Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: sclinchy on September 10, 2024, 01:40:23 pm

Title: AA1164 Startup Problems
Post by: sclinchy on September 10, 2024, 01:40:23 pm

I just went through my previously functioning Hoffman AA1164, resoldering, replacing some wiring, etc.  I’ve started it up with just the rectifier tube installed, and I’m getting voltage readings that don't make sense to me. I’m hoping to get some insight into where I might have gone wrong.


This is what I’m seeing:

Capacitors [/t] [/t] Y 440 [/t] X 470 [/t] U 475 [/t] O 470 Rectifier[/t] [/t][/color] 2 [/t][/color] 4,6 [/color]V5, V6[/t] [/t][/color] 3 467 [/t][/color] 8 0 [/color]V1[/t] [/t][/color] 1 465 [/t][/color] 3 0 [/t][/color] 6 465 [/t][/color] 8 0.02 [/color]V2[/t] [/t][/color] 1,6 476 [/t][/color] 3,8 0 [/color]V3[/t] [/t][/color] 1 467 [/t][/color] 3 467 Thanks for any and all help!

Title: Re: AA1164 Startup Problems
Post by: Dave on September 10, 2024, 01:55:40 pm

At a glance, it looks like it's just because there is no load.


I don't know what all the X's and O's equate to, but you've got similar voltages all down the chain. Seems normal to me. When you start loading them down with tubes, they will seperate.


Dave

Title: Re: AA1164 Startup Problems
Post by: HotBluePlates on September 10, 2024, 04:10:02 pm

As Dave said, nothing is visibly wrong.  You will need to install tubes to have some current drawn from the power supply, which will also drop voltages (and make cathode voltage rise due to voltage-drop across cathode resistors).

If you're concern there's a wiring fault waiting to burn something up, consider making & using a "lightbulb limiter."