Faulty Fisher CZ21

[Cornishkiwi]

Hi All

I have a Fisher CZ21, love the thing.

But some how left it on and noticed batteries were dead. So replaced them and now I either get a constant phone ringing noise when on pinpoint and nothing when go to detect mode. Or sometimes it just is fully unresponsive, however still makes the noise when turning it off and on or when test the battery (on the Sense function), (I tested it on the beach and wasn't picking up anything I lay down) and doesn't seem to change between pinpoint and normal detect.

I mostly dive with it to be honest but inside the compartment was pretty dry so don't think it has had water ingress.

I'm leaning toward battery issue only because that was the last thing i changed with it. I tested the block and am receiving 19v out the top (with fresh 9v batteries. On the pin ends that connects to the battery block i am also receiving 19v. There is a little nick in the outer sheething of the wire i noticed and wondered if this would cause such drastic effect (see photo). Otherwise I'm worried I've done something major. The pins are gunked up from previous owner so if possibility of that then I will start to clear it and make good.

Otherwise there are screws in the battery compartment to enter into the main body but i don't know enough to just start taking apart and playing.

Also of note is I've wiggled the wire and no obvious change.

Currently out sailing with it (which is why so gutted was nice to get and do some out of the way detecting) currently quite remote so any help would be very much appreciated if there's any possibility of fixing myself. If its something that would need proper attention then will have to go from there.

Thank you in advance

Keiron

 

[Carl-NC]

With the battery connected and the detector turned on, do you still get ~18V at the terminals?

It sounds like water ingress to me. It might have leaked the last time you used it, but took a while for corrosion to set in and cause damage. It only takes a single drop of salt water.

 

[Cornishkiwi]

Yeah, and constant which is what made me believe it wasn't that.

But good point, there wasn't any signs on the batteries or anything else such as rust marks anywhere or salt residue. Maybe i'll redo the terminals anyway as precaution. Otherwise from there i feel i may have to open up the next compartment to check (but i'm not sure what to expect or ensure i do no extra damage in the process)

 

[Cornishkiwi]

Also an additional thing to add, while viewing this morning, the screw pin for the battery backing plate doesn't look fully protected (See attached). Is there a possibility water could enter here and into the main body?

 

[Carl-NC]

the screw pin for the battery backing plate doesn't look fully protected

It's a hot-injected threaded insert and sits in a blind pocket, it does not extend into the housing.

Remove the 4 screws in the battery compartment and then slowly pull on the faceplate. It may help to loosen the 4 screws and then push on them to break the gasket loose. All the circuitry will slide out with the faceplate.

 

[OBN]

 

[Cornishkiwi]

It's a hot-injected threaded insert and sits in a blind pocket, it does not extend into the housing.

Remove the 4 screws in the battery compartment and then slowly pull on the faceplate. It may help to loosen the 4 screws and then push on them to break the gasket loose. All the circuitry will slide out with the faceplate.

Ok perfect i thought that may be the case, but just wanted to cover all options.

So once re sealed that faceplate gasket should hold again?

 

[Cornishkiwi]

That's perfect, thank you so much.

When putting back together again nothing needs to be dont with faceplate gasket? it should just be water tight fine again?

 

[OBN]

Been many years, fairly sure I changed nothing... I would suggest calling my friend Steve Noga who works on them, I know he has repaired several of my friends Fishers back in the day... Also you will have to leave a message for rarely does he answer.
Oldtimer who made his own underwater metal detector in the 80s with a CZ5..

One of his visits this year we airtested his WP CZ, amazing it tested a few inches better then the new Legend 2

 

[Cornishkiwi]

Oh perfect I'll give him a message, thank you!!

Sounds like the man in the know that's for sure! What an absolute beauty haha

 

[Cornishkiwi]

Hi again, not sure if people will still see this or whether to start a new thread.

So i replaced the battery wiring, and checked inside and everything seems ok.

The detector is turning on fine, and battery test working ok.

My thinking is maybe the coil must be dead/dying. hence why was working a bit before. But now the coil is completely unresponsive it seems.

I took the coil cover off, and as you can see from the photos it looks like the potting has cracked slighly on the edges. so i was wondering is the coil itself fully potted? or would these side cracks allow water into the coil and the salt has slowly eaten parts away or shorted out etc.

Is there any way of testing it? And if so how? A multimeter seems the way for resistance on the terminals? but what exactly would i be looking for and what figures would i be getting?

And finally is it possible to just buy a new coil?

Thank you

 

[Vito]

Hi again, not sure if people will still see this or whether to start a new thread.

So i replaced the battery wiring, and checked inside and everything seems ok.

The detector is turning on fine, and battery test working ok.

My thinking is maybe the coil must be dead/dying. hence why was working a bit before. But now the coil is completely unresponsive it seems.

I took the coil cover off, and as you can see from the photos it looks like the potting has cracked slighly on the edges. so i was wondering is the coil itself fully potted? or would these side cracks allow water into the coil and the salt has slowly eaten parts away or shorted out etc.

Is there any way of testing it? And if so how? A multimeter seems the way for resistance on the terminals? but what exactly would i be looking for and what figures would i be getting?

And finally is it possible to just buy a new coil?

Thank you

That can be the damage.
Never saw such damage on my coils.
Makes sens. If the wiring is corroded, it will need more space.
I do not know what has to be measured with a digital multi meter.
Best testing is to hook up a coil known to be working.