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Just starting to dig into a TRIWATT build. Populated the chassis, the manual says 6 terminal strips, I can only see 5 on the wiring diagram. Seems perhaps one was removed from the other side of V1 in this design, revision 19? Any thoughts on input jack orientation? I've set Normal and Bright inputs horizontal and the Link input vertical because that seemed like it would be easier to wire Normal and Bright that way. Looking forward to the rest of the build.

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I had two terminal strips attached to the last tube socket. Now it was 6 years ago that I did my build so things might have changed. Hope the photo helps.[/img]

In retrospect would you have oriented the inputs differently?

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No. I pretty much stuck to exactly what was shown on the layout. My limited knowledge of electronics made me want to stay with the plan. There was some photos from Zaphod that helped a lot. Here's a shot of my result.

On to the next question

The manual says "Tightly twist the AC main leads (Black/Black) together," of the four Black leads, Black-Red, Black-Yellow, Black-Blue and Black, which should I be twisting?

From the PT diagram and the wiring diagram it looks like I should twist Black-Red with Black-Yellow and then Black-Blue with Black for 120V operation. Does that sound right?

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That's right. From what I have seen on the layout drawing, twist Black/Red and Black/Yellow together and run them to the power switch. Twist Black and Black/Blue together and run them to the neutral terminal on the IEC connector.

There's also a wire that runs from the fuse holder to the power switch. If you want, you can also twist that with the runs from the PT to the IEC connector and the PT to the power switch. Hiwatt ran these bundles through plastic tubing, but twisting is good, too.

Wire the input jacks however you find it easiest. I think the standard layout would be less cramped. It would be even easier to pre-wire the Normal and Bright jacks outside the chassis. One trick is to temporarily mount the jacks backwards so the terminals are on the outside of the chassis and the nuts are on the inside. That way they are in the proper position but you have a lot more room to work on them.

Just finished the heater wiring and ran into an inconsistency between the wiring diagram and the manual.

The wiring diagram shows Black to Pin 7, Red to Pin 2 of octal sockets then Black to pins 4,5 and Red to pin 9 on the 12AX7 sockets. This is how I wired them.

But the build manual has the 12AX7 socket pins reversed, it says Red to pins 4,5 and Black to pin 9 on the 12AX7 sockets instead.

Does this make a difference? If so, which was is best? I would hate to have to rewire these.

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Ran into another question. The manual says "Use Yellow and Blue etc. 20/18 Gauge, stranded, for power supply hook up - to transformers, rectifier, standby etc." However no stranded came in the kit (5 lengths of solid core, 1 length of shielded, 1 twisted pair solid for heaters), there's none listed on the parts print out either. I don't think there's enough length of cut-offs to connect the fuse holder around to the power switch. Am I missing something with what I've got or am I just missing some stranded?

There may be enough cut-off to use Green or Green/Yellow stranded, but I thought best practice was to keep Green for grounds.

What are the stranded specs? or a Digi-Key part number? Conductor Strand, Jacket (Insulation) Diameter, Jacket (Insulation) Thickness, all those wonderful Digi-Key filters make it a little daunting.

FWIW it looks like the wire on the PT is 16 AWG 26/30, and the wire on the OT is 18 AWG 16/30. So this should work?

18 AWG, Stranded, 16/30, PVC, 2.84mm Insulation Diameter, 0.81mm Insulation Thickness

http://www.digikey.ca/products/en/cables-wires/single-conductor-cables-hook-up-wire/474?k=&pkeyword=&pv77=2076&FV=1380005%2C1440042%2C1480004%2Cffe001da%2C6740045

Update, a little too much insulation on that stuff. It still works, but it's not as easy to set bends into as I'd like.

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Moving along here, populated the turret board, noticed I don't have a 2W for one of the resistors that calls for 2W, R43 (180K), though the circuit diagram has it at 1W. I assume since the circuit diagram says 1W this is going to be okay?

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Here's the board populated.

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Looking clean. onwards!!

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

Ready for final wiring check.

The only thing I know I messed up is I didn't leave enough length to swap the OT leads between the power tubes if I need to -- read that tip in the manual after I'd already wired them. Hopefully (knock-on-wood) it won't come into play.

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The heater question: as long as all the preamp tubes are wired the same way you are good. We will fix the inconsistency.
The stranded wire question: typically we try to use cut offs where we can. 18 ga stranded is fine and we are going to start including some in the wire packages for the kits going forward. Solid will work fine too.
The resistor question: 1W is fine as the voltage dropping resistor; standard now.

Your build looks good so far!

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

Thanks. Running into some confusion testing the transformers. I hadn't tested them before since it seemed like you needed the board populated to fully test them, so I moved on to that, when I had the board done and in, I forgot to go back before wiring the PT.

Anyhow, trying to test now as the manual instructs. I desoldered the PT hi voltage secondaries from the board (the diodes), both red wires (everything else is still soldered). The pilot lamp came on nice and bright, so I moved on to testing the secondary output, when I test the high voltage secondaries by attaching my meter between them I only get .3 VAC, where should I go from here? The OT is fully wired.

Only reading about 2.5 VAC at the pilot lamp.

I tested the resistance on the PT leads to the pilot lamp before and they were low to ground, but not 0.0, now they're both around .5 ohm to ground (which is probably my probe's resistance).

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confirm that you have 120 V at the primary leads

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

With the amp off, the pilot unplugged, when I plug in the power I get about 100 VAC then it falls slowly to about 90 VAC, over the course of 30 seconds or so. I'm getting that across the primary leads past the fuse with the amp on stand-by. I've got primary blue/black striped and black going to one side of the IEC and primary red/black striped and yellow/black striped going to the power switch.

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mains voltage dropping is very strange. i assume your house voltage is stable so might be a bad wire or fuse? still, can you measure the secondary AC and relate it to the mains voltage. You should still be getting high voltages off the secondary reds and closer to 6.3V on the heater/ pilot light

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

Solved. Fluke meter battery was low causing bad VAC readings. I suspected when I realized the only way the mains would drop as soon as I attached the meter is if the meter was causing it, or reading wrong. Phew. Swapped in another 9V and I'm reading 6.4 VAC on the pilot lamp and ~750 VAC or so on the secondary reds -- that's more like it!

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One of life's little mysteries - solved!!

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

Okay, next issue. Moving along. Everything checked out fine. Put the tubes in, attached a speaker, put the amp into stand-by. Trying to bias but I can pick up any meaningful readings between the red sockets and the black, even with my multimeter set on 300mV DC. The manual doesn't mention anything about the two bias test points, should they match?

The second, larger issue I've run into is that with tubes in and a speaker attached, if I take the amp out of stand-by I get a loud feedback tone, a sharp squeal coming from the speaker -- I mean shut the amp off immediately loud. Does this mean I've got to switch the OT primary leads I left too short?

Short video of the behaviour.

http://www.youtube.com/watch?v=lVn0lDOZGtQ

After some testing it seems like the output jack tip lead coming from the impedance selector is reading almost 0 ohms to ground -- or is that normal for the coil off state? The speaker sounds like voltage across it to me, but I don't have a dummy load to do much direct testing that way.

For completeness, tubes I've put in are all new, two match JJ 6V6S's, three EH 12AX7's and one JAN-Philips 12AT7WC.

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