Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: makingnoise88 on November 28, 2016, 07:12:21 pm
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I've built a few amps now and I've noticed that I'm not getting the 3.3v ac per side on any of them really. The latest one I built was a 5f6a and I've been doubtful I'm putting out a full 50 watts. I'm measuring 3.0 on one side and 2.6 on the other!
I'm measuring by clipping my common lead to the chassis and then the other lead to each pin. Is the best way to do so?
And with the one lead that is 2.6 I've re flowed the solder and doesn't seem to change.
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The best way to measure filament voltage is with one probe on one socket pin and the other probe on the other socket pin.
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Also, 5V is good enough.
What is the wall voltage of THAT wall outlet; and plate voltage? Is this a true 5f6a built to actual spec? What iron?
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Slicker, that was it. Full 6.3 when I go about it that way!
Jjasilli, it's the Hoffman kit.
PT is the mojo762
OT is new sensor NSC018343
I'll attach a picture for good measure!
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That's Sluckey.
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Haha dang auto correct!
I'm sorry Sluckey! I didn't even notice that it had changed it.
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Sluckey,
When reading the rest of the voltages on each pin, common to the chassis is what I'm doing. Is that okay or is there a better way?
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When reading the rest of the voltages on each pin, common to the chassis is what I'm doing.
That's fine for 99.9% of the voltage checks.
The reason that your filament voltage readings were not equal when measuring to chassis is likely because your 100Ω artificial CT resistors are not exactly equal value.
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The best way to measure filament voltage is with one probe on one socket pin and the other probe on the other socket pin.
He already responded to that question :)
From pin to the other pin... say a 12AX7 pins 4/5 on one probe and pin 9 on the other. Other tubes will list what they're using for the heaters.
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I'm going to add a picture of all my other voltages.
Is there a resource anyone knows of that would tell me what voltages I'm looking for?
I've looked but can't seem to find anything.
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There are easily a dozen voltage readings on just a plain old Fender schematic, out of Doug's library. Those are the important ones, for sure.
I have not used it but isn't there a section of the library "post your amp voltages here" with a spreadsheet (like you have) of every pin, every tube? Perhaps another forum member can point to this.
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Oh awesome! I'll try and find it.
I've been just using my phone so I'll switch to the computer. Maybe I'll find it that way!
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It's here:
http://el34world.com/charts/valve/ValveDataIndex.php (http://el34world.com/charts/valve/ValveDataIndex.php)
~phil
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I added My voltages! But not I'm not sure how I know if someone has looked at them or how it works lol So i guess I'll wait on that one!
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I think the idea was to look at voltages for a comparable amp and see. I don't know if you can link us yours, but I think you already have shared them here. If you can look at an identical amp or one with very similar setup it should show you what expected voltages are.