Update on the Whites GMZ - "It lives"!
I found the receipt and bugger me, the guarantee actually ran out on July 12 this year. I was about to post it to Goldsearch anyway when a work colleague suggested a mate of his, Frank, who works for Mechtric here in Adelaide. So I spoke with Frank, (who owns a Whites GMT), and while no promises said he would give it the once over.
Below is his email back to me.
Hi TT. I had a look at your GMZ last night and the news is good... it's fixed. White's use a voltage regulator
to reduce the 12V from the battery pack down to 8V. The whole circuit runs on 8V and by doing this, you get
a fairly long life from the batteries as the voltage has to drop below 10V before it stops working (it needs a 2V
differential). Anyway, the regulator had blown. They can do this, especially if they are low-spec (meaning cheap).
Luckily, I had some good ones in my parts bins at home, so I replaced it and it burst into life. I discovered that
this unit runs totally quiet till it finds a target, then there is a sharp beep. I presume that is how it should work. It
detected a 2.5gram nugget at 4" so I have to pronounce it as all OK. I also noticed that the centre leg of the
ground balance switch had become desoldered, so that had to be fixed. You may have had erratic ground noises
before from intermittent contact.
I could've brought it back today but I want to hook it up on the bench tonight to my frequency counter, to make
sure the 50kHz frequency hasn't drifted. There is provision to adjust this and it is important. The coil is optimised for
this frequency and you don't need to be far off for it to have an affect on performance, i.e., depth.
So I will bring it back tomorrow and it should be fine for a long time.
Cheers for now,
Frank
Very happy with this outcome, and cost me a slab.... sweet :lol: