Minelab Detector Repair Advice Needed

[John W]

HiI Everyone, First post to PA. I have been "lurking" for a while because I got sidetracked reading different forum posts. Great reading I must say. Anyway, to the reason for this post. Back in the 80's , I purchased a Minelab Goldseeker 15000 from a professional detector/prospector. I'd hardly used this machine and put it away shortly after purchase in working condition. I was recently having a clean up and discovered the detector. I hooked it up but unfortunately it doesn't work. New batteries, terminals all clean. Don't know what's the matter. Not electronically mined enough to pull it apart and have a look. Any ideas as to what might be wrong or somewhere to take it to get it checked. I live in Hunter Valley NSW. Too old to go detecting now. Hips and knees are kangaroo edward.
I'd like to get it fixed for sale. Thanks.

 

[grubstake]

Hi, John - welcome to PA.

From my understanding, the component most likely to deteriorate from old age in an electrical circuit, is the electrolytic capacitors. A technician familiar with thru-soldered circuit boards should be able to identify the issue relatively easily, but whether substitute components are readily available is another matter. The resale value of this detector would likely be around $150 at best, so repair may be unviable.

There's some previous discussion of this model here:
https://www.prospectingaustralia.com/threads/goldseekers-15000-metal-detector.34256/

 

[John W]

Hi grubstake, Thanks for the prompt reply. Following your comments, I might see if I can take the cover off and see if there's any evidence of a burnt out capacitor. As I said, it hasn't been used for over 30 years and it was working when I put it away. I'll let you know how I get on. Thanks again.

 

[grubstake]

A capacitor won't be "burnt out" by non-usage, but may be swollen or corroded. However, it may just be dead internally, without visually-obvious damage. If you happen to know anybody who works on old, valve-powered amplifiers or radios, they'll be very familiar with the problem, which was where I learnt about it.

 

[John W]

Thanks ol' son. I'll see what I can find out.

 

[axtyr]

G'day John.

There might be 3 issues with the detector. As grubstake said, a swollen capacitor. Electorlytic capacitors are the cylindrical tubes and have a flat top. If they swell up then the tops will look as if they are about to pop open, they will no longer be flat. Google electrolytic capacitor and you will see what we mean. I can't remember if they painted the circuit boards of the 15000, but they may have, in which case everything inside will be painted white.

Another issue might be a dry solder joint. This means the solder has dried up and has lifted off the circuit board. If that has happened then that could be extremely difficult to find.

The third issue might be as simple as one of the wires to the battery holders has broken away from either the battery holder or the circuit board. Just be careful opening the box. disconnect the battery holders first.

If you are going to dispose of it please let me know, I might be interested.

Regards Axtyr.

 

[John W]

Thanks Axtyr, I'll have a bit of a squiz and see if I can spot any damage. I'll let you know how I get on. Thanks.

 

[John W]

Checked the battery wiring and it's all ok. there's power to the circuit board. Can't see anything wrong with the capacitors. Don't know how to check for anything else. Hopefully I can find someone nearby to have a look at it. I'd prefer to sell it in working condition.

 

[John W]

After a bit of investigation, it looks like the detector is actually working, it's just the inbuilt speaker that's not working. It works fine with headphones. I contacted Minelab about a replacement speaker but they don't carry spares for a machine that old. It is their first machine afterall so that's understandable. Could someone please tell me what speaker I'd need to replace the dud one? It's not visable without pulling the circuit board out and I really don't want to do that without having a replacement. Hoping someone can point me in the right direction. Thank you.

 

[grubstake]

You just need to know the diameter that fits, John. You can get a "replacement speaker" from Jaycar in 57mm. 76mm or 100mm (or smaller sizes), for around $6:

https://www.jaycar.com.au/57mm-all-...838d663cc9c&sort=relevance&searchText=speaker

 

[John W]

Hi grubstake, thanks for the info. It looks like it's about 45mm. Bit difficult to measure accurately in situ. Probably pull it apart now and measure it accurately and see if I can buy something close. Thanks again, I appreciate you help. I'll let you know how I get on. Regards, John

 

[axtyr]

John, don't worry too much about the speaker. We all used headphones back then. I didn't think about the speaker. It's annoying to put something away working and turning it back on later to find it is playing up.

Good luck with it, regards Axtyr.

 

[John W]

I'm a dot the i's cross the t's sort of bloke and it annoys me when something doesn't work as it should. Also, I don't like selling things that aren't working perfectly. I'll have a look and see how much is involved in replacing the speaker.
Thanks eveybody for your input. Much appreciated.
Regards, John

 

[gef12]

Could even be the headphone jack .. this makes and breaks contact with the speaker ..
just my thoughts

 

[John W]

G'day gef12, It seems to work ok with the headphones, but the speaker in the detector doesn't work. No reaction unless the headphones are plugged in. I understand what your saying. I've had similar problems in the past with headphone jacks and plugs. Not in detectors though, know bugger all about them, but other electrical equipment. I contacted Minelab in South Australia and a service bloke there is going to look through the archives and see if he can find anything about the speaker. I think grubstake's on the money with Jaycar. That'll be the best bet. The bloke at Minelab probably thinks the 15000 should be classified by the National Trust. )

 

[Jaros]

Mine called Minesaw--half of is anyway--bits and pieces .

 

[John W]

G'day Jaros, you don't have a working speaker for one by any chance?

 

[Hilux]

see if there's any evidence of a burnt out capacitor.

Look for round electrolytic capacitors like this;



If its been unused look for brown gunk discharged from the base of them onto the circuit board like this;





If it had been used a lot then sometimes they bulge at the top.





Sometimes the glue used to stabilise the capacitors against vibration ages and becomes conductive causing issues.


Perhaps try to sell it cheap noting it's defect. Someone might want to purchase it as a project.

 

[John W]

G'day Hilux, Thanks for the reply. The circuit board looks fine. No bulging capacitors. It's the actual speaker that's not working. The detector works fine when headphones are plugged in. Just no sound when the headphones aren't plugged in. I'm looking at replacing the the speaker. I'll probably sell this when I get the speaker replaced. It's in really good condition. I have the original Minelab carry bag, original headphones, manuals etc.

 

[Hilux]

Hi John - sounds like an easy fix then. I missed reading that in the comments!