| Author |
Topic: Old National Amp |
Joe Kaufman
From:
Lewiston, Idaho
|
Posted 6 Jun 2021 12:01 pm |
|
I need to clean up this amp that seems to have spent the last 30 years on a barn shelf. Can anyone offer tips? I was trying to figure out the model (maybe find the schematic)?
Thanks!
 |
|
|
|
Brian Hollands
From:
Geneva, FL USA
|
Posted 6 Jun 2021 1:27 pm
|
|
Schematics... https://el34world.com/charts/Schematics/files/valco/Valco_Schematics.htm
Looks like a model 50 but the tube complement listed doesn't match what I see in the amp.
It's a field coil amp so you'll want to read up on tjose and the use of an isolation transformer with it.
Looks like a fun project.
_________________
'81 Sho-bud LDG, 2 EMCI's |
|
|
|
Jerry Overstreet
From:
Louisville Ky
|
|
|
|
Jamie Howze
From:
Boise, ID
|
Posted 6 Jun 2021 2:12 pm
|
|
| Don't plug it in and turn it on until it's been gone over by a tech. The filter caps are surely bad and turning it on may damage the circuitry. I've seen too many "found" old amps damaged this way, 'cuz it really is everyone's instinct to turn it on and see if it works! |
|
|
|
Donny Hinson
From:
Glen Burnie, Md. U.S.A.
|
|
|
|
Joe Kaufman
From:
Lewiston, Idaho
|
Posted 7 Jun 2021 10:09 am
|
|
Thanks everyone. The links to the schematic are very helpful! I am sorry that one of the photos is rotated funny, I don’t know how that happened since the original is rotated fine.
Is there any other tips about an amp like this? I am hoping it will be a good match for the 1940s-1950s string through Supro or fender trapezoid pick ups. |
|
|
|
Joe Kaufman
From:
Lewiston, Idaho
|
Posted 9 Jun 2021 9:44 am
|
|
| I am still waiting for the time to work on it. I am guessing it will be similar to a Fender Champion of the 40s with similar power of the Deluxe. |
|
|
|
Ron Funk
From:
Ballwin, Missouri
|
Posted 9 Jun 2021 5:26 pm
|
|
You gotta love those old amps with just a volume control knob
No tone knob(s) at all -
It's all in the hands! |
|
|
|
Stephen Cowell
From:
Round Rock, Texas, USA
|
Posted 10 Jun 2021 12:28 pm
|
|
Any time you get an amp, old or new... pull the fuse and make sure it's not way too big. I can't count how many times I've found automotive 20A fuses in equipment... real recipe for smoke.
I was gonna say that looks like a hot-chassis amp... but apparently the power transformer (PT) is right under the speaker magnet... which is, of course, an electromagnet, 'field-coil', doubles as the power supply filter choke. If you take that speaker out then at least put a power resistor in place of the magnet circuit... it's not good to just short it out.
If you get an old amp that doesn't have a PT, and the tubes are strange numbers that add up to 110V, then don't use the amp without an isolation transformer... it's a 'hot-chassis' amp and can hurt you otherwise.
_________________
New FB Page: Lap Steel Licks And Stuff: https://www.facebook.com/groups/195394851800329 |
|
|
|
