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PostPosted: Wed Oct 13, 2021 7:35 pm 
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Hi Everybody,

Did the Tramp build and followed all procedures. Now in the initial startup (no tubes, everything set to low/off). Light turns on and no shorts. However, the voltages seem lower than expected - specifically at the first 50uf capacitor, I get 88 instead of 400 DC (between wire and ground). I seem to get between about 84 and 87 DC (to ground) at many of the points that should be higher (should be 340, 203/191).

Any initial thoughts on what could be causing this?

Dave


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PostPosted: Fri Oct 15, 2021 6:40 pm 
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Ok - I think I have everything working now. Loaded the tubes, speaker and tested it with a guitar. EVerything appears to work - but there is a whistle/squeel when turning up the tude dial to high. I'll start troubleshooting that now...

Dave


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PostPosted: Sun Oct 17, 2021 6:26 am 
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As per the suggestion in the manual - I'm going to put a Mallory Capacitor "between grid pin 2 to the ground lug of the terminal strip.". Does anyone know if polarity/direction matters and, if so, how I can tell which is which on the cap?


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PostPosted: Tue Oct 19, 2021 11:21 pm 
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how to tell which side is outer foil:
viewtopic.php?f=14&t=3316

which end to connect to ground:
https://www.aikenamps.com/index.php/whe ... capacitors


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PostPosted: Wed Oct 20, 2021 4:19 pm 
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Thanks - installed a mallory cap both ways to confirm - the squeal was eliminated in either configuration. So amp build complete!


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PostPosted: Thu Oct 21, 2021 8:48 am 
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Awesome! I did this same mod to my Tramp and it took care of the issue as well. Easy fix.


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PostPosted: Thu Dec 23, 2021 4:53 pm 
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No tubes installed yet.
I'm getting 87 volts at capacitor 1, 450 at capacitor 2, nothing at 3, and 87 at capacitor 4&5.

This seems way off.


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PostPosted: Thu Dec 23, 2021 4:53 pm 
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No tubes installed yet.
I'm getting 87 volts at capacitor 1, 450 at capacitor 2, nothing at 3, and 87 at capacitor 4&5.

This seems way off.


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PostPosted: Thu Dec 23, 2021 4:54 pm 
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No tubes installed yet.
I'm getting 87 volts at capacitor 1, 450 at capacitor 2, nothing at 3, and 87 at capacitor 4&5.

This seems way off.


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PostPosted: Mon Dec 27, 2021 1:29 pm 
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Location: Shawnee, OK
Voltages usually are different w/o tubes installed. Testing the voltages w/o tubes is mainly to see if you have power at B+ (1st 50uF, 450V cap). After tubes are installed, use VRM to adjust B+ to 400VDC (if higher than 400VDC w/o tubes) and take your readings per chart on pg. 45, ver. 21.9.. Don't know for sure if this is what you were asking or if it helps. It's been a while since last build. Hank S.

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PostPosted: Mon Dec 27, 2021 2:01 pm 
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Hank,
I learned that voltage changes when tubes are installed by measuring with the tubes! My voltage readings were fine and after two shorts from leads extending below the circuit board and one pair of swapped leads……it is working PERFECTLY. Thanks man


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PostPosted: Mon Dec 27, 2021 11:43 pm 
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Glad you got it sorted out, how you liking it?

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PostPosted: Tue Dec 28, 2021 9:05 am 
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I’m really liking it. But, it’s going to take some time to figure out all the combinations to get different tones. I’ve been playing around with some vintage 12AX7 tubes to see which sounds “best” (all are good just different).

I’m also going to try a 1954 vintage EL34 later today. The tubes came from my Dad’s garage.

-Brian


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PostPosted: Thu Dec 30, 2021 6:33 pm 
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Disclaimer: I'm not a player. Though, having heard a friend playing the Tramp through a Texas Heat and Cannabis Rex twin speaker cab I really like the EL34 tone. Your thoughts on the EL34 are solicited. PS What was the solution to your voltage problem? Just installing the tubes for your voltage measurements?

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PostPosted: Thu Dec 30, 2021 11:01 pm 
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Voltage issue was “rectified” by installing tubes. EL34 has a slightly different tone and definitely louder. Hard to do a side by side and I’m still fiddling around. Bass and treble controls don’t make much of a difference.


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