Whites goldmaster3 or minelab gp

[Goodrat]

I need info on the audio output circuitry of either of these or the jack wiring.
Anyone at least have one?

[amtech2005]

IC Question

Hello, Just wondering if there is a substitute for LM318 or ICL7660, Thank-You Amtech2005

[Goodrat]

Technical help

Any out there who has either of these machines that knows how to work a meter and can make a measurement at the output jack? No need to open it.

[Ray-NM]

Goldmaster 3

Goodrat I have one what do you need to know?
Ray-NM

[Goodrat]

What do you have available, meter, scope? I need to know what is coming out of tip, ring and sleeve if you plug in a stereo plug. Or maybe with the unit off, just an ohmmeter measurement between tip ring and sleeve.
I need to know if there is any connection to the sleeve. I would like to know the polarity of the pulses most likely positive at the tip with respect to ring.

[Ray-NM]

I will try to take a look tonight.

[Goodrat]

I sent a private message Ray.
If you don't get that, email [email protected]

[Ray-NM]

Sent your answer in two different emails.
Ray-NM

[Goodrat]

Sleeve?

I just answered your message asking if sleeve is shorted to tip?

[Goodrat]

Also

Also, is this 11v at no load?

[Goodrat]

Your kiddin'

That would mean that this machine has a negative pulse train with respect to ring! Also the ring is shorted to sleeve. I hope none of the newer machines from Whites do this.
Do I understand this right Ray?

[Ray-NM]

I think so

Yes that is 11 v unloaded I suppose it will be less when I plug in my Koss qz5.
I believe I am right on the post I sent you about the sq wave and what I measured. Got to leave for a meeting now so if you have more questions I will have to check or recheck tomorrow night.
Ray

[Goodrat]

See your messages

I have the info finally from Whites. THe ground is 68 ohms to V+ and the tip is driven low with a transistor collector that is pulled up with a 100 ohm.
I'm not sure how the middle ring comes into play.

[Goodrat]

TRS

A drawing to get the lingo straight:

[Ray-NM]

Another look at this.

Looked at the drawing and my readings were with probe on tip and grnd on sleeve. the output is a negative pulse. I also get negative pulse on the ring. That was with the headphones connected or not to the plug. With the headphone cable disconnected from the plug (I unsoldered it)I get zero ohms from tip to ring and 165 from tip to sleeve. I also have a Whites GM4b but have not checked signals on it yet. If you like I can look at it tonight. I agree that depending on which direction you have the diode placed will block the signal.
For what reason do you have it in the phones.
Ray