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PostPosted: Thu Mar 19, 2020 1:59 pm 
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Here's another thought. The (3) 470k resistors in a row near the center left of the board and the ground buss. Consider reflowing their solder joints to the turrets, some of wiring leads look like they're just resting on the turrets. Good grounding and good connections are a must. Just spitballing again. Maybe this one will stick, too. :hmmm:

PS The volume and tone pot wiring did look kinda wonky, I noticed you were thinking about repositioning the components. But it's working now

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PostPosted: Fri Mar 20, 2020 3:05 am 
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Glad you got the tone control working. In the pictures it's hard to see that capacitor shorting to something it shouldn't touch, but things were pretty crowded in that area.

Good that you got the voltage to V3 up a bit. 20% down isn't too bad. It won't hurt the amp to run that way. 10 or 15% is better, though.

Yes, check those turrets on the cathode side. The connections to the 22k resistor look a bit suspect in the photo. Make sure all the connections on the ground bus are good while you're at it. A few of them towards the right side of the board ook a bit suspect, too, but it might just be the lighting and camera angle.


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PostPosted: Sun Mar 22, 2020 2:55 am 
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Thanks guys! All of my lead connections to the board are bend and inserted into the turrets and then soldered. Haven't had a chance to fiddle with the amp the last couple days but now I have some time to fiddle with it again and see if I can strengthen some connections any more than they are.
Quick question, Is it normal when you meter voltages on the V3 pins 2 and 7 (grid resistor connections, right?) that the amp/speaker hums really loud?


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PostPosted: Sun Mar 22, 2020 2:11 pm 
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Yes, it's normal to hear hum when probing the grids. It's a very sensitive area.


Last edited by mitch m on Sun Mar 22, 2020 2:16 pm, edited 1 time in total.

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PostPosted: Sun Mar 22, 2020 2:14 pm 
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Yes, it's normal to hear hum when probing the grids. It's a very sensitive area.


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PostPosted: Sun Mar 22, 2020 3:15 pm 
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Cuberdude, just to clarify, I was pointing out where the ground wire(buss) sits on top of the turrets and the jumper wire that connects the three 470k resistors in a parallel row near the center and suggesting reflowing /adding solder to them where they seem to sit on top of the turrets to make a good electromechanical connection. Again just a thought. Because I've made enough bad/cold solder connections with eyelets and I've heard turrets are a bit more finicky. Hank S. Here is a good article in Resources viewtopic.php?f=12&t=1261

PS Hope I don't offend, but don't know your level of expertise

Edit: I meant intermetallic bond, not electromechanical.

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PostPosted: Mon Mar 23, 2020 3:19 am 
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Thanks Hankules, no problem, you're fine haha. I've kind of been learning those things along the way for this project. I've soldered many times before but this is my first time with turrets. I've reflowed a few of those places now. I need to probably upload a couple new updated pics now.


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PostPosted: Mon Mar 23, 2020 1:42 pm 
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If the Plexi is your first tube build, it's pretty darn good. Some first builds don't work at all, like the my first Tramp build viewtopic.php?f=16&t=5938 , I futzed a jumper and it took awhile (a loonnggg while) to figure it out.

Yes, post some new pics, front and back angles are good. Also curious to see the revised volume/tone control area.

Any progress on V3 voltages? Hope you get it sorted out. :thumbsup:

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PostPosted: Mon Mar 23, 2020 8:13 pm 
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Here's a couple of newer pictures after some reflowing and the tone knob fix.
The amp works now and sounds great. The only thing is the voltage is pretty low on the V3 grid resistor area and I'm not sure why. I'm still pretty happy now though because this seems like a minor problem.


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File comment: Fixed the tone knob. Must have been a problem with the red heatshrink. I reflowed the pot connections and rotated the heatshrink and now it works.
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PostPosted: Tue Mar 24, 2020 4:05 am 
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The pictures look good. Glad you got it working. Don't worry too much about the low voltage on V3. Grid voltage is hard to measure in a circuit like that and the actual value can vary quite a bit. The main thing is it sounds good!

Have fun playing it!


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PostPosted: Wed Mar 25, 2020 4:08 pm 
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Do you have same voltage issues with 6v6 in use?

And I also noticed that that pin 8 on el84 is being used as a tie point . Which could be a no no with certain manufactures . Pin 1 for sure is a no no . But from this forum pin 8 is a Nono with JJs

https://el34world.com/Forum/index.php?topic=18789.

Found the data sheet for jjs pin 8 is ic

Finding dats sheets for othe manufactures of new tubes seems to be a pain as google gets more and more polluted with stuff for sale


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PostPosted: Wed Mar 25, 2020 4:45 pm 
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JJ. https://www.jj-electronic.com/images/st ... f/el84.pdf


Eh. https://shop.ehx.com/catalog/addimages/el84eh.pdf


As for the new sensor tubes eh has not provided much info


https://shop.ehx.com/vacuum-tube-specifications/


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PostPosted: Wed Mar 25, 2020 5:16 pm 
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Thanks for that information. I didn't know pins 1, 6, and 8 on EL84s aren't always free.

I see all the Trinity V6 layouts use pin 8 on their EL84s as a tie point for the grid resistors. The layouts for the other Trinity 18-watt amps and the TC-15 are OK. Sounds like it would be a good idea to install terminal strips and get the connections from the board to the 8k2 resistors off the tube socket. That way it wouldn't matter what brand of EL84 is used.

Or at least have a look at the EL84s currently installed and see if pin 8 is connected to anything inside the glass.


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PostPosted: Wed Mar 25, 2020 8:22 pm 
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Hmm. Interesting. Yeah, I'm pretty sure 6V6 and EL84 have the same voltage issue on V3. Thanks for the tips on EL84 socket wiring. I'm actually using JJ tubes as well...
So you're proposing to detach the 8k2 resistors and affix them to pin 2 and ground?


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PostPosted: Thu Mar 26, 2020 12:40 am 
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m


Last edited by sazafraz on Fri Mar 27, 2020 7:33 am, edited 1 time in total.

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PostPosted: Thu Mar 26, 2020 1:18 am 
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Look at your EL84s and see if pin 8 is connected to anything. It would be good to do the mod but it probably won't change anything at V3. It could make the amp less noisy, though.


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PostPosted: Fri Mar 27, 2020 12:01 am 
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