Should I repair it?

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	Should I repair it? « on: March 11, 2009, 05:46:53 am »

My old faithful Discovery 2-box (the model with a meter) died for good last year. It served me well, and didn't cost me much back then. I've since bought a new TF900 (no meter on it). I've been toying with the notion of fixing up the old detector and keeping it as a backup unit.

I'm on the other side of the planet from Discovery Electronics' factory. Sending the old detector there and back again by courier would cost around US$170 with insurance. I suspect that all the circuitry will have to be replaced along with the knobs and switches. Would it be worth my while to have such a refurbishment done, bearing in mind that a brand-new unit cost me US$580 inclusive of courier charges and full insurance? Your input would be much appreciated.

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	Re: Should I repair it? « Reply #1 on: March 11, 2009, 05:56:24 am »

Hobbyist . Is there no one in your neighbourhood that can help you ? There certainly must be some electronics hobbyist close to you that could be of servise to you . The schematics of a two-box are pretty simple so help should be available . Try it ! Cornelius

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	Re: Should I repair it? « Reply #2 on: March 11, 2009, 06:56:28 am »

Cornelius,

Metal detectors are not common over here, and I have taken the unit in to several electronic boffins, including a chap who repairs Furano radar, and only met with negative results. The internal components are a write-off.

Perhaps I should have mentioned that the unit and I took a 15' fall from a rather steep hillside into a rather muddy pond at the bottom. The detector was on at the time, and totally submerged. Don't ask me why I was playing spiderman there...its a long story.

In any case I suspect that it may not be worthwhile to repair, and unless my imagination is overactive, my new 2 box seems to be more sensitive than the older one ever was.

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	Re: Should I repair it? « Reply #3 on: March 11, 2009, 07:28:24 am »

Can you get the schematics of that Two-Box unit ? ( the old one ) or maybe the schematics from the new one ? I am looking for a long time to get my hands on one of these schematics , but in vain sofar . It would be possible to use the old PC board and making notes of the components and their position on the board . It would then be possible to rebuild the unit with new components . This is something I would like to do . But .......... Huh?

?? Regards Cornelius

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	Re: Should I repair it? « Reply #4 on: March 11, 2009, 08:08:36 am »

Cornelius,

The full extent of my knowledge on electronic devices stops at inserting the batteries or plugging it into an outlet and fiddling with switches and knobs. However, your request intrigued me.

I found the schematics to a TM808 (which should be somewhat similar if not totally identical to the TF900). Please surf to

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. They have it in zip file as well as viewable attachments.

My TM808 is still in the Philippines. The hot season is already here, and I can't wait to compare it to the new TF900!

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	Re: Should I repair it? « Reply #5 on: March 11, 2009, 08:16:12 am »

I forgot to mention...I scrolled further down that webpage I mentioned in my last posting, and there's 2 zip files pertaining to the schematics of the TF900. It's all greek to me, but I'm sure you'll have fun with it!

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	Re: Should I repair it? « Reply #6 on: March 11, 2009, 11:52:48 am »

	Quote:	Posted by Hobbyist
My old faithful Discovery 2-box (the model with a meter) died for good last year. It served me well, and didn't cost me much back then. I've since bought a new TF900 (no meter on it). I've been toying with the notion of fixing up the old detector and keeping it as a backup unit. I'm on the other side of the planet from Discovery Electronics' factory. Sending the old detector there and back again by courier would cost around US$170 with insurance. I suspect that all the circuitry will have to be replaced along with the knobs and switches. Would it be worth my while to have such a refurbishment done, bearing in mind that a brand-new unit cost me US$580 inclusive of courier charges and full insurance? Your input would be much appreciated.

Hello Hobbyist , I do not think you will have to replace the whole circuit board , unless it sank in the ocean . How old is the Machine , is it still in warranty ? If you decide not to send it to the factory , just carefully take the two-box apart and check for corroded / broken wires or connections . Smell for burnt components or look for popped electrolytic capacitors , also battery corrosion !! Search coil wires corroded ? A lot of things you can do . Also if you have a "friend" that is a TV repair Technician with an oscilloscope . He can check where the battery supply , power supply voltages are present or not . Check if you have oscillation or RF present at the search coil . In my opinion Discovery makes the best Two-Box on the Market ......... Also , I would hate to see you spend two or three hundred dollars TOO MUCH !!! You are very welcome to post clear Digital photos of your Discovery Two-Box PCB " Circuit Boards" on this Forum , then I can tell you where to look with an oscilloscope or voltmeter , some good test points !!! The final decision is yours ....Best Regards....................Eugene52

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	Re: Should I repair it? « Reply #7 on: March 11, 2009, 12:40:33 pm »

Hello Eugene,

I thank you for your very kind offer of help. It didn't sink into the ocean..it fell into a muddy pond together with me and a pair of headphones while it was on. I had left it with my friend to look at (he repairs radars and probably has one of those oscilloscopes you mentioned), and he once again confirmed that the board was shorted out and "beyond repair". A few other tv repairmen before him had also said the same thing.

Now if it's gonna cost me $200-300 to get all the innards replaced (and I would prefer replacing everything rather than just a few parts, to be on the safe side), I guess that means it's not worth repairing. No worries. It cost me about US$170 second-hand in the late 90's and has paid for itself many times over. I do agree with you completely; Discovery makes a lovely 2 box, and that is why I bought a new unit last month. Sturdy American quality! It should last me another 10 years or more, unless I fall into another body of water again.

Eugene, you seem to be most familiar with the TF900. I would like to ask you this: is the new TF900 without the meter is more sensitive than the older model which has the meter? When I snapped together my new unit and tested it, it seemed to pick up my septic tank faster and louder than the old one ever did. Thank you again for your kindness.

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	Re: Should I repair it? « Reply #8 on: March 11, 2009, 04:24:35 pm »

Hello Again Hobbyist . If you decide not to fix it . Then take it apart and finish drawing out a schematic , if you have spare time !! Here are two pdf folders that were posted on Geotech and also posted on Patent websites . Use Clip magic software to extract the schematic photo and convert it to jpeg , print then fill in the blanks . It would be nice to have a complete schematic . If not then I am sure later on someone will have all the TF900 schematics . Thank-You for posting Hobbyist , you have two great Machines and one can be fixed without major problems !!!

Best Regards................Eugene52

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	Re: Should I repair it? « Reply #9 on: March 11, 2009, 05:23:45 pm »

You give up too easy! Did the pots get wet?

Can you just flush it out with clean water and have it worK??

Send the board to me and I bet I can make it work!

Jim

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