I have been working on this for several weeks, and I am "finished" now.
The amp fires up fine, all normal voltages are present, nothing out of the ordinary except for:
1. The amp gets full B+, and normal cat voltage right away. But it will not pass signal for about 2 minutes. What can cause that.?
2. I triple checked my pot wiring, and I swear it is correct, but the volume knob decreases when CW, and increases when CCW. Seems strange. And.....I cannot get the volume anywhere near "off". The volume is pretty loud, regardless of the knob position.
Do you guys have any idea what I may have dome wrong.?
At the moment I have the Trem Tube (V3) removed. I thought it would be easier to start with just the pre, PI, and out-put for the moment.
Thank You
http://www.el34world.com/charts/Schemat ... 12_6v6.pdf
http://i111.photobucket.com/albums/n143 ... 123005.jpg
http://i111.photobucket.com/albums/n143 ... 123006.jpg
http://i111.photobucket.com/albums/n143 ... 123007.jpg
http://i111.photobucket.com/albums/n143 ... 123008.jpg
New build help
Moderators: pompeiisneaks, Colossal
Re: New build help
i guess you know, you're never "finished."
If the pot seems backwards, swap the outer lug wiring and see if it works in the correct direction. If it does, that's that. While you have the wires disconnected, meter the pot from each outer lug to the wiper. Rotate the pot. At max it should be close to its rating, and min it should be zero. This will tell you if the pot is bad.
As for the 2 minute thing, it suggests that something has to heat up before it works. I'd be looking for a bad/cold solder. It could also be a filter cap that isn't charging as quickly as it should, but I think not.
If the pot seems backwards, swap the outer lug wiring and see if it works in the correct direction. If it does, that's that. While you have the wires disconnected, meter the pot from each outer lug to the wiper. Rotate the pot. At max it should be close to its rating, and min it should be zero. This will tell you if the pot is bad.
As for the 2 minute thing, it suggests that something has to heat up before it works. I'd be looking for a bad/cold solder. It could also be a filter cap that isn't charging as quickly as it should, but I think not.
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Super_Reverb
- Posts: 188
- Joined: Tue Dec 21, 2010 6:28 am
- Location: Indianapolis, USA
Re: New build help
Suggest measuring plate and cathode voltages from input to output. In other words, trace the signal path to verify if voltages look correct. If you have a way to inject AC, that is good to check also after you verify DC bias on all stages. I have used a tuner output with a pot to control volume.
Do this in failed state and repeat when it starts working. The difference should lead you to your answer.
You learn alot about electronics when you find and correct problems.
cheers,
rob
Do this in failed state and repeat when it starts working. The difference should lead you to your answer.
You learn alot about electronics when you find and correct problems.
cheers,
rob