Internal GB trimmers on Fisher 1265X

[JoeR]

Does anyone know how to change the preset groundbalance on the Fisher 1265X?What trim pots are involved?

[Sean Goddard]

Yes! Check out the Fisher 1265 schematic on this forum. The trimmer you need to twiddle, is the one at the front end amplifier after the coil. BE VERY CAREFUL, it is VERY EASY to screw up the performance in all metal even though the Disc more may still work. It's part of the great design of this unit **cough...splutter***

BTW it's easy to work out which one it is on the PCB, it's the one near the LT1007 amp. DO NOT slip wit hthe screwdriver, these amps are nearly $27 a pp, and they pop REAL EASY!

[Carl-NC]

Sounds like the voice of experience!

[JoeR]

Re:1265x trimmer

Many thanks Sean!!I will take a looksee but you may have scared me out of trying it.

[JoeR]

Opps!

Sean,I can`t seem to find a 1265X schematic on the forum;a search turned up nothing.:confused:

[stjepo]

Have you found it?


Regards

[Sean Goddard]

Visit http://www.pulsar-electronics.co.uk and leave me your email address I'll email you the complete 1265/6 schematics and layouts.

About two years ago, I went through the whole circuit taking snapshots of the waveforms as various points. I then overlayed these on the schematic I had, took me weeks, but it looked cool and was a great help for setting up the 1265 and 1266.

One point to note is that if you alter the all metal channel in a 1265/66 then you will screw up the WHOLE machine, and the disc as well. They are VERY difficult to set up correctly, BUT.... If you set up a 1265/6 properly you can gain upto 4 inches in ground depth over the Fisher standard factory specification. This is a BIG increase!! The only problem is is that you can take 10 machines, 8 will set up great, two won't improve over factor at all. Looking at the diagrams, there is no clue at all as to why this happens.

[stjepo]

Sean Goddard

Your link don´t work. Takes us to a dead end.

Regards

[Geo]

Hi Sean Goddard I think that last Christmas you wrote at this Forum that now you work with China detectors. So do you have schematic from md5002 or md 5006. I want to modify them so is easier if i have schematic
Thanks
Geo

[JoeR]

Problem with link

Sean,there seems to be a problem with the link.I located Pulsar-electronics by doing a search and that link did not work either.I appreciate the offer for the 1265/1266 schematics very much, however, and hope to see the link working soon.Thanks.

[ivconic]

Visit http://www.pulsar-electronics.co.uk and leave me your email address I'll email you the complete 1265/6 schematics and layouts.

About two years ago, I went through the whole circuit taking snapshots of the waveforms as various points. I then overlayed these on the schematic I had, took me weeks, but it looked cool and was a great help for setting up the 1265 and 1266.

One point to note is that if you alter the all metal channel in a 1265/66 then you will screw up the WHOLE machine, and the disc as well. They are VERY difficult to set up correctly, BUT.... If you set up a 1265/6 properly you can gain upto 4 inches in ground depth over the Fisher standard factory specification. This is a BIG increase!! The only problem is is that you can take 10 machines, 8 will set up great, two won't improve over factor at all. Looking at the diagrams, there is no clue at all as to why this happens.

This is usefull...
Is there ay chance we can get that schematic with your adds, here?