns a light on and off.