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 Post subject: TC15 in progress
PostPosted: Sat Jun 19, 2021 2:48 pm 
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Couple questions.
1. I'm thinking I can use 60/40 solder throughout the build, but the note about ROHS confused me so I want to check. Guide says to check if turret board is ROHS, but how? Also wondering if 60/40 is OK for the VRM PCB.
2. There's a 47K resistor on the standby switch in the layout but it looks like there's also a note that makes me think it might be optional and some build pics look like they don't have it. What is recommended? UPDATE: I installed it. If that's unadvised please let me know.
Thanks.


Last edited by jeesh999 on Tue Jun 29, 2021 11:21 am, edited 4 times in total.

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 Post subject: Re: TC15 in progress
PostPosted: Sat Jun 19, 2021 5:03 pm 
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Followup:

My readings for the power supply testing on p. 29 of the guide.
119-121-ish for the mains and indicator terminals.
5.2 for 2-8 on the rectifier.
650 for 4-6 of the rectifier (V7).
7.3 and 6.8 for 4-5 on the EL84s (V5 and V6).
6.8 for all the 4/5-9 12AX7s (V1-V4).

Guide says readings will be higher than expected (as in, higher than the numbers in the guide?), and most are only a little higher than those listed, which I assume is OK. The 650 is only one I'm actually wondering about both because it's a big number and so much higher than the others. Is that an OK reading with no tubes?

Possibly related, the (15amp) circuit breaker on the outlet I'm using keeps tripping after about a minute and a half of turning on the amp. Tried it in the bathroom outlet and it tripped the GFI there (not sure it took the same amount of time but I assume so). Any thoughts on what's going on there would be welcome.


Last edited by jeesh999 on Mon Jun 21, 2021 7:53 pm, edited 1 time in total.

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 Post subject: Re: TC15 in progress
PostPosted: Sat Jun 19, 2021 10:11 pm 
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You have a couple of genuine concerns but some are less to worry about than others. 60/40 solder is mostly what I and many of others have used for years without issue but to simplify there is that there is lead in the solder so the warning is for you to be aware of that. It is difficult to solder without physically touching the solder and most of the 'smoke' when soldering is the rosin burning but always try to keep from breathing it (which is pretty much common sense for smoke) and be sure your area is well ventilated that you work in. Don't handle the solder any more than you have to and avoid putting it in your mouth which sounds silly but when working with electronics sometimes the opportunity comes up! You can try lead-free solder but I find it difficult to work with as an amateur and do more damage than good but that may be just me. If using every day all day for a living there could be health concerns.

I built my TC15 in 2013 and other similar amplifiers without the resistor on standby switch but it was not part of the circuit at the time. It was part of a later revision and is not uncommon in other circuits and primarily is a way to prevent audible 'popping' when activating the switch and allows a bit of current to flow to charge the filter caps especially if been sitting for awhile but is not necessary or harmful IMO.

My biggest concern would be the fact that you are tripping breakers in your house yet not the fuse on the amplifier and the high voltage on your rectifier. The GFI in bathroom tripping also may be telling us something. Try powering up without the rectifier tube in the circuit and see if issue continues for starters. I honestly wouldn't move forward until I knew the cause of this. There could be multiple causes and may take some elimination but anything that blows a fuse or trips a breaker MUST be dealt with and cannot be ignored.

Myself I only check the voltages after a build to make sure I am in the ballpark with specs and to spot any serious issues before moving on and do not lose a lot of sleep over a couple of volts here and there until I'm dialing things in or looking for issues but this confidence comes with time. Reading will be high especially without tubes in all the sockets as the loads aren't there like they would be in normal operation.

Read all the forum entries here and for the other Trinity products and on other sites as well in regards to amp building. Part of the journey in amplifier and DIY electronics is the research and understanding what you are doing and why especially if you are new to these types of projects. There is so much to learn and a ton of good information and this kind of mentality to learning goes back to the HAM radio days and further so is not new to the internet age and can be very rewarding. There are many people here with experience and great advise. This isn't the average forum IMO. Research the ROHS scenario as well to alleviate any of your concerns.


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 Post subject: Re: TC15 in progress
PostPosted: Sun Jun 20, 2021 1:37 am 
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BCB2 wrote:
You have a couple of genuine concerns but some are less to worry about than others. 60/40 solder is mostly what I and many of others have used for years without issue but to simplify there is that there is lead in the solder so the warning is for you to be aware of that. It is difficult to solder without physically touching the solder and most of the 'smoke' when soldering is the rosin burning but always try to keep from breathing it (which is pretty much common sense for smoke) and be sure your area is well ventilated that you work in. Don't handle the solder any more than you have to and avoid putting it in your mouth which sounds silly but when working with electronics sometimes the opportunity comes up! You can try lead-free solder but I find it difficult to work with as an amateur and do more damage than good but that may be just me. If using every day all day for a living there could be health concerns.

I built my TC15 in 2013 and other similar amplifiers without the resistor on standby switch but it was not part of the circuit at the time. It was part of a later revision and is not uncommon in other circuits and primarily is a way to prevent audible 'popping' when activating the switch and allows a bit of current to flow to charge the filter caps especially if been sitting for awhile but is not necessary or harmful IMO.

My biggest concern would be the fact that you are tripping breakers in your house yet not the fuse on the amplifier and the high voltage on your rectifier. The GFI in bathroom tripping also may be telling us something. Try powering up without the rectifier tube in the circuit and see if issue continues for starters. I honestly wouldn't move forward until I knew the cause of this. There could be multiple causes and may take some elimination but anything that blows a fuse or trips a breaker MUST be dealt with and cannot be ignored.

Myself I only check the voltages after a build to make sure I am in the ballpark with specs and to spot any serious issues before moving on and do not lose a lot of sleep over a couple of volts here and there until I'm dialing things in or looking for issues but this confidence comes with time. Reading will be high especially without tubes in all the sockets as the loads aren't there like they would be in normal operation.

Read all the forum entries here and for the other Trinity products and on other sites as well in regards to amp building. Part of the journey in amplifier and DIY electronics is the research and understanding what you are doing and why especially if you are new to these types of projects. There is so much to learn and a ton of good information and this kind of mentality to learning goes back to the HAM radio days and further so is not new to the internet age and can be very rewarding. There are many people here with experience and great advise. This isn't the average forum IMO. Research the ROHS scenario as well to alleviate any of your concerns.


Thanks for the reply. To clarify, I did all of the voltage testing with no tubes installed, as I'm just following the builders guide and that's what it specified. Tripping the breakers and GFI are my main worries as well. It's especially weird to me that it's tripping them after about 90 seconds of operation and not right away. That makes no sense to me, but I only know enough to be dangerous.


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 Post subject: Re: TC15 in progress
PostPosted: Sun Jun 20, 2021 11:38 pm 
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I think you have a weird short to ground somewhere that is not in place when the amp is on. If you can wrap your head around how the AC coming into your house works and how one would test for polarity etc without a tester using only a voltmeter than it helps but I'm getting ahead of things.

If it does trip the breaker or GFI without the rectifier tube in the first thing I would do as its simple is to try another AC cord. Pull the one out of your desktop computer if you have one as is the same.

Check really closely at you AC input wiring and socket in the amp itself and really double check the wiring and ground from socket to switch and transformer etc.

It's easy to become blind or what I consider project desensitized to everything in your amp as you've been staring at things so close for so many hours that it can be difficult to see simple errors or anomalies in assembly. Check at the power switch, the light etc. You might have to get medieval and start cutting wires or de-soldering backwards till you get back to the socket but always think like you are dealing with live power even if it isn't plugged in and make sure you take precautions to isolate yourself. I can't count how many times I've become comfortable and overconfident just to touch or cut something and realize I'm still plugged in or have power where I don't expect it.


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 Post subject: Re: TC15 in progress
PostPosted: Mon Jun 21, 2021 12:37 pm 
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Thanks, BCB2. Will do. I would love to know why it's only tripping breaker/GFI after a 90-second or so delay. That defies my limited knowledge of physics (and circuit breakers/GFIs), so I would love to know how that's possible. Any ideas?

Also, the instructions say to "tie off/insulate" the unused 6.3VAC white wire, but the layout (and many build pics) show it connected to one of the (otherwise unused) lugs on the 5-lug terminal strip. Connecting to the strip seems "cleaner" but if that's not advisable please let me know.

Lastly (for now), instructions say to "Twist and connect the two 5.0 VAC Rectifier WHITE and YELLOW-WHITE heater wires to pins 2 and 8 of the 5AR4 rectifier." I see one 5 VAC wire, which is yellow+white stripes, and one 0V yellow wire. I figured the first reference to WHITE is a typo or artefact, so I followed the layout drawing, which shows yellow/white going to pin 8 and yellow going to pin 2. But stuff like this really throws off my confidence.


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PostPosted: Wed Jun 23, 2021 9:28 pm 
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Well the tripping after the fact of the breaker and GFCI can be caused by wires contacting where they should be on your AC side ie. bad cord, polarity of AC wiring etc. Not every 'short' is a 'dead short'. If you take your volt meter and go to your wall socket, when you check across the terminals you should get 110-120 VAC. That's simple and how we check a socket for power of course. Not take the probes and put one into the left hand slot (the longer one) and check to the ground hole. Should be '0' VAC. If you check from the right hand slot (the slightly smaller one) you will have 110-120 VAC! What the heck you say. This is normal and due to the 'polarity' of the AC circuit. The left terminal is Neutral, the right 'hot' and ground is ground. AC and DC are different but so this isn't (+)/(-) but understanding it at that level at least can help understand why this 'short' may occur if something isn't done right. Black wire in wall is 'hot' or 'line' (load to some, no matter), white wire is 'neutral' and green or bare is 'ground'. You will see something similar inside your amp at the IEC socket and fuse. You can think of it as Black (+), White (-) if you want but that can mess you up when dealing with mixed AC and DC devices (like your amp) so bad habit.

Now I'm not sure I have the build instruction version you have but knowing the schematic etc. I believe that the 'unused 6.3V wire' you are talking about should actually not go to an unused terminal on the 5-lug strip but the terminal to attach to is actually the one on the strip that attaches to the mount tab on the strip which will go to chassis ground. This would be confirmed by the schematic and if you look at the strip you should see what I mean. Or it can be left off but I would do as layout and schematic show but make sure it is alone on the terminal as you have 110VAC and 6.3V heater sharing the same terminal strip.

The rectifier uses a 5V heater not like the rest of the tubes which use 6.3V so it gets it's own supply from the transformer. These should be Yellow and Yellow with White stripes. When they say Yellow-White this is what they mean (Primary colour first, stripe colour second). When they say twist together ensure you are just twisting the insulated part of wires NOT the tinned part just to be clear!

The layouts are visual aids to schematics and once you can follow the wires on schematic and do the same on layout AND physically in your amp you will gain more confidence. Its also a good way to double check your work and avoid 'project blindness'!


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PostPosted: Fri Jun 25, 2021 4:41 pm 
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Thanks for the reply. I tried a new power cord from outlet to IEC and it still tripped the breaker (took more than 90 seconds the first time). I may test the outlet but I haven't had any issues with it to speak of, and the amp also tripped the GFI in the bathroom, so seems like polarity is ok. My issue with the 5V heaters is that the guide says WHITE and YELLOW-WHITE when I would expect it to say YELLOW and YELLOW-WHITE. I'm following the layout and build pictures, and the numbers on the trans itself, which show a yellow wire and a yellow/white stripe wire. The current layout drawing seems to show the 6.3 VAC white wire from the PT going to the 5-lug strip, which is what I did.


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PostPosted: Fri Jun 25, 2021 8:47 pm 
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Well we can be pretty confident it isn't cord but is so simple to try that why not right.

I may have been unintentionally misleading you about the wall outlet stuff. I wasn't trying to say was the outlet itself just trying to describe the polarity of AC etc. that could perhaps explain a delayed breaker trip due to wiring.

I don't believe you are really on the wrong track in regards to the heater wiring/colour issue and a test with voltmeter could easily confirm if you have the right wires in right place.

I wouldn't jump around too much and concentrate on ensuring the 120V side of things is OK first visually otherwise you could start removing wires and working your way back to the IEC socket.

Before that perhaps you could take a few close up pictures of everything at that end of the amp like the back side of the IEC socket and fuse, the 5-lug terminal strip, power switch and lamp and transformer.

Like I said, you may have a little 'project blindness' and some extra eyes may spot something you have missed.

Nobody is here to judge you on how beautiful the soldering is and how perfect the wiring is twisted but we might see that one thing you are missing and you can't really move forward until you can get breakers to stop tripping!


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 Post subject: Re: TC15 in progress
PostPosted: Tue Jun 29, 2021 6:23 pm 
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I'm going to create a separate thread about the voltage/circuit breaker issue and post some pics there. In the meantime, here's my turret board with everything (hopefully) in the right place, but with untrimmed leads and only a few turrets soldered. Also don't have all the jumpers or ground bus on it yet. If anything looks bad or wrong, I'd appreciate the feedback.


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