White's Coinmaster 4D GED-4D schematic and info?

[g-man]

Hi folks, I'm new here. I just got a White's Coinmaster 4D (GEB-4D) with a date code of KI. The problem is that mine appears to use 2 battery packs plus another battery on the door, but I can't find a schematic that shows the one on the door (assuming a 1.5v AA). Also, the pictures on the label appear to show the 2 battery packs in a configuration different than what the actual battery pack holder would use (the holder looks like it would take a 6- and 8-inline pack rather than the 2-row packs). I would like to get this working so that I can try out the hobby before investing in a more modern detector, so any help appreciated. Pictures below.

[dbanner]

The schematic for the White's coinmaster 4 shows two power supply voltages. The first is 12V(8x1.5V)powers main circuit, and the second is 9V(6x1.5V) powers audio amplifier. It doesn't matter if you've got in-line or double row battery packs. There should be two packs, one at 12V and the other at 9V.

[g-man]

I'd agree, but if you look at the photo you'll see that there are places for 2 battery packs, and then there is a single battery holder on the door. The battery holder on the door connects to the pads shown in this photo:


So you can see my issue. Even the label appears to show a different style of battery pack than what this was intended to take, so I'd like to know if there was some variation. Also, if anyone knows what the date code indicates then that might help in my search. Thanks.

[Carl-NC]

The single socket is just a battery cell tester. With the unit in the OFF position, plug a AA battery in the socket and it will drive the meter.

[dbanner]

Ray-o-vac batteries, oh boy, that's a long time ago!
The last two digits of the serial code might indicate 1974.
The battery packs may have been replaced at some point, those old batteries leaked horribly if left inside for a while.

[dbanner]

You may want to give the circuit board a good look over, make sure the components look ok. Any electrolytic capacitors maybe dried up or out of spec after so many years and may need changing out. Also check the solder side for any possible dry solder joints that may need touching up, these things happen with old stuff. Clean the contacts, spray the pots, the usual stuff.

[6666]

Like dbanner says two packs 12+9, before you drop in the packs put a loop of thin cotton ribbon in the holder so you can pull them out, they can get real tight .
Also on some models, (not sure about this one) had a switch on the front to test the battery packs, on the meter face was a section that showed good or bad batteries and I think it said a voltage

[dbanner]

.

[g-man]

Thanks Carl-NC! That's very helpful! Ok, so now off to find some battery packs that fit. Thanks all, this was very useful.

[Skippy]

I have restored a Whites of similar vintage to this one, and the electrolytic capacitors were all in poor health. I replaced all of them in the end, though it was the larger ones that were the problem. There was a low drop-out linear regulator circuit ( discrete transistors ) that had an electrolytic on the output. Just as with LDO IC's this cap is important to the regulators stability. My dried up cap stopped the regulator functioning, it was doing some kind of 'motor-boating' , trying to turn on and collapsing repeatedly. The weak main power rail caps also made the entire machine noisy, and I ended up fitting double the capacitance that was originally used, with audibly less hiss as a result.

Getting this old beast working may not be the best introduction to detecting. There are plenty of 'modestly old' machines available that are sufficiently good they will give you an enjoyable introduction to detecting, without the down-sides of true vintage machines ( weight, poor ergonomics, dozens of batteries, hard to set up/adjust etc ).

[profesor]

https://www.geotech1.com/pages/metde.../US4024468.pdf.
This is a patent guess scheme.

[Melbeta]

I used to be a Whites metal detector dealer, and I used to take in used Whites metal detectors. Most of the time the problem was bad battery packs. So I ordered a bunch of the two different kinds of battery packs. So still got a lot of them in storage in case you cannot find any of those old time battery packs... And back then, Ken White SR told me, every one you take in, send it to my attention. It has my name of the machine, and I will repair them for you for free. And I will update (revise) them to the last known revision, again for free. Did he do it? Yes he did. The only cost I experienced myself was the shipping cost to Ken White SR's personal attention. He even paid the return postage back to me. Did any other brand name manufacturer do the same thing if I took in their metal detectors? NO, they did not! Was he a good man with me? YES he was. Was he a good man with others? I do not know and cannot answer that last question. But he WAS WITH ME!!!!
Melbeta

[scrungy_doolittle]

https://www.geotech1.com/forums/atta...1&d=1520198791 here is a link to the schematic.