5e3 with some low level hum

filthytone

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OT primary voltage losses 37V and 24V seem way too high! If first tube bias current is 30mA it makes that primary half resistance 1200 ohms when they usually are 150...200 ohms each half for typical Deluxe OT.

Are there Screen resistors? Same voltage on B+2 electrolyt and both Screens?
No screen resistors installed.
 

Lowerleftcoast

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Yea, I’m going to test this more aggressively and use some alligator clips to get more distance between the transformers.
More distance may be good.

Sometimes it is just the little thing that counts. A slight twist or 5mm movement to the front or back. Before you rip it all apart...

Pull the 6V6. Loosen the mounting bolts enough to move the transformers. Plug some headphones into the speaker jack (or just use the speaker). Turn on the amp and listen as you move the PT and OT.
 

filthytone

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More distance may be good.

Sometimes it is just the little thing that counts. A slight twist or 5mm movement to the front or back. Before you rip it all apart...

Pull the 6V6. Loosen the mounting bolts enough to move the transformers. Plug some headphones into the speaker jack (or just use the speaker). Turn on the amp and listen as you move the PT and OT.
Well, I did try early on to do some smaller adjustments (based on how much lead length I had). So at this point I don't mind going big or going home.
 

filthytone

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Well, I did try early on to do some smaller adjustments (based on how much lead length I had). So at this point I don't mind going big or going home.
OK, I literally pulled the OT out and put it beyond the chassis to the other side and it's still making this sound. There's no way it has anything to do with proximity. I decided to listen to what it sounded like with the OT completely disconnected and here's what I get:

 

dankilling

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OK, I literally pulled the OT out and put it beyond the chassis to the other side and it's still making this sound. There's no way it has anything to do with proximity. I decided to listen to what it sounded like with the OT completely disconnected and here's what I get:

Did you ever snug the PT bolts? Not the ones attaching it to the chassis, but the ones holding the laminations together.
 

filthytone

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OT primary voltage losses 37V and 24V seem way too high! If first tube bias current is 30mA it makes that primary half resistance 1200 ohms when they usually are 150...200 ohms each half for typical Deluxe OT.

Are there Screen resistors? Same voltage on B+2 electrolyt and both Screens?

Did you ever snug the PT bolts? Not the ones attaching it to the chassis, but the ones holding the laminations together.
Yes. I'm at risk of over-tightening at this point and stripping it tbh.
 

dankilling

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What kind of PT is it? I’m starting to think there is something going on internally on it with all you’ve done to track this down.
 

filthytone

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dankilling

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This is a Mojotone kit. It's this guy https://www.mojotone.com/Tweed-Deluxe-Power-Transformer_2 . And yeah, I've been avoiding thinking "oh hey just buy a different PT to test", but I really don't know what else to try considering everything I've done so far.
Id contact Mojotone, and point them at this thread. They have been responsive for me when I’ve had some issues in the past. Maybe they would be willing to lend a hand here?
 

filthytone

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Id contact Mojotone, and point them at this thread. They have been responsive for me when I’ve had some issues in the past. Maybe they would be willing to lend a hand here?
Yea, I contacted early on and got a couple things to check. I thought honestly this was pretty normal, but the more I got into it, the more I started realizing it can be a lot quieter, especially since it really doesn't seem to be an issue with grounding or wire layout, etc. The 120Hz points over to the power supply from everything I've read (still learning, so maybe I'm wrong). I might as well hit them up again and see if they can provide insight. I already have 2 new 6V6 tubes arriving tomorrow , so I might just buy a completely different PT as a test and see if that matters at all. I don't WANT to spend money, but this was supposed to be a fun side project and experiment, so let the experimenting continue I suppose!
 

ElPositivo

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Perhaps you could pull the transformers from your princeton and use those in the 5E3 to test what that sounds like. That won’t cost money but it will cost some time and effort.

These issues can be hard to track down.
 

filthytone

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OK, so I got a new power transformer just to be certain, but not a huge difference. With nothing plugged in and knobs all at 0, here's what I recorded with my iphone. Is this pretty much expected dB's for that frequency or can I keep digging? I've done so many things at this point, but can't get it quieter than this

IMG_0544.PNG
 

filthytone

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Wow. So I got a new output transformer and .... BOOM, problem solved. I can't believe somehow I had a bad output transformer, but it's true. Now this thing is quiet like it should be. Thank you everyone
 

filthytone

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OH. MY. GOD. So I decided to check something else because it was REALLY bugging me. I measured resistance in Ohms from Red to Blue and Red to Brown on the Mojotone output transformer. What I found was one of them was 300ish, the other was 600ish. So then I got to thinking .. did they swap a wire insulation color when building this ... So then I checked Blue to Red and Blue to Brown, and they are both close to 300 (a little under and a little above). So on the 5Y3, instead of connecting the middle red wire, I connected the blue. Quiet. The amp is now not humming like before. I can't believe I didn't test this, since I assumed that blue and brown would be the only ones that would make weird sounds if swapped.

I feel really dumb. But now this thing is dead quiet (without needing the new output transformer) and plays great. I really hope what I did here to fix this doesn't cause any OTHER issues I'm not thinking of, but holy crap.
 

filthytone

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OT primary voltage losses 37V and 24V seem way too high! If first tube bias current is 30mA it makes that primary half resistance 1200 ohms when they usually are 150...200 ohms each half for typical Deluxe OT.

Are there Screen resistors? Same voltage on B+2 electrolyt and both Screens?
You were 100% right all along. I'm still learning, and this was right in my face the whole time... 2 of the leads on the OT were swapped (wrong color insulation). The resistance was completely off. I swapped them and now everything is perfect. THANK YOU
 




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