Marshall 1987X crackling distortion

[dorrisant]

No sweat... Glad you got it rockin'. That is a lesson that you won't forget very soon.

Also, those dots indicate the polarization of the windings. It really doesn't affect your OT situation much but helps when connecting PT dual primaries in series or parallel. Pay attention to those dots then.

[cassiddidy]

No sweat... Glad you got it rockin'. That is a lesson that you won't forget very soon.

Also, those dots indicate the polarization of the windings. It really doesn't affect your OT situation much but helps when connecting PT dual primaries in series or parallel. Pay attention to those dots then.

Well, yeah but it definitely effects the OT when there is NFB involved (and when what is labeled as one end of the winding is actually the center tap!)

[martin manning]

You're right about the importance of the phasing wrt nfb. A multi-tap secondary must have the common lead going to ground so that the 4-8-16 taps will have the correct impedances.
I've never seen anything like the dot markings on the diagram attached to the box, but white is clearly the CT since it's shown as being in the middle of the coil. I always test new transformers for turns ratio and phase to confirm the connections and the impedance ratio.

[cassiddidy]

You're right about the importance of the phasing wrt nfb. A multi-tap secondary must have the common lead going to ground so that the 4-8-16 taps will have the correct impedances.
I've never seen anything like the dot markings on the diagram attached to the box, but white is clearly the CT since it's shown as being in the middle of the coil. I always test new transformers for turns ratio and phase to confirm the connections and the impedance ratio.

I was thinking that white was the CT when I first got it, but when looking around online I start to wonder how uniform these diagrams really are

I think that's a good practice that I'll have start next time I do a transformer, actually checking impedance ratios and stuff. Until then, maybe I'll email Hammond to give them a little feedback on the dots...