Whites goldmaster3 or minelab gp

[Goodrat]

GM4

From what I hear, the GM4 should be oposite. If you can verify, that would be great.

[Ray-NM]

Gm4

The pulse is negative with grnd to sleeve and probe to tip about 9 v pulse.
So I looks just like the GM3.
Hope all of this helps. If I could take a screen shot I would.
RayNM

[Goodrat]

Ring

I don't see a connection to ring on the schematic. Maybe with stereo phones pluged in there will be a signal on the ring but then only one ear will have output. Can you see the internal jack easy?

[Ray-NM]

I get stereo on the phones regardless of the switch position on the cable mono/stereo switch. I may opem the 4b later this week and find out how it is wired. Why not contact whites and ask them seems it would be much easier. Rather than relying on what I see. I think both are wired the same probably the tip and first ring are wired together to get signal to both earphones. I put the probe to tip then to first ring and got the same signal.
Ray

[Goodrat]

Whites

I have been in contact with them and they have been helpful. The tech has not seen the older ones in a while. Not too many ask about the jack wiring so I don't get conclusive answers.

The "stereo/mono" switch. That is the final verification! Actually those switches switch from having Tip-Sleeve conected to the speakers or in the other position you have Tip-ring connected to the speakers in most metal detector headphones to accomodate Minelabs and Garrets that use tip + and ring -. It shouldn't be called a stereo/mono switch but it usually is. If you get sound in both speakers then we can conclude that the tip and ring ARE shorted in the machine. All makes sense now. This is typical. But this depends on what phones you are using. If you are using typical stereo phones where the stereo/mono switch simply shorts and un-shorts the tip/ring, then you would have the results you get.

So we have: 1) with scope ground to sleeve, negative pulses on either the tip or ring 2) the tip and ring are shorted in the machine. 3) your headphones short or unshort the tip and ring.
Negative at the tip, what were they thinking!