Help repairing Fisher 1265x

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Maybe the switch resistances have gone through the roof over time. Creating unusually large distortion of signal.
If you have recently changed the 4066, then forget about my hunch.

[Koala]

It just occurred to me something. The 4066 is in the signal path. As a matter of fact, it's in the signal path of both the discrim 1 and 2. Just because it's switching properly from one to the next, doesn't mean that it isn't affecting the signal itself. It could very well be the problem.

If you meant U303 the 4016 then yes I have changed it.

[dbanner]

Kinda remember you did.
Oh well, at least the thing works. Is yours the two board 1265x?
I always was keen on building one as possible project, but never got started.
They do turn up on eBay from time to time. Many times for repair/parts.

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I take it that you put in a socket when you changed the CMOS? Wouldn't hurt to try another one different.

[Koala]

I take it that you put in a socket when you changed the CMOS? Wouldn't hurt to try another one different.

Yes I did

[Koala]

Kinda remember you did.
Oh well, at least the thing works. Is yours the two board 1265x?
I always was keen on building one as possible project, but never got started.
They do turn up on eBay from time to time. Many times for repair/parts.

Single board. eBay special. £28. Working ones still fetch £200 or more. Really does like silver and dry ground. Something like a pre 1920 sixpence is well over 7"(over 10" in air) same coin is on the edge of detection at 7" with a T2. Doesn't loose much if the coins on edge either.


Even better is its not fussy on swing speed.


The 1260X isn't far behind easier to build but no pinpoint mode. In some ways I prefer the 1260X. Discrimination is better but slightly less depth.

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The 1260x/1220x has idiotic module, so a layout can't be copied, at least for the module.
Otherwise I would have copied long ago.
With the 1265x, it's all about the availability of quartz and little transformer.
Although it was said that transformer can be omitted, I wanted to make EXACT copy.
Right now I'm just restarted my DMC 2b clone build,. but I will have to do a 1265x copy otherwise It would bug me to no end until I build it.

[Altra]

The 1260x/1220x has idiotic module, so a layout can't be copied, at least for the module.
Otherwise I would have copied long ago.
With the 1265x, it's all about the availability of quartz and little transformer.
Although it was said that transformer can be omitted, I wanted to make EXACT copy.
Right now I'm just restarted my DMC 2b clone build,. but I will have to do a 1265x copy otherwise It would bug me to no end until I build it.

The transformer can be found at Mouser. Not sure about the crystal, instead use a 555 timer into the cd4024 divider ic

http://www.mouser.com/catalog/catalogusd/645/2855.pdf

8ohm to 800ohm see 42TL008_RC or 42TM008_RC

[satdaveuk]

Hi Koala
Have you access to another search coil because that may well be your problem.
I own a 1265x and wouldn't part with it for the world
All the best

[Koala]

Unfortunately not. Only for the 1260x which aren't the same

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The transformer can be found at Mouser. Not sure about the crystal, instead use a 555 timer into the cd4024 divider ic

http://www.mouser.com/catalog/catalogusd/645/2855.pdf

8ohm to 800ohm see 42TL008_RC or 42TM008_RC

Thanks for this useful information. Now I see that the transformer is not going to be a problem.
The quartz crystal is no problem at all. Time to make clone of this great circuit. I'll use original two board layout.

[Koala]

Took it for another test drive.

Looking good. Latest the full 8 hours. Switching between disc 1 and disc 2 is better. Can't remember which way round on way its instant the other there about 1 second before it settles


Glad I persevered with it as it was one of my best days detecting

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Nice.