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Day 1. Arrived about 4pm. Got this much done, have not assembled chassis.


I had one 'oops nearly missed that one' connection, thus the slight mess at the top right by the .1u's.

Couple of questions:
1) The Sozo's are obviously marked for polarity. The small yellow .001's are not, I didn't bother trying to orient them other than putting them all the same way for 'neatness sake'. Same with the white .1u's. Should I be concerned?

2) The 2 flying leads I put in, purple wires at the top of the board - I see them as bridges (into the top of 22n, and into the top of 1n, when viewing the layout). Any reason they are done this way rather than just joining along the buss?

Never did figger out the trick to keeping component leads straight

Regarding polarity of the Mallory caps, I had similar questions which were answered in this post - viewtopic.php?f=14&t=3316.

kurtlives provided a link showing how to fairly easily determine the polarity of these unmarked caps.

If I understood correctly, the amp may be a little noisier with the unmarked caps in one direction vs the other, but I don't think you'd probably notice it to any extent in the Triwatt.

..Those short purple lead are not required. If you look at the docs in the resource section you'll see short green leads....These are actually the shielding from the shielded cable going to pots. Not sure but Stephen usually includes a diagram of how to prepare the ends of the cable to give you two connections.
Stew
Have a look.
viewtopic.php?f=2&t=1144

AHHHHhhhh OK I see it now. I'm sure it is laid out in the written instructions, I'm just mostly working off the layout at the stage I am at.

It would be nice if the layout had a key for colour coding the wires, like
-grey = shielded
-green = heaters (not saying that, just throwing out something)
-blue =
-purple =
-red =
and so forth.

The resistor on the board, left of the 2 50u caps, is 82K. My leftover resistor, after populating the rest of the board and checking what I have ahead on the offboard layout, is 92K. OK to use, or head for the electronics shop?

Assembling chassis. Have 6 tagboard strips, but only see spots for 5.
-between vol pots
-between pres & master
-by V1
-by V3
-under bias pot

Also haven't yet figured out which transformer goes in which position. Looks like PT on the right of the layout, OT left near the power tubes.

91k and 82k are very important. Make sure They go on the board.

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

91k and 82k are very important. Make sure They go on the board. Also, OT goes in the middle.

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

I wasn't suggesting I would skip a resistor.

I didn't get an 82K. I got a 92K instead. I have an empty spot for the 82K and an extra 92K resistor. I was asking if it was OK to use it in the spot labelled for 82K. If I have to go get one, what wattage rating do I need?

I don't read values by stripes, I measure them all with my meter. Twice, once sorting them and sticking them in a styrofoam block and secondly before I solder them in. That is not to say I may not have made a mistake, but I'm reasonably confident I didn't.

Today's progress:
finished board, but for the 1 resistor



In the picture above are 'leftover' components (above the board) that I didn't find a home for. Guess I'll start a 2nd amp Actually, the black grommets, are they for where the transformer wires come thru the chassis? The 2 extra ground points, I haven't got a clue.

Started on the chassis, have mostly everything mounted. Things like jacks and some switches are just finger tight, so I can take them out to work around them.

That resistor you have on the board is 82K not 91K. It's worth while learning the resistor colour code system, its easy to learn and is quicker than measuring. It also gives you another way to validate the resistors values. The colour code value will also tell you the nominal value which is good because the nominal value and actual value don't always match up. I also say this because I see you measured a 47R resistor and put it in the styrofoam block, there is no 47R resistor used in the Triwatt.

Anyways you'll need a 1/2W 91K carbon composition resistor. If you kit didn't come with one contact Trinity about it.

The grommets are indeed for the OT and PT holes where the leads go through. It's worth installing those now while your still in the early stages of building. You don't want those wires fraying or rubbing on the chassis.

The extra terminal strip is for the V1 socket check the layout.

I notice you didn't install the OD pot spacer, might want to look into that.

You might want to rotate your terminal strip near the presence pot/master volume pot 180 degrees by the way.

The extra ground terminals are for the power area. Look at the right hand side of the layout for these ground terminals. They should be #8 terminals. The preamp ground is #4 size btw.

Decided not to put on the tube shield bases?

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OK the one you say is 82K, 2 spots left of the empty hole for 82K, measures 90.9K - so naturally, I took that to be the 91K resistor called for there. The leftover resistor I have is 92K so close enough to the 91K you indicate I need - if the 82K that measures 90.9 is OK, then I'll just put the 92K in where 82K is called for. Not sure where you see 47R, it says 47K on the styrofoam block.

The grommets don't fit the holes, I emailed Stephen a picture showing there is no way. I'll use electricians tape or heatshrink tube around the wires going thru the chassis unless I figure out a more elegant home baked solution.

I figured out the extra terminal strip and ground terminals. I installed the terminal strip by the pres/master both ways, looking at zaphod's pic he has it the way I have it - there is enough clearance that it won't ground on the front of the chassis.

Tube shield bases I totally missed, good catch. The OD pot spacer, I still have it and know it should be on there, I just have to find the post showing 'how' - I've read it before, so I know it's here somewhere.

Thanks for your input!!!

By the by, I figured out AFTER day 1 working on the board, that the leads should go in the top of the turrets, and that makes it easier to have straight leads. I wrapped all the leads around the top of the terminals - like, where you put the buss wire - so I just finished the rest of the board that way. Live and learn

Hmm ok
82K should be grey, red, orange.
91K should be white, brown, orange.

If 82K measures 90.9K then it is out of spec. The silver band at the end of the resistor indicates 20% tolerance. That is why your resistor is measuring a bit high.


I mistyped you have a 48R on your styrofoam block (which isn't used in the Triwatt). To my eyes it looks like 100R (which is indeed in the Triwatt). Your multimeter may have a bad/dying battery. Might be worth replacing.

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Ah. Thats 98R not 48. So, you are correct it is a 100R. Meter battery is fresh

I'll just go buy an 82K 1w tomorrow, no big deal as I have some other things to pick up at the electronics shop.

Question re: Transformer orientation. The guide says rotate one 90 degrees from the other. But then later, the finished chassis pic in the guide has them oriented the same way, and the chassis holes are drilled such that they can't be rotated.

I know there are any number of good completed builds...but I'm wondering how worthwhile it may or may not be to drill holes to turn (probably the OT) 90 degrees. I have a drill press, so it's probably not a lot of work. I'll just have to double check spacing of everything inside before I proceed. Opinions?

No definatly don't do that.

Looking at your OT you have it 180 degrees backwards though. The OT secondary wires (green, yellow, orange, black) should come out of the holes in the chassis and go right to the impedance selector. The primary wires (red, blue, brown) should come out of the hole and go right to the power tubes.

Look at the third pic
viewtopic.php?f=14&t=3135

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kurtlives is correct. Dont do that Follow the layout and stick to it as close as you can. If you dont, there will be consequences - squeal, hum, distortion etc.

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

I would suggest wiring up the input jacks before you mount them. I didn't do this on another build I did and regretted it. On my triwatt I wired pots, etc. before mounting them and felt much better. Also ran some of the leads before I put the board on and it made for not bending stuff easier.

Rotated OT 180, thanks again.

The holes where the wires come thru the chassis are 3/8", too small for the supplied grommets, which appear to be 1/2". I bought some rubber ones at Home Depot but they won't work either. I think the supplied grommets are right and the holes were punched too small, but I haven't heard back from Stephen yet. So, as a temp solution, I have braided the wires and then DOUBLE wrapped them in electricians tape - I recognize this is not ample protection long term, I'm still puzzling out what to do. In fact, the holes are so small I had to unbraid the 3 green wires off the PT as they wouldn't fit thru the hole braided.

Added the tube shields. Added washers to where the transformers mount, as I wanted to go screw inside/nut outside....way too hard to try and get a screwdriver at the screws if they were on the transformer side.


Below, yes I will trim back the tape wrapping on the PT wires. And, yes the red wires are braided inside the tape.



Tyler, yes things like pots and jacks are just finger tight. I have built enough pedals that I know to pre-wire as much as possible before locking down in place.

Hmm, We had some Triwatt chassis that were 3/8. Normally these get reamed to 1/2", but we missed yours. We'll fix it for you.

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

Stephen gave me the OK to put the chassis into my drill press. Aluminum is easy to drill and doesn't tear (at least, I've drilled probably 100 pedal fx enclosures which are aluminum and never torn one), but does spray aluminum chips, which are fairly sticky, everywhere. Yay, grommets!