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Hi everyone,

I built a Telecaster copy last year from scratch, really happy with how it turned out and decided it needed an amp. Settled on the Tramp and just got it up and running but have a few questions and could use some feedback on measured voltages. I'm a true beginning guitar player but have a good friend who is pretty darn good. Tramp is getting rave reviews from him! Next step will be to build a cab head and matching 1x12 cab. I have a wood shop and am looking forward to making something nice out of fancy mahogany for the Tramp.

Here's my guitar:


And the innards of my Tramp build:



Had a few issues but by following the guide, spending quality time with the schematics, reviewing pretty much all of the Tramp forum posts and taking the time to not kill myself I got her done. She's hooked up to a 12" Celestion Gold 8 ohm speaker.

Still have a few potential issues though, highlighted in Red:

1. I added a second switch for the Load Switch EL34 option. I used the exact same Carling switch Trinity provides for the Bias switch. Upon testing with the 12AX7/6V6S JJ tubes Trinity provided with my friend playing a Strat at pretty high volume settings I noticed a couple of flashes. Settings were for the 6V6S but were got some arcing on the Load Switch contacts. Lowered the volumes immediately and it stopped. Anyone else seen this? Should I be using a higher amperage switch for the Load? Also thinking about insulating the solder contacts if the switch is capable of supporting the current. My solder joints look ok, nothing excessive reducing separation.

2. Voltage Checks:

I'll list my measurements for 6V6S, but not yet for the 6L6GC and EL34 power tubes. You'll see my question on these tubes below. All are JJ as is the 12AX7.

JJ AX127/6V6S

AC Main 120.5 VAC
Power xfmr primary in is 646 VAC target is 630 VAC, is this ok?
Heater is 6.8 VAC target is 6.3 VAC, is this too high?
1st cap is 437VDC, target is >400VDC
B+ set to 400 VDC with VRM
B+2 is 397 VDC target 397 VDC
B+3 is 334 VDC target 327VDC or is target 340 VDC per the schematics?

V1 12AX7
Pin 1 191 VDC target 203 VDC
Pin 3 1.7VDC target 1.7 VDC
Pin 6 193 VDC target 191 VDC
Pin 8 1.6 VDC not exactly sure of target, what is on vs. off on the Tramp Voltage Chart?

V2 6V6S
Pin 3 396 VDC target is 398 VDC
Pin 4 395 VDC target is 395 VDC
Pin 8 28.7 VDC target is 29.7 VDC

I have the 6L6GC and EL34 measurements as well but before I jump into my questions just need to verify that you cannot get B+ to 400 VDC using the VRM. Hopefully that is correct (I can get 387 VDC with VRM set at max, same for both tubes). Should I be using a different VRM output to measure performance on these tubes?

Good news is that the Tramp rocks! Nothing is melting, no smoke or crazy heat (Those 5W bias resistors do get pretty darn hot with things turned up!). I haven't taken a heat measurement yet but just remembered by DMM apparently can measure temp.

Thanks up front for your feedback. This was a lot of fun!

Cheers, Keith

Hi, Keef (after all, you are playing a Tele ). Nice looking build and nice looking guitar. but let's get to your questions.

1) Yes, some one has mentioned that problem in a past Tramp post. However, Coco says the small red switch should handle it. You say there's good spacing between the terminals, but you might pull the switch and make sure. Check posts about DPDT Switches in the forum. Side note, in the Tone Tweaking section, Coco suggests replacing the 560 ohm with a 1K ohm for EL34, KT66 and KT88. Sounds verrry nice.

2) Per build guide, with no tubes, you should be getting 630 VAC OR MORE at B+ (two red wires). With tubes installed, you should adjust the VRM (mine went above 400 VAC, 415- 425) so that you are reading 400 VAC at B+ and proceed to measure the voltages. Most everything I've seen in the forum says +/- 10% on voltages is OK, my heaters were on the plus end @ 7.0 VAC (6.3+0.7). Re pin 8 reading, I took it to mean OFF=the connection on the board and ON= directly on pin 8.

That's about all I can offer, and hopefully some one with more experience can verify my info, but from what you say my only concern would be the arcing at the Load Switch. YMMV

_________________
"The only problem with being retired is you never get a day off"

Thanks for the feedback!

Switch looks good, solder joints are not bulbous, have about as much separation as I can get between the contacts. I might just get creative with some shrink wrap or liquid insulation on the middle contacts. The head might look cool with a Tesla Coil on the outside but probably not desirable on the inside!

V1 stays pretty cool, literally not too hot to touch after being powered up for quite some time. If I understand correctly getting the voltage to 6.3 VAC is a longevity issue. Not sure if 0.5 VAC is going to make a huge difference.

Cheers

Hi Keith,
I did have this exact same problem with the arcing. I think there may have been one other report of this on the forum (or maybe through a PM to me..can't remember).

Here is the thread related to my issue. I've had no problems since installing the new heavy duty switch.
http://www.trinityamps.com/phpbb/viewtopic.php?f=16&t=4830&p=33352&hilit=arcing#p33352

Bruce

Thanks Bruce, yep, exact same issue, I can see some black marks at the base of the lugs on the V2 side of the switch. Switch still works fine, only saw a couple of flashes before I shut it down. Will try insulating the lugs, that should eliminate the issue unless I've got a short somewhere. Appreciate the quick feedback and for doing the legwork for me.

Cheers, Keith

This is a low current, application and again, the switch should be fine. We use both terminals of the switch to handle the current as a safety precaution.
We have two on build right now so will test them both.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Thanks Stephen, I'm using both lugs per your recommendation. Saw the arcing with 6V6S and pretty much had the Tramp maxed out on both volumes and power level was almost at max. In 'tude mode as well.

Cheers, Keith

Will test again here this week or next. This application should be fine. Both voltage and current are within switch spec.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

When I built my Tramp I used the 10A Carling switch (2GL73-50) that Pharmrock suggested, but would prefer on the next Tramp I build to use the smaller Carling 5A mini as the 10A version is pretty bulky. Had to run some wires farther than I wanted to from OT primaries (amp is still DEAD quiet, even so)! I wonder if it were mounted with the switch body as far away from the interior of the chassis and/or insulating washers were used, perhaps that would alleviate the arcing issue? Just a thought.

_________________
"The only problem with being retired is you never get a day off"

Arcing from body to chassis or between contacts?

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

I haven't had the same problem because I used heavier switch in my 1st Tramp. Those who have used the Carling mini switch mentioned arcing between the lugs AND possibly the chassis at high power settings. My suggestion was to offer a possible cause to investigate. Or it maybe it's some other cause. Was just speculating in previous post.

_________________
"The only problem with being retired is you never get a day off"

Haven't seen that in the two new builds we have here. Maybe we just typically keep all the bare wires far apart. There's no reason the switch can't handle it.
Will test again tomorrow.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Kieth,

Here is my post of the same problem you and a few others have had.
As per Stephen, & a couple other recommendations, I have made some adjustments to my wiring on the switch.

viewtopic.php?f=16&t=6267&start=20

Mine has been working fine ever since.


Scott