Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: JGk on September 11, 2019, 09:34:37 pm

Title: 1951 Valco Supreme Model 510-1B Field coil wireing diagram wire color code
Post by: JGk on September 11, 2019, 09:34:37 pm

Hi all still working on the Valco. Cleaned up the power bar wiring had to replace the terminal strip as it was cracked I must have gotten a wire from the Field coil speaker wrong ended up with a high pitched oscillation was wondering if anyone had any experience with wire a field coil speaker JK

Title: Re: 1951 Valco Supreme Model 510-1B Field coil wireing diagram wire color code
Post by: sluckey on September 11, 2019, 09:53:43 pm

I've wired quite a few field coils back in my younger days. I would just suggest looking at the schematic. Everything you need to know is on it.

     https://el34world.com/charts/Schematics/files/Valco/Valco_510_1b.pdf

Title: Re: 1951 Valco Supreme Model 510-1B Field coil wireing diagram wire color code
Post by: JGk on September 12, 2019, 08:48:39 am

Thanks that schematic is different than the one I've been working off of the Valco I have has 2 inputs. JK 

Title: Re: 1951 Valco Supreme Model 510-1B Field coil wireing diagram wire color code
Post by: PRR on September 12, 2019, 12:28:36 pm

> that schematic is different ....I have has 2 inputs

Is the speaker end about the same?

The factory can change one end and leave the other the same. Like the old days: Chevy and Ford made 2-door 4-door station wagon and posh pickup trucks all on the same front end. For repair you only need to look at the end which is sick.

Title: Re: 1951 Valco Supreme Model 510-1B Field coil wireing diagram wire color code
Post by: JGk on September 14, 2019, 08:35:55 am

Thanks for the info. Schematic appears to be the same past the 3 inputs. Sorted out the speaker hookup, replace the the 270K ohm resistors and .02 caps in the power section. Changed the 2 wire AC cord to a 3 wire and removed the death cap. Now I have a major high pitched oscillation when I power it up. I haven,t done anything in the input PI section yet. Anyone have any thoughts on the oscillation problem. Thanks JGK

Title: Re: 1951 Valco Supreme Model 510-1B Field coil wireing diagram wire color code
Post by: sluckey on September 14, 2019, 09:33:25 am

Are you actually using a field coil speaker? If not, did you replace the field coil winding with a 1K 10W resistor?

For squeal, replace filter caps. If still squealing pull the tubes one at a time to try to locate where the squeal originates. I would start with preamp, then PI.

Title: Re: 1951 Valco Supreme Model 510-1B Field coil wireing diagram wire color code
Post by: JGk on September 15, 2019, 06:44:11 pm

Thanks for the help got it up and running, changed filter caps, most internal caps and resistors and the volume pot. Sorted out the speaker and field coil. Not really familiar with this amp and I went through it for a friend. Isn't really that loud or clean as I have nothing to compare it to will do a bit more tinkering.    JGK