Metropoulos Forum

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This just seems weird to me. On the 50 watt OT's the blue is the center tap and the red and white ones go to the plates correct? Is that what the black dot on top implies?

I've always seen that the primary 'center' tap was in the 'center' of the diagrams, or am I wrong and the white would be the center tap on this PT?

Also, I did a quick search for this and couldn't find an answer... I know it's common for people to reverse the OT primary taps on accident. Is there a way to figure out which one goes where, without just following the color? Let's say for example that all the wires were the same color. Is there a way to find out which goes to V4 and which goes to V5, or would it have to be trial and error in that case?

Hope that makes sense, Thanks!

White is the center tap that goes to the b+ voltage

Cool, thanks. It's kinda weird that they didn't follow the normal color system.

Do you think I should try Blue to V5 and Red to V4?

Can anyone help me out? I got the OT, but I can't figure which sockets to put the primaries. Based on other diagrams I've seen, my instinct says blue to V5 and red to V4, but I'm not 100%.

Your instinct hasn't failed - correct!

Larry

Also make sure you connect the red wire to the power tube that is driven by the input side of the PI.

For future reference... how do you figure this out? I know the center tap thing is obvious, but how would I figure out which primary goes to which output tube if no one told me?

I depends on the maufacturer. On the OT drawings and layouts etc, some manufacturers denote it by different means. For example on all of the heyboer transformers I have used, the Primary on top of the drawing is usually the "Start" or the input side of the PI connection. Magnetic Componens illustrates the "end" with a black dot, so in that drawing the blue lead is the "end" or negative side of the PI, so the Red is the input side.

Awesome. That helps a lot!

So is the common of the secondary always at the 'end' as well?