Input mod for Minelab SD2000

[Woody.au]

This is an easy modification that will improve the depth and sensitivity on a Minelab SD2000 and/or their other detectors that use a LM394 in the front end. The mod is really easy, just remove the LM394 and install a SSM2210.
They are pin for pin compatable except that the SSM2210 has much lower noise. The noise figure is about half that of the LM394.

[Woody.au]

You can optimise the noise figure and gain by adjusting the resistors that are associated with the front end matched transistor pair. This is a real experimenters mod and is a tedious process.

[ZED]

Hey Hey Hey!!!!!!
Woody i recognize that sloppy hand writing anywhere!!!!
I sure hope you checked that schematic up against your own 2000 to make sure it is correct.
Dave Emery....well i never .

Woody and Members good job on the mystery IC,it had me puzzled for years.
So that 16 pin chip above it,what do you suppose that one is woody???????

ZED

[Woody.au]

It is part of the VCO audio generation, I had the number written down and now I cant find it, will put up the other chip numbers when I find my notes.

[Ismael]

The IC above is 4093.

Regards Ismael
www.minelabmods.com

[ZED]

Izzy could be a 4053 .

Nice sunny day in melb today,going detecting,got a modded GP3000 to test.

ZED

[Ismael]

according to some info I have it's a 4093 but... Who knows for sure....

Regards Ismael
www.minelabmods.com

[Stefan]

Can't be a 4093, this is a 14 pin quad 2 input nand. However the 4053 is a 16 pin analogue multiplexer.

Regards,

Stefan

[Ismael]

Hi Stefan, actually the IC above is a 14 Pin not 16 as was stated. Below is a picture of the layout and IC's we know:






Just to add to these images the ones in blue are actuals that I know for sure and the pink are from circuit diagrams I have. This is updated as I do know some of the missing ones but have misplaced that info!!

Regards Ismael
www.minelabmods.com

[ZED]

I may have mixed things up here,the thread is about an input mode but i went of on a tangent and spoke about the vco.The 16 pin chip i am referring
to is the one above the 16 pin dip package [mystery chip] at the vco end of the detector.
The gates on the front end receive are controlled by a nand gate chip.

ZED