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Hi,

Finally able to build the Tramp I bought just over 2 years ago. The build doc is v1.99 and the wiring diagram is up to rev. 16.

The build seemed to go well but I am not getting any sound. I checked the forum and the typical problem seems to be the shielded cable/shield connections.

I initially did miss that but corrected (I thought) it after searching the forum but still no sound.

I seem to have power and the tubes are aglow but it's still no go!

I am including some photos and would appreciate any help.

Edit note: I removed the photos since I'm reposting due to build issues.

Michael

I feel your pain, brother! I had the same problem when I first fired mine up. Turned out I had the shielded cable from the volume (gain) pot to the wrong spot at the pre-amp side. Quick fix once I spotted it.

One thing I noticed in your first picture is that the shielded cable you have going from the volume (gain), the shield might be touching where it is soldered where the 330k resistor is. This part is slightly tricky - you want the shield grounded at one end only, i.e.: on the volume pot. On the other end, you just want the lead sticking out and the shield needs to be insulated so that it doesn't touch anything. I used a small piece of heat-shrink tubing. Not sure if that would cause the issue of no sound though.....

When you turn the VRM all the way up, the master volume all the way up and the gain all the way up, do you hear any sort of noise / hum, etc. coming from the speaker? Anything to suggest it could be on the signal end rather than at the output end?

There looks to be 2 missing resistors between the two 450V 50uf capacitors....
Unless you hid them on the bottom of the board....

Andrew

Look at me trying to be the 'expert' here.... I'm not. I've only built one amp, just finished it up. I've looked over the rest of the pictures and I think my conclusion above may have some merit. I'd suspect your signal in might be getting grounded out via the shielding. That's probably where I'd start. I found that heat-shrink tubing came in very handy to ensure the shield is well insulated. I used it for this purpose at both ends of the shielded wire.

You may also benefit from re-flowing some of the solders, in particularly on your board to ensure good connections. I've read in other posts that this can help.

Those resistors don't necessarily need to be there. Purpose of those resistors (if I can explain this properly) is to basically drain the residual current out of the capacitors upon shutting down the amp. They are very useful for not electrocuting yourself, but not necessary to get sound to come out of the speaker.

The input jack could also be shorted to ground too... I do not see any insulation separating the shield at the cliff jack...

are you getting any sound? hiss pops?

Did you check the voltages on the tubes to see if they are looking correct?

Thank for the feedback guys.

Yes, you were right about the shield at the 330k resistor, so that's been fixed, including heat-shrink tube.

Turned up master volume, VRM, & others with no sound whatsoever.

The 2X220k resistors are on the bottom.

I'll redo the shielded cable for the cliff jack, but I don't know what you mean by "I do not see any insulation separating the shield at the cliff jack...".

Do you have a photo maybe?

I appreciate the help on this.

Michael

Michael - he is suggesting putting some heat shrink over the shield at the input jack, just to make sure it isn't touching something else other than the ground lug. For example, if the shield is touching the the opposite lug as well, it will ground out the signal.

What are your voltages like? First check!

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

Some of the solder joints on the board look a bit blobby. The solder should flow smoothly into the eyelet if the joint is good.

Like Stephen said, check all the voltages at the board and at the tube pins. That's the biggest clue to the health of the amp, especially if there is no sound at all, not even hum or hiss.

Michael, how are those voltages looking? The book explains how / where to check voltages as well as the desired reading.

I redid the cliff jack shielded cable so it should be good but ...

the voltage on the first 50 uf cap is 23.9, not anywhere close to 400.

Is it still possible I'm grounded out?

Also I'm not really literate with measuring voltages so getting up to speed on that. The good thing about a problem is forcing you to learn if you want it fixed. Andrew, what book are you referring too? You mean the build doc?

[quote="mmcginn"
Also I'm not really literate with measuring voltages so getting up to speed on that. The good thing about a problem is forcing you to learn if you want it fixed. Andrew, what book are you referring too? You mean the build doc?[/quote]

I really wasn't all that literate either before I did this build, but caught on quickly as I went. The book is the build instructions - I put mine into a binder, kind of looks like a book.

Try this for the voltages:

1) Set your meter AC. Measure across the rectifier pins. This is where the twisted red wires from the transformer attach to the board, just above and to the right of the MOSFET - where the diodes are. Make sure your meter can handle 600+ volts. Again, make sure it is set to AC. Put the black probe on one of the eyelets, the red probe on the other eyelet (amp has to be on of course). You should have close to 630VAC here. If you put the red probe on one of these eyelets and the black probe to ground, you should have in the neighbourhood of 300-315VAC.

2) Set your meter to DC. Now measure across the 50uF capacitors. With the VRM all the way up you should have 400V. With the VRM all the way down you will have substantially less. If you have alligator clips on your meter (with the amp off) you can clip the black lead to the negative side and the red lead to the positive side. Then turn the amp on, to idle. Voltage should be fairly low. Slowly turn up the VRM and you can actually watch the voltage rise on your meter

3) Keep the meter set to DC. Measure at the pre-amp side. Pin 6 should have 191 volts, pin 1 should have 203 volts (or close to those numbers). Hold your black probe to the pre-amp ground and the red probe to pin 1 or pin 6 depending on which you are testing

You can check your heater voltages (meter set to AC) at pins 7 & 2 on the power tube side and pins 4 & 9 on the pre-amp side. If I remember correctly, mine were around 6.7V. The manual says they are to be 6.3V.

Actually, then very first thing you should do is check the main voltage coming into the amp. Hold your black lead to ground and the red lead where the wire connects to the fuse holder (or on the 'power' pot where the wire attaches that comes from the fuse holder).

Anyway, give that a go and see what you come up with. Be careful... you don't want to short anything out or electrocute yourself. Make sure you are touching only the circuit you are testing with your probe. If you are uncomfortable with this, use leads on your meter that have alligator clips instead of probes. This way you can turn off power to the amp, clip your leads where you are testing then turn the amp on and your hands are free.

Hope this helps. I am not trying to be an expert with this, just passing along some stuff I learned while building my amp.

Andrew, your advice is pretty expert for someone who has just built his first amp. By the way, your cabinet looks fantastic!

Michael, do you have 400 volts DC on the + side of the second 50uF capacitor (C13)? Does the voltage at the + side of first 50uF capacitor (C12) vary with the VRM control?

If not check the wiring and the solder connections to the mosfet and and the other components that connect to it. Do you have the jumpers shown in dotted red lines on the layout drawing installed on the bottom of the board? Especially the ones running from the 100R resistor to the drain of the mosfet and the one running from the 5R resistor to C12.

I'm not a Tramp expert, either, as I have never built one. I'm just going by the drawings in the Resource section here on the forum. I've built lots of other amps, though, including a couple of Trinity kits.

Good luck,
Mitch

333VAC for both.

315VAC for both.

Cap 1 VRM idle: 25DCV
Cap 1 VRM max: 285DCV
Cap 2 VRM idle: 463DCV
Cap 2 VRM max: 460DCV

Both pins 288

Pin 7&2: 3.6V
Pin 4&9: 3.6V

.167V

I see there is a little bit of fixin to do!

Voltages in response above. Prior to this voltage test I did some additional soldering to firm up some connections. The jumpers and other resistors are on the bottom. I did re-check many times but there is always room for error.
Appreciate the help.

That sort of taps out my knowledge. If you are getting 315V from each rectifier pin to ground, you must have 630 across the pins.

When you check your main voltage, be sure to switch the meter back to AC.

If you measured your heater voltages across the pins (i.e.: not each pin to ground) then those voltages are low.

Voltages on the pre-amp tube look high.... try measuring those at the board (where the lead from those pins connect to the board) rather than on the tube socket. The colour schematic that came with the kit shows what the voltages should be (the numbers circled).

Looks like the VRM is varying the B+, but if you only get 285VDC with the pot up full there is still a problem somewhere in the B+ chain. According to the schematic and what Andrew said there should be around 400VDC at C12 with the VRM set to maximum.

Try measuring the voltages along the B+ chain and see where they start getting low. Use the schematic and the layout drawing to help you trace the path.

The B+ measures good at the diodes and C13. From there it goes to R23, the mosfet, R20 and C12.
It's low by the time it gets to C12, so check the wiring and connections through this area. Also check the connections to the VRM pot, R21, R22 and Z1.

From there the B+ goes to the output transformer so you should read about 400VDC there and at the anode of V2 (Pin3). B+ goes to R17 and R10 next so it gets lower until it's about 340 VDC by the time if feeds the anode resistors of V1 (R4 and R9).

At the anodes of V1 it should read around 191VDC at Pin 1 and 203VDC at Pin 6. You get 288VDC on both which is the full value of your B+. That says V1 isn't drawing any current on either triode.

The anode connections seem to be good but there could be a problem with the cathodes. Since it affects both triodes, check to make sure all the "Preamp grounds" on the board are connected properly.

This is assuming you have a good 12AX7 installed as V1. A bad tube, or no tube at all, would also cause the voltages to read high at Pins 1 and 6 since no anode current is being drawn

Good luck
Mitch

VRM max VRM idle
Baseline Actual Actual
400 - 304 - 0
29 - 0 - 0
340 - 297 - 25
191 - 297 - 24
203 - 297 - 24

Measurements are with no tubes so I'll put the tubes back in and re-measure. I have 2 sets just in case.

Many thanks Mitch