Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Locrian99 on April 08, 2024, 05:48:17 pm

Title: Is this most likely a bad socket
Post by: Locrian99 on April 08, 2024, 05:48:17 pm
Hey all,

Friend of mine brought this fender super 112 to me.   States turns on doesn’t pass signal.   

Confirmed…

No output at pre amp out of effects loop.    I hook my phone signal generator up to it and i can hear the wave coming from the speaker but it doesnt sound amplified.   Through my scope at v2b pin 2 i have a signal of around 10vpp, pin 1 i have .5 vpp.   Tried a known good 12ax7 in its place no change.   Removed old
Solder from socket and pcb applied new.  No change.    The way this board is in here changing the socket is going to be a lot of fun so just wanted a second opinion if that would be the next route or a suggestion on testing the socket?  Is just checking continuity from pin to the pcb alright?

Thanks

https://elektrotanya.com/fender_super_112_rev.a_sch.pdf/download.html
Title: Re: Is this most likely a bad socket
Post by: Dave on April 08, 2024, 05:59:47 pm
Not nearly enough information to make that determination. One thing that would help is some high res pics of the board/boards.


Dave
Title: Re: Is this most likely a bad socket
Post by: Locrian99 on April 08, 2024, 09:14:15 pm
Quote from: Dave on April 08, 2024, 05:59:47 pm
Not nearly enough information to make that determination. One thing that would help is some high res pics of the board/boards.
Hey thanks for the response.   Ill try and get some pics tonight the way they have these component side down and the wiring makes everything a real pita.

From the schematic could an issue with the switching system cause that triode to not amplify.   Seems like that is what is happening which i guess doesnt point to a bad socket since the signal is making it through.

If he wasnt for whatever reason so in love with this thing i’d tell him its not worth the headache lol. 

Title: Re: Is this most likely a bad socket
Post by: AlNewman on April 08, 2024, 09:40:37 pm
Try measuring voltages at all tube pins.
Title: Re: Is this most likely a bad socket
Post by: Locrian99 on April 08, 2024, 11:57:14 pm
Quote from: AlNewman on April 08, 2024, 09:40:37 pm
Try measuring voltages at all tube pins.

I shouldve down this in this first place.   

Load resistor toasted, replaced and works great.    Thank you!
Title: Re: Is this most likely a bad socket
Post by: AlNewman on April 09, 2024, 12:46:15 am
Cool.  I'd still go through everything and make sure it's within spec.  That's a pretty good schematic.
Maybe it was just an anomaly that the load resistor went, or maybe it points to a different issue?