An illustrated guide to building an F5

[Boofers]

6L6 nice work on the amp and very nice writeup. Thanks for sharing.

[WithTarragon]

I also commend 6LC for a nice pictorial.

It is unfortunate these threads stray so much, since they lose their value very quickly.

[6L6]

It most certainly does matter how you pair the windings, whoever you talked to didn't understand your question.

The transformer has 2 primaries and 2 secondaries. Each of those is a winding of a single wire around the core. Therefore you only have 4 wires around the core, with a total of 8 ends.

It's an Antek, so we know that the primaries are Red/Black, and the Secondaries are Blue/Green.

Also, we know that the primary leads are one black and one red. Also the secondary leads are one green and one blue.

Get your multimeter, and set it to continuity. (the setting where it beeps if you touch the probes.) put the probe on one of the black primary leads. Now touch the reds, one at a time. One will beep, that red is the mate to the black you are testing. Twist them together. Now double check that the other red and the other black also beep, and twist them. Those are now your 'A' and 'B' primaries.

Same thing with the secondaries - grab a blue, and test continuity to the greens, only one will beep. Those are mates, twist them together. Double check the other ones, and twist.

[Zen Mod]

oh boy

here we go again.....

[Russellc]

Originally Posted by 6L6

flg, CanAmMan, russellc -




russellc - My understanding is that the toshiba FETs need a slightly lower value, like you said, the common value is 1.5k . I too, invite people to share their observations and experiences with this. My case is most likely because the input FETs where all the way towards one side of their range, and the outputs on the other side of their range, and because of that combination of wonkyness, needed quite a bit more R to get the bias flowing. Anyway, it was a easy fix.

I'm just joking about jacking, You did it the right way, post the whole thing at once, then let the info flow however. What output devices did you use in this build? IRF, Fairchild, or Toshiba? I assume not toshiba? I'll have some input soon, already have the standard value in place, I'm preparing to order 1.5K just in case. I'm using the Caddock resistors and doubling them would be difficult, so if it wont bias up, I'll just have to carefully change them...I do have a couple of spare boards just in case I trash one changing them out.

Thanks for the response,

Russellc

[Russellc]

6L6, I just caught your statement about the input/output fets being "at one end of the range" and find this very interesting. What was the measurment of your input/output fets? I have more than one set, so I have some choices. I have suspected these little fets may make some difference in that resistors value needs to be. I would like to develope a feel for what "range" causes the variation, so any input much appreciated!

Russellc

[Russellc]

Originally Posted by h_a

By the way,



no need to worry, it's close to impossible to lift a trace with modern fiberglass boards; not like in the old times with the paper boards where it was a piece of cake

Hannes

Not hardly. I have easily seen both the Cviller as well as Daniels boards with lifted and vaporized trace / pads, even with the greatest of care. Make no mistake, these two boards are very delicate in this regard. Best to avoid resoldering if at all possible. 6L6 did a nice job in his recent thread, and in a very effective way....unsoldering only one end, adding a series resistor to the empty hole, then soldering the two loose ends together. Half the soldering equals half the risk!

Russellc

[Russellc]

Originally Posted by 6L6

It most certainly does matter how you pair the windings, whoever you talked to didn't understand your question.


Get your multimeter, and set it to continuity. (the setting where it beeps if you touch the probes.) put the probe on one of the black primary leads. Now touch the reds, one at a time. One will beep, that red in the mate to the black you are testing. Twist them together. Now double check that the other red and the other black also beep, and twist them. Those are now your 'A' and 'B' primaries.

Mybe I'm not understanding, but I was going to twist both red primaries together and both black primaries together, to the power input. I am obviously getting confused and perhaps this isnt the connection being dicussed. My first F-5 is dual mono with 2 tranformers and that is the way I did them, black to black, red to red. OK, tell me where I misunderstood so my headach will go away! (I am finding the single transformer version to be more confusing than the dual one I built) Thanks for the help and the nice pictorial, helping in another way as well, this time I am using a single Daniels power supply board like yours and your pics answer many questions.

I think you are talking about the connections to the CL-60s maybe? which I havent yet installed. I can see this is where a few builds may have gone bad....

Well looking at the first watt schemo I see what you are saying about the primaries now...not properly pairing them up could result in a lot of havoc, especially where they cross over to the CL-60s.

Russellc

[merlin2069er]

here's my setup so far...

[Marra]

First picture of the bridge you appear to have the positive connected to the negative of the p/s board[negative of the capacitor] it should go to the centre ground point.