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Been waiting for time to get this together...I'm on a medical leave, so I'm trying to take advantage of the time off by starting the Tramp. Just now going through the BOM & starting to mount stuff on the chassis - will post some pix as there is progress.

How's the build going? Weren't you going to put in an EL34 as well?

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

I'm afraid its going very slowly...kind of sucks not having a workspace, I have to find time to set up/put away around everything else going on. I've gotten most of the parts mounted & have started wiring, but haven't really had time to progress very much past when we spoke on the phone...

I'm baa-ack!

Sorry, it's been awhile - but I finally have a place & time to get back to work on my Tramp! I got rotated to the overnight shift, so I find myself with two nights a week with nothing to do, as my family lives on normal time. So, while the kids are sleeping I head down to my parents' place, where I have taken over an extra room for my bench. (An added benefit is that I can leave things sitting where they are & not have to put everything away, like in our apartment...)

So: pix!

On the bench: most hardware installed.



Was actually short one terminal strip, so I did the power transformer connections directly. I'm going to tie these off with a ziptie and anchor.



Last night I got as far as installing the output tranny. Connections TBD...


One from above:



I'm still thinking I'd like to set it up to switch between KT66 and EL34. There was something in the directions (don't have them in front of me right now...) about using one of the alternate taps (2.5?) on the OT for EL34. One thing I have yet to find, though, is how to tell which is which? Was that somewhere else in the docs? (I know, RTFM... I will look further this evening.)

Hey - Hooking up the OT to the impedance switch...I followed the directions:

yellow - pin1
green - pin2
orange - pin3

jumper from center lug of switch to + tip of output jacks
black lead to - sleeve of output jacks

I had checked the switch before connecting, and beeped each pin to the output lug according to switch position, and they were all discrete. Everything looks clean & clear - did a quick continuity check with my meter, but I get beeps across pins 1, 2, & 3 to both positive & negative jack connections, regardless of switch position. Is that normal? How does the switch work, if all leads are connecting anyway?

Something else that is confusing: looking at the picture on pp. 31, it appears that you have connected the center lug of the impedance switch to the - sleeve connection and the black OT lead to the + tip, although the directions AND the schematic state the opposite (I followed the latter).

The leads in the OT are not seperate, in fact, they are connected in the OT. that is why you get those readings.





In the OT, Black is Common and goes to the sleeve. I will check the document picture.

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

Thanks - I thought that the OT connections might cause that, but I did want to check with the experts before proceeding. I'm back on tonight, but will forge ahead next week.

Hey guys!

Need to catch up a little - over the past couple of weeks I've gotten the circuit board populated, and am now ready to mount the sucker & connect it to the chassis components. Pics:

Laid in my jumpers (photo from after component installation)



Board after installing components:



And with lead wires:



I'm in the middle of my work week now - probably Monday night -> Tuesday I'll get back to the bench & get her in the chassis. I also need to get on with my woodworking soon - need to cut out & route for the controls so I have somewhere to mount this baby! - and order a new 12" speaker...

Hi
Was there a carbon comp-brown resistor in the package? See the 220K brown resistor in the layout

The resistor isn't too visible in the picture, it's tucked under the large Cap, but it's there.

hmm...glad you asked me that. Checked last night, & i see that I actually didn't use the carbon comp resistor. Fixed!

Well, I finally got all the connections made. Powered up, no smoke - that's a good sign! - but...

I do have a few issues to sort out. Any advice is appreciated!

With no tubes installed, apply power. Leave VRM at idle and measure the DC voltage on the first 50 uf filter capacitor. It should be over 400 VDC.

Check!

Measure the AC voltage. Ensure the multimeter is set to AC. Measure across the rectifier pins where the transformer secondary was connected. It should read (630 VAC minimum).

Huh? I did not understand where this was, and could not find any specific reference to the rectifier pins or transformer secondary in the manual that shed light on this. Can somebody tell me specifically where to check this voltage?

Test the filament voltages and ensure they are on the correct pins for all tubes. 3.15 from each pin to ground or 6.3 across the heater wires on the tubes sockets.

Check! Pins 4,5, & 9 on the 12ax7, and pins 2 & 7 on the octal.

If everything is okay, power off the amp, install the 12AX7 and the 6V6 power tube and power on again.

Did this, but with the KT66 not a 6V6. I can probably dig one up if it really matters...but it lit up OK.

The preamp tube did not glow at all. Tube should be good, it had been used briefly before & was working. Any thoughts on what to check first?

Plug in a speaker, install the tubes and turn it back on again. Leave VRM at idle while tubes warm up. Ensure all settings are at Tweed, Thin. Then measure the DC voltage at the second 50 uf cap on the + terminal. As you turn the VRM, the voltage should rise. Test to see if it increases as the Level control is very slowly turned clockwise. If this doesn’t happen, turn off immediately and recheck the connections.

DC voltage at 50 uf cap was 450 volts no matter where the pot was. Connections seemed to check out. Bad pot, or...??

This is across the two black diodes where the Power transformer leads were soldered to the board. I would say, based on your DC voltts, it is OK.

If everything is okay, power off the amp, install the 12AX7 and the 6V6 power tube and power on again.



Needs 6.3 VAC across pin 4/5 and pin 9 to glow. Confirm heater voltages



Check your power ground connection from board to the terminal strip where the power transformer grounds are connected. Should be from filter caps -ve side to ground.

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

Thanks Stephen!

I believe I did did get 6.3 across pins 4/5 & 9. I will double-check that, and bring along an extra couple of tubes when I get back to the bench.

Rechecked voltages on the 9-pin - all OK, so I swapped the tube & it glows.

I also noticed that I had swapped the pin 1 & pin leads to the Power Level pot. Switched them back where they should have been & now I got some variation the 50 uf cap, although it was about 12 volts difference...

Oh, I also swapped the KT66 with a 6v6 for testing.

Moved on - all the other voltage points seemed to check out pretty close. I did notice that checking for 400v on the + side of the 50 uf cap tested pretty high at idle, about 425v, but if I left the meter connected the voltage dropped slowly, finally landing on 400v. (Is that normal or a problem?)

Audible check - nothing, except a slight buzz in the speaker. Constant (volume/tone controls do not affect it) but not very loud, and it modulates when the power level is turned. NO sound from input jack, though. I checked the first part of the path (shielded connections) and re-flowed one joint that might have been sketchy, but still no sound. Any advice on back-tracing the audio path?

First of all stick with the 6V6 while you're getting the amp on running, since that's a known reference tube. Also, like I recommended in another thread it might be a good idea to temporarily short out the VRM. We need to eliminate that from the equation and first get the main part of the amp working. Solder a shorting wire from the VRM end of 100 ohm resistor R23 to the + end of the second filter cap C12.

When you go through the amp measuring voltages at tube pins, you should hear the speaker click. Does that happen?

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Great tones come in small glass jars!

Done



No.

I'm getting 177 on pin 1 and 188 on pin 6 of the 12ax7. That seems kinda low on pin 1?

At the 750 ohm resistor (the 29 on the drawing) I get nada. Thought I had gotten a reading there yesterday, but maybe not...

AHA!

Found out that I'd missed the hookup wire from the - end of the 1st filter cap to the power ground! As soon as I ran this I was getting better readings and...AUDIO!

Pin 1 = 222-225v (too high?)
Pin 6 = 174v
Cathode = 26v

Not too bad, I hope?

All the controls seem to work - can't get the full appreciation of the tone using a raw speaker on the desk, but if this seems OK I'll be moving on to the cabinet next week.

On which tube? Pins 1 and 6 aren't connected inside a 6V6 or 6L6.

Yes, the speaker has to be inside a cab.

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Great tones come in small glass jars!