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Hoffman Amps Forum image Author Topic: pre amp tubes not working  (Read 2166 times)

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Offline marclis

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pre amp tubes not working
« on: August 16, 2014, 07:06:55 pm »
Hello


My first 3 pre amp tubes in my early silverface Princeton reverb amp are not lighting up. I do not have any sound. I've tried multiple pre amp tubes, all the soldering looks strong on the pins. V4 is working fine along with the power tubes and rectifier tube. I was hopeful someone could offer any advice.


I was attempting to install a basic Torres adjustable bias kit and was only on the first step were I just had to move the feedback wire from the extension jack to the speaker jack (to open a hole for the bias pot). The kit asks you to reconnect the speaker and play your guitar to make sure everything is working as normal. This is when I noticed the 3 pre amp tubes not lighting up (they are cold to the touch also). I wished I had played the amp and made sure it was working prior to the kit install (but it was working fine a couple of weeks ago). This is the very first step in the kit and it's very simple and I've checked it over thoroughly.


appreciate any suggestions or things I could test


thanks

Offline sluckey

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Re: pre amp tubes not working
« Reply #1 on: August 16, 2014, 07:12:40 pm »
You likely have a break in the filament circuit wires between the fourth and third little tubes. Break would likely be on the fourth socket or the third socket. Look closely at pins 4, 5, and 9 of both sockets.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline marclis

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Re: pre amp tubes not working
« Reply #2 on: August 16, 2014, 07:34:45 pm »
thanks so much Sluckey! You're right I found it! You made my night!


thanks again

 


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