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PostPosted: 02 Aug 2017, 17:30 
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Joined: 02 Aug 2017, 04:08
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Thanks a bunch for your answeres;-)
I have one transformer, from 220vAC to 12vAC, to drive the board. The other is a torodial transformer, with 2 wires in (220vAC) and 4 wiresout = 2 x 24vAC. Im using one of the pairs for the board, and the other two is driving a 24vAC to 3-12vDC for a 120mm fan. On your build, it looks like you have both pairs going to the board, 2 being connected at the middle terminal. I think maybe my problem Lies there, and have No clue as to where i should start troubleshooting.
Sorry for my bad english, its not my native tounge.


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PostPosted: 02 Aug 2017, 23:03 
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I think I have it worked out. You need a 12V tranni for the filaments. Or a power tranni that has a seperate 12 winding. That goes to the side of the bird where marked.

The power tranni for the chips must have a centre tap or two windings. The tranni hase to be 24-0-24V or 2X 12VAC windings. If the tranni is centre tapped that tap goes to the middle pin of the power tranni connection on the brd. The other two wires go either side. If your tranni has two windings they must be 12V each. Twist the two seize rate out of phase windings together and they go in the centre connection on the brd. The other wires go either side. This gives 24V with a centre tap.

You have to ensure that the two wires you twist together are out of phase from the two seperate windings. So one wire from each of the seperate windings. Use a meter to check you have 24V-0-24VAC before connecting up.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


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PostPosted: 03 Aug 2017, 05:59 
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Joined: 02 Aug 2017, 04:08
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Ahhh, thanx a million to clear that Up. The 24-0-24 was confusing me, and the link allso suggested 2 × 24 vac . I think ill buy a 2× 12 vac, and do ad you suggested.
Is it possible to use the one i bought , and put 2 wires of the 4 in the middle , and the other two in either side og the board?? I have the 12vac tranny for the filaments, and thought a 2 x 24 vac for the board was enough. Its the expression 24-0-24 that confuses me.


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PostPosted: 03 Aug 2017, 06:50 
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Joined: 02 Aug 2017, 04:08
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Im learning new stuff here - think this build was over my skill level, but hey thats just fun :-)
So to clear out my questions : Am i right to assume, that the 24v-0-24v actually means i need a 48vac tranny, preferrable with 3 wires stucking out the secondary side, or could i take the 4 wires from my 2x24vac tranny, each pair has two identical wires with one of Them marked with a sleeve, and take one of each pair and twist together - stick in the middle post on the board, and place the other two in each side og the aforementioned two wires??
Is there any way you could direct me to a working tranny with 3 wires and sufficient Power for this Amp...


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PostPosted: 03 Aug 2017, 19:08 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
Yes you can use that tranni. Do you have a diagram of the tranni primaries?

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


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