Hello and a Question?? Detector Repair?

[Macthediver]

Hi Everyone
I'm new here and poking around learning the site. Wanted to say hello and that it is Way cool..I think I maybe a little in over my head as I'm more a hands on learner than tech smart.
That said I was wondering if anyone ever repairs their own detector?
I was using my Fisher 1280X and managed to get water into the control box. I sent it out for repairs and after finding out what the cost would be decided to spend money on a new detector.
Of course I just couldn't leave the old 1280 lay there looking pathetic, so I broke it open. All kinds of little bugs and thingies in there lol. I figured I might see something corroded or loose that I could just fix myself. Well I poked and proded best I could but found nothing that jumped out at me.
The machine has been in pieces in a box now for a couple years. After finding this site I thought someone here might be able to give me some ideas on making it whole again. I wouldn't need it to go in the water I have and Excaliber now. But it would be fun to play with it and see could I make it work.
Anyone got ideas on what to look at first and some simple tests I could maybe do? Even the wiring diagram would help now with it pulled appart. Maybe use parts to just build a different unit all together??

Thanks
Mac

[Carl-NC]

Have you tried to power it up lately? Sometimes a very thorough drying out is all that's needed. The best thing to do when water gets in a circuit is to rinse with distilled water and set up to dry for several days. But it may be that a short circuit has already damaged something electrically, and mechanicals (pots & switches) can also be damaged. To figure it out you really need a schematic, or a good knowledge of what you are looking at. Do a search for "1280" in the Schematics forum. If you decide it ain't worth messing with, I might be interested in buying.

- Carl

[Max]

Hi Everyone
I'm new here and poking around learning the site. Wanted to say hello and that it is Way cool..I think I maybe a little in over my head as I'm more a hands on learner than tech smart.
That said I was wondering if anyone ever repairs their own detector?
I was using my Fisher 1280X and managed to get water into the control box. I sent it out for repairs and after finding out what the cost would be decided to spend money on a new detector.
Of course I just couldn't leave the old 1280 lay there looking pathetic, so I broke it open. All kinds of little bugs and thingies in there lol. I figured I might see something corroded or loose that I could just fix myself. Well I poked and proded best I could but found nothing that jumped out at me.
The machine has been in pieces in a box now for a couple years. After finding this site I thought someone here might be able to give me some ideas on making it whole again. I wouldn't need it to go in the water I have and Excaliber now. But it would be fun to play with it and see could I make it work.
Anyone got ideas on what to look at first and some simple tests I could maybe do? Even the wiring diagram would help now with it pulled appart. Maybe use parts to just build a different unit all together??

Thanks
Mac

Hi,
it's not easy situation if salt water entered the sealed part... anyway you can try to repair (BUT DO NOT TOUCH ANY FIXED POT AND THE LIKE).... just totally disassemble stuff by connectors... so wash boards and other parts with fresh water and let them dry carefully e.g. under the sun for some hours. Then use inside home an heater (e.g. small electrical one of small power) to create hot air flow rising and suspend stuff at a foot distance from it... to keep heating to 40-50°C of stuff and allow complete dry: leave stuff that way for several hours (6-8 ) BUT be careful with plastic stuff... too heat can damage parts so limit temperature to safe values or suspend stuff higher.

Then after wash of salt and drying you can try to recover electrical contacts with specific products : contacts cleaners , usually sold in cans under pressure at electronics shops.

OK: after cleaning of contacts you can remount connectors and all as in original shape , resolder wires if/where needed.

Then at supply phase you need a current limiter : you can find over the Internet any kind of schematics for them but I suggest you mount an LM317 kind with regulation pot : search for "LM317 current regulator" or just read its datasheet to understand how calculate current limit.

(The formula is I=1.25/R where R is the feedback resistance you'll made with a fixed resistor and a pot... but read the datasheet or find a good schematic... you can regulate current from 10mA to 1A that way with LM317T)

Then fix current limit to 30mA first... use a multimeter to calibrate the short circuit current at regulator: this will be the maximum current flowing in your MD when supplied.

General safe procedure is...

Wire the regulator in series with some fresh batteries or a power supply of right voltage and wire an amp meter in series too. Switch on and read current if you already reached the limit of 30mA try up the current by increase of 10mA at each step till you'll see device start working.

If device doesn't start working at e.g. 50-80mA you have some serious problem inside circuit... some short path or burnt stuff.

If you noticed that device works you can also omit the regulator and power it up directly.

Kind regards,
Max

[Macthediver]

Thanks Guys
My unit was never used in salt water so that should be a plus. It was several years ago when it got wet and quit on me and like I stated it has been sitting disasembled in a box. I poked around the site some and found a schematics so I'll have to give it a serious look over. I'm sure I'll be back with more questions once I mess with the unit some more.
Again thanks so much.

Mac