Echoplex EP3 tape head wiring polarity

[clarisso11]

Hi everyone,

I've been repairing an Echoplex EP3, and after lots of help from this forum, I have identified a dead record/erase head as the problem.

Yesterday I received a replacement, but I'm unsure about the wiring, especially since the colour of the wires is different.

Old tape head - Erase: White (to ground), Black. Record: Red (to ground), Orange.
New tape head - Erase: Yellow (positive), Blue (negative). Record: Red (positive) Orange (negative)

If the record head is colour coded the same, positive seems to go to ground. If the same is true for the erase head, yellow should go to ground?

I have attached the schematic, hope that helps.

Thanks!

[Enzo]

And the difference it makes is what?

[clarisso11]

And the difference it makes is what?

I guess my real question is: Does it make any difference? I'm hesitant to just wire it up in different ways, since I don't want to risk damaging anything.

Sorry for my lack of knowledge here, I'm wondering if polarity matters at all.

[J M Fahey]

Just thinking aloud, both Record and Erase receive AC (Audio+ HF biasing and strong High Frequency erasing signal) so *in principle* polarity should not be a big deal.
As in: "AC has no polarity"

Not high power involved either, so trying it both ways "should" be safe.

I would NOT mix Record and Erase heads though, but physical position should indicate which is which.

Connect them one way, try to Record/Play/Erase, meaning use it as a regular Echo unit, thenn invert wiring to see whether it vworks better or worse.

I would not expect any difference, but I might be surprised, testing rules.

[clarisso11]

Just thinking aloud, both Record and Erase receive AC (Audio+ HF biasing and strong High Frequency erasing signal) so *in principle* polarity should not be a big deal.
As in: "AC has no polarity"

Not high power involved either, so trying it both ways "should" be safe.

I would NOT mix Record and Erase heads though, but physical position should indicate which is which.

Connect them one way, try to Record/Play/Erase, meaning use it as a regular Echo unit, thenn invert wiring to see whether it vworks better or worse.

I would not expect any difference, but I might be surprised, testing rules.

Hey Juan, thanks for helping me figuring this out (and understand), much appreciated. I've gone with Yellow and Red to ground with great results, so I will leave it at that.
Amazing how much you can learn on this forum!