F5Turbo Illustrated Build Guide

6L6

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^^ As usual, our esteemed Mr. Hui is correct.

If you are at the end of your potentiometers, the pot resistance + the fixed resistance is not enough to get desired bias to the mosfets, so increasing the value of the fixed resistor will increase the total, and get the job done. If you've got some 2.2k laying around that will work well, but really, it’s not critical at all, you could place an additional 1k in series and it should be enough.
 
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Thanks Dennis & 6L6 -

I doubt I have 8 of them, since I'll need to replace two on each of the four front end boards. I'll order them tomorrow after I reset P1 & P2 on the two boards. Do you think 2.2K will achieve 450mV measured bias? Should I order an alternative size just in case?
Shipping far exceeds cost of the resistors, so why not.
Bill
 
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@andynor, thank you. An 18ga wire barely fits through the holes on there F5 boards without shaving a few bastard strands that don’t make it through. I have 14ga as well but I’d need to trim them way back and I don’t know if I would achieve anything other than what I have. But I’ll do whatever the group suggest if it makes a difference.
 
I see. I tend to think that the makers of the boards size the holes according to what is needed. 18 gauge will therefore be fine, imho.

If you go for anything thicker, you will achieve less resistance, if you manage to cut off the surplus and ensure the rest of the strands touch the solder pad on the top end. But it will complicate the mounting/soldering process, and I am not sure it will make any difference. I would go for 18ga and try to keep the wires as short as possible, but remember to twist them iot minimize loop area.

How is everything going in the rest of your build?
 
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6L6 demonstrated how to use 16 gauge wire for the F5t PCB's. Cut the "extra" strands so that the wire goes through the hole, when soldering the wire, flow enough that it goes to the other side of the PCB and then press the wire down into the solder. That way the strands you cut off are soldered.
That is how I did it.
Only draw back is toasty fingers sometimes.
 
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BB7A172F-24D6-4C19-A54F-E0E88776BDFE.jpg Elwood625, can you point me in a direction for that info? Are there pics?
andynor, not sure how it’s going, I’m a newbie with my first build. Guess we’ll find out shortly. I just ordered 16ga wire and will be redoing my wiring. I’ve included a pic where I’m at to this point.
 

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Luvrockin: This looks like a good first build. I would not stress the 16 gauge at this point. Difference between 18 and 16 is not huge. I recommend you leave it as is, and when all is working and dandy, consider redressing the DC wiring with 16 gauge. Not worth it now, getting to the finish line without magic smoke is more important IMHO. And the F5T and smoke are sometimes symbiotic. Get it up and running, then think of minute changes, is my recommendation.

Cheers,
Andy
 
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At least the power supplies work lol

I would also keep in mind that the distance between your rectifiers and PSU is pretty long. Those wires will contain high currents and a lot of ripple. If you keep that position, be sure to solder the fastons/terminal clips or whatever they are called to the wires, use high enough gauge, twist them really tight and keep them at or close to center of chassis floor for as much of the way towards the PSU as possible. Not saying it is a problem, but if you experience hum for example, it is a potential place to troubleshoot. On the other hand, some distance means more resistance through the need of more wire, and that in turn in fact reduces ripple, if just ever so slightly.

Other than that, I think it basically looks like you are almost ready to rock. What keeps you from connecting the last bits of wire and trying turning it on for the first time?

Good luck! Excited to hear what you think of the F5T. It is in my future build plans/wish list.

Andy
 
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Thanks Andy for the valuable input. I have what’s probably a really dumb question but you mention the wires from the rectifiers to the psu are a bit long. Are we talking about the AC lines into the rectifiers? If so, I wondered if I should’ve twisted those. I soldered them to the boards. I could probably unsolder, twist and re-solder? As for why I haven’t tried powering it yet, I was waiting for different thermistors I had ordered. Those are CL-30’s and I’m replacing them with CL-60’s. Also, I ordered some larger gauge wire which I was waiting for along with some opinions/expertise from the forum before moving forward. I hope to power it up this w/e and hopefully no magic smoke with be let out.
 
Sorry, brainfart. I mistook your ground lifters for rectifiers, but of course, you are using the PSU rectifier boards. Disregard that! Ideally they should be twisted, but keeping them close to each other with for example zipchords also works. The runs are also short so would not unsolder unless you encounter problems.

But where are your AC wires from the inlet ending up? The black and grey one. Are they connected to anything yet? They must be twisted btw.

Sorry for the confusion
Andy
 
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