Wiring Question (Answered)

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Re: Wiring Question (Answered)

Post by JMPGuitars »

DH166 wrote:
Sun 08/29/21 4:57 pm
For the love of Pete, you're startin' to wear me out! :x Alright, I'll go back over it. And I'm using a solid state rectifier. I'm going off your schematic and the layout dated 10/2020. I misinterpreted that layout, which shows those wires stranded separately (I guess for clarity of color distinction). So my plight now is that all those wires are trimmed for length. I can de-solder and start over, but I'll have to splice to make them long enough. So is it sufficient to splice, solder, and tape those wires, or do I need to install three more terminal strips?

Pardon my obvious frustration. I am genuinely grateful for the help and the prompt replies.

Hopefully, at least, some other first time builder will stumble across this and benefit from my errors. Sheesh.
No worries, you're not the first person frustrated by some of this stuff. We've all been there at some point!

Whether or not you use a terminal strip, or splice wires is up to you. If you do splice them, do a really good job. Make sure there's extra insulation, and maybe double the heat shrink if you can.

There's also lots of options for terminal strips. For example:
6-lug-terminal.jpg

The best bet is to plan ahead, ask questions in advance, and then move forward. There's lots of galleries here (under Gallery and Archive on the left navigation menu) with tons of build photos to give you ideas.

If I knew how to neatly twist wires in Visio, I would, but I never bothered to learn. Sorry. ;) ;)

I think the easiest way to answer the question of "should I redo this part?" is to think if you saw the photos of the amp built that way, would you buy it? That's not to sway you in one direction or the other, only to consider the quality of the work done once the choice is made.

BTW- lots of other users on here could show you the progress they made from their 1st to 3rd or later builds. Experience makes a world of difference, as does feedback on here.

Thanks,
Josh
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Re: Wiring Question (Answered)

Post by DH166 »

Josh,

Alright. Re-did wiring from the PT to mains and switches and from the OT to selector, twisting and adding right angles. As a side note, since with your build I have the layout and schematic but not a manual, I have been using the Trinity 18W builders manual as a rough guide for the order in which to build (wince. competitor. I know). Of course, at each step, I'm making sure that everything I'm doing (to the best of my knowledge) correspond to the components, values, etc inside my actual chassis. Which leads to my next question. This design uses a solid state rectifier. The manual I'm using (again, just referencing for build step order. I know, components and values vary), indicates testing the power supply at this stage of the build by measuring voltages across the iec terminals, the terminals on the switch, the socket of the rectifier (which socket I obviously don't have), and the sockets of the power tubes. So, couple questions:
1. Do you agree that testing these voltages is the correct step for this point? (again, VERY carefully. I know. Lethal voltages)
2. How do you measure the voltages on the solid state rectifier? Since the two sets of diodes run parallel into the 100ohm resistor, and each row has its own lead from one of the 290V taps on the PT, do you measure each separately upstream of the resistor? Do you measure after the resistor?

Thanks as always
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Re: Wiring Question (Answered)

Post by Bieworm »

You can perfectly follow the Trinity guide. Stephen knows his stuff very well!
I also test the power supply when wired. Don't forget to add the DC from the rectifier to the filter cap.. or you can not test the B+. Be aware these are "unloaded" voltages, thus higher than the eventually wired up amp.
The rectifier measuring points are the 2 HV AC wires going in and the B+ at the
conjunction of the outcoming DC voltage.
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Re: Wiring Question (Answered)

Post by JMPGuitars »

What Bieworm said. And it's all good, we like Trinity around here. They're certainly one of the better sources/resources out there.

Thanks,
Josh
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Re: Wiring Question (Answered)

Post by geoff 1965 »

I agree,that Trinity build guide is very thorough,also you get great feedback from them if you ask about any of their amps.
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Re: Wiring Question (Answered)

Post by DH166 »

Bieworm wrote:
Sun 09/05/21 11:35 am
You can perfectly follow the Trinity guide. Stephen knows his stuff very well!
I also test the power supply when wired. Don't forget to add the DC from the rectifier to the filter cap.. or you can not test the B+. Be aware these are "unloaded" voltages, thus higher than the eventually wired up amp.
The rectifier measuring points are the 2 HV AC wires going in and the B+ at the
conjunction of the outcoming DC voltage.
So, that's the part I'm asking about. Remember, first time builder here. I didn't catch most of that. The 2 HV AC wires going in. Is that here?
Screen Shot 2021-09-05 at 5.49.58 PM.png
And the B+ at the conjunction of the outcoming. Is that here?
Screen Shot 2021-09-05 at 6.04.36 PM.png
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Re: Wiring Question (Answered)

Post by JMPGuitars »

Looks like you did catch that. ;)

Either side of that 10W resistor could be measured as your B+ DC voltage. That resistor is there for sag, to simulate a tube rectifier.
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Re: Wiring Question (Answered)

Post by DH166 »

Got it. Thanks! Next question. My PT came prewired and has leads for 5V on one side and 240 on the other that aren't used in this build. What do I do with those? Do I just roll them up or clip them short and get them out of the way? Are they carrying either of those voltages away from the transformer? I clearly don't want 240V flopping around in the chassis. Do I need to tape up and heat shrink the ends of them closed?

Side note: In a previous post, I stated I was building the Modern Classic. Actually, it's the Tremolo TMB.
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Re: Wiring Question (Answered)

Post by JMPGuitars »

DH166 wrote:
Sun 09/05/21 6:32 pm
Got it. Thanks! Next question. My PT came prewired and has leads for 5V on one side and 240 on the other that aren't used in this build. What do I do with those? Do I just roll them up or clip them short and get them out of the way? Are they carrying either of those voltages away from the transformer? I clearly don't want 240V flopping around in the chassis. Do I need to tape up and heat shrink the ends of them closed?

Side note: In a previous post, I stated I was building the Modern Classic. Actually, it's the Tremolo TMB.
You got it. Clip the ends, heat shrink the ends with extra heat shrink hanging off, and tie them off.

I'm glad you've been taking the advice about lead dress, with the Tremolo TMB build you want to make sure it's all as good as it can be.

Thanks,
Josh
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Re: Wiring Question (Answered)

Post by DH166 »

Ok. I've never been accused of being the world's smartest man, but I am intelligent enough to realize I need to know EXACTLY how to measure and test voltages, so as not to fry my amp or myself. I searched this forum, as well as youtube for 'measuring power supply voltages in a guitar amp', a search string I thought would generate lots of useful results, but found very little. Can you point me to a good tutorial?
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Re: Wiring Question (Answered)

Post by Bieworm »

Perhaps you can read what Paul Ruby states in his powering up an amp guide?

https://paulrubyamps.com/info.html#FirstPowerUp
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Re: Wiring Question (Answered)

Post by DH166 »

Alright. Been a few weeks since I got to work on the build. Next question. I wired up the output jacks as shown on the layout (pics below), and when I test for ground, I'm grounded not only on the lugs on the outer side of the jacks (those connected to the black wire from the OT and the gray wire to the star ground, which is yellow in my pic because I didn't have gray) but also on the innermost lugs, those attached by the blue wire to the output selector. That doesn't seem right to me. The jacks themselves are insulated. I tested them and they don't ground out. Am I just mistaken, or doesn't this mean that the signal coming from the OT will ground out before it reaches the jacks?
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Re: Wiring Question (Answered)

Post by JMPGuitars »

If you test your OT secondaries with no connections to anything, you'll get a continuity beep when it's not powered on. Never test continuity with the amp powered on. If you disconnect the ground connection, you will still get continuity between the secondary connections to the negative (black) wire, but no longer to ground.

Most of the wire colors in my drawings are to keep things clear, you can use whatever you like.

Thanks,
Josh
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Re: Wiring Question (Answered)

Post by DH166 »

Ok, thanks. So, it sounds like you're saying everything is as it should be. Just to clarify, I was measuring continuity (with power off) between the lugs on the jacks and the chassis ground, and likewise between the lugs on the selector and chassis ground, and getting a beep on all of them. So, that's right? In terms of signal, then, how does it get from the OT to the speakers without grounding out?
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Re: Wiring Question (Answered)

Post by Bieworm »

Because there is no connection to ground from the selector switch. The speaker will be the resistive path to ground.. otherwise there would be a short, and that's a no-no!!!
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Re: Wiring Question (Answered)

Post by DH166 »

Ok. Thanks. So now at this point I'm ready to start putting the passives on the turret board. A question on that. How do I find the outside foil end of my caps? I don't have an oscilloscope and I tried the fuzz pedal method and didn't get any difference in hum level. This build is my first tube amp. I just have a Fender modeler and I'm guessing its software is made to eliminate hum from pedals in the first place. Ideas for figuring this out?
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Re: Wiring Question (Answered)

Post by Bieworm »

There are some methods using a disassembled instrument cable.. use Google for the details. But you could buy the sozo caps when you don't have a scope to do this. Sozos have the outside foil side truly marked with a stripe
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Re: Wiring Question (Answered)

Post by TriodeLuvr »

Not all caps have outer foil. Depends on the construction method. Maybe try a few different types to see if any of them respond to the method you're using.

Jack
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Re: Wiring Question (Answered)

Post by JMPGuitars »

Jack and Bjorn make good points. If you don't want to invest in an oscilloscope, the easiest thing is to just get SoZo caps. They're great caps, especially after being broken in.
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Re: Wiring Question (Answered)

Post by DH166 »

Alright. October was a busy month but I'm back at it. Bought a second hand old Tektronix and got the caps figured out. Next question: I'm about to wire up the input jack. I recall reading about how to hook it up with the shielded wire, but I can't find the article I read. Does the shielding get soldered to the ground lug? Does it just get clipped off and heat-shrunk out of the way? On the layout, it just shows the shielded wire going to the tip side lug and a separate wire going from the sleeve side lug to ground. So, the follow-up question would be likewise for the other shielded wire coming off of V1 and V2. How do they hook up? Thanks
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