Looking for White's Coinmaster 5/D GEB Supreme Schematic

[KRinAZ]

Hi All, it's model CM5D (it's not the DB model), date code KP (would love to know actual date for that) and it works in GEB mode, but is wonked on all 3 Disc modes as far as I can tell (just gives loud tone all the time in high and medium, can't tune it, and low never tones, can't tune it either). Maybe it's me but I read the manual (ok quickly glossed it) ...

It's surprisingly clean and nice for it's age, what a shock to run this after a modern detector but once I figured it out it actually works pretty well as long as I leave the Disc modes alone. Found a relic first time out...

So I thought I'd take a shot at repairing it, schematic would be so helpful. Also if anyone knows of any components that especially always need to be checked on these or just always replaced that would be helpful also. Any tuning info or voltage or signal test points/checks would be great.

I've heard these can be retuned to seek gold (freq change?) and if anyone has info on that I would be in heaven!

I just got this off Craigslist to use while my beloved Whites GMT is in for repairs (gives me a chance to go back to old sites and search for relics this time instead of AU).

OK, thx!

[Qiaozhi]

Is this what you're looking for?

[Carl-NC]

The good ol' days before opamps...

[KRinAZ]

Is this what you're looking for?
Thx much Qiaozhi, test points, waveforms, and all, cool!
It looks though like that is for the earlier version CM5 which is similar to but different than the later version CM5/D (from what I understand the newer CM5 base circuit had the capability of having the discrimination added, & when added makes it the CM5D). I will hang on to that schematic for any part of it that looks to be in common, still seeking the CM5D schematic though...

.

[KRinAZ]

The good ol' days before opamps...
;^> hard to imagine there was a day when discrete transistor circuits were the state of the art!...
Hey Carl did you ever happen to come across the specifics of the CM5D tweek to higher freq for seeking gold? I'm thinking [in addition to the tx freq change and different coil] the receive preamp section with the TA control would need a tweek for the higher freq input? & maybe other tweeks?

.

[WM6]

The good ol' days before opamps...

Except (complicated) coil, schematis is really nice piece of transistor era design.

[KRinAZ]

OK, update on the functionality of this detector - check this out!

The Disc does in fact work, thought I'd spend a little quality time with my new/old detector, read the manual again, went back out to my open area in the front yard, and tried to ground balance. It was going crazy when I moved it just a couple inches and sometimes could/sometimes couldn't ground balance - tone just screaming all the time, seemed unstable. With it still on, I was holding it waist level, I started walking back to the house - about to give up on it - and it quiets, hmmm. I move to a different area of the yard and scan around and lots of target sounds. I find a fairly clear of targets area, get good ground balance and scan, lots of targets everywhere. Confirm I can repeat good ground balance in my clear area, go back to the previous area and it's screaming again - at waist level.

Long story short, I live in a 100 year old house in a mining district. Using this detector I find large deep targets all over the yard. Target rich environment. Can't wait to dig some and see what I find!

So - what was going on - right under where I was initially trying it out in the yard, there is some giant target and I get a signal so strong I have to hold the coil up at about 3' to weaken the signal! No wonder the controls seemed wonked! In an area relatively clear of targets I can get good GEB and over "normal" targets the Disc seems to work as per the manual.

This target that was under me is so big I get a clear signal and can trace the outline of it while holding the coil at 3' - lower and the detector is just screaming full tone, coil 3.5' - 4' off the ground and it at least sounds like a normal strong target. This target is about 4' by 6' rectangular and easy to define the border. I wonder if it's a metal roof section covering something, I haven't dug it yet.

With this in mind, I start scanning the yard and found I can clearly trace the water pipes while holding the coil more than 2' above the ground - and the pipes are buried 24".

And, another mistake I was making - I wasn't far enough from the chicken wire fence when I was initially playing with the CM5D. There is a 3' wide gate of 2" pipe with chicken wire and I get a detectable signal from it starting at 4' - I have to be more than 4' away from it to be clear of detection!!!

Now I really want a schematic to keep it running, this thing is unbelievable for sensitivity to high conductive targets. Always wanted a cache/relic hunter, guess I found it. Detectable depth appears to be up to 4' for big targets, wow.

This weekend I'm going to start digging targets and see what I find...

[KRinAZ]

On second thought, I'm going to leave the CM5D in it's original form (won't do mod for seeking gold, my GMT is just fine for that) - especially since it's working so well (and 40 or so years old!) - it's going to be very handy when seeking large deep targets...