Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dearborndave on January 28, 2019, 08:38:43 am

Title: Blues Jr. Rebuild
Post by: dearborndave on January 28, 2019, 08:38:43 am

Hi All,
I'm new to this forum and have a question. I'm doing the Hoffman amps rebuild of the Blues Jr. amp and I am also doing the transformer upgrade at thew same time and here is where my question is. The Allen transformer I am using says It has a center tap for the 6.3 volt heaters, so do I need to use the 47 ohm resistors on the tube socket board? Excuse me if this is a stupid question, but I'm kinda new to all this. I've built amp kits and pedals, and done easy repairs on amps before, but this is the first time I've gutted an existing amp and rebuild it with out a "connect the dots" sort of instructions. Any help would be greatly appreciated. Thanks in advance! Dave

Title: Re: Blues Jr. Rebuild
Post by: sluckey on January 28, 2019, 10:40:11 am

Quote from: dearborndave on January 28, 2019, 08:38:43 am

The Allen transformer I am using says It has a center tap for the 6.3 volt heaters, so do I need to use the 47 ohm resistors on the tube socket board?

It's your choice. Use either method but don't use both. I prefer the real center tap when I have a choice.

Title: Re: Blues Jr. Rebuild
Post by: dearborndave on January 28, 2019, 11:37:40 am

Quote from: sluckey on January 28, 2019, 10:40:11 am

Quote from: dearborndave on January 28, 2019, 08:38:43 am

The Allen transformer I am using says It has a center tap for the 6.3 volt heaters, so do I need to use the 47 ohm resistors on the tube socket board?

It's your choice. Use either method but don't use both. I prefer the real center tap when I have a choice.

So do I just omit the 47 ohm resistors and run the green outputs from the transformer to the heaters and the center tap to ground? Like I said I'm new to this so I need everything explained to me. Sorry for being a pain...

Title: Re: Blues Jr. Rebuild
Post by: sluckey on January 28, 2019, 11:44:54 am

Quote

So do I just omit the 47 ohm resistors and run the green outputs from the transformer to the heaters and the center tap to ground?

If you want to use the real center tap then yes.

If you rather use the resistors then just tape the end of the real center tap wire, tuck it out of the way, and pretend it doesn't exist.

Title: Re: Blues Jr. Rebuild
Post by: dearborndave on January 28, 2019, 11:52:28 am

Thanks Sluckey, I kinda figured it out myself by lookin' at some old Fender schematics that used a center tap on the heater circuit. I will definitely use the real center tap. I figure if it's there I might as well use it! Thanks again!