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Help-Mod on RM7A gone bad!!

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Help-Mod on RM7A gone bad!!

rockpup
Well I went and broke my Relic magnum.Did my first mod and well.......
Its all done-but..Broke the tone pot!

Its not working right now at all.The TR does not seem to work.It doesnt seem to Gb.Whats goin on man!
SO SAD!

Could this broken tone pot be the problem.I suspect it is.Any ideas there is 3 connections on the board to the pot for the tone control.Could I wire in a resistor of some sort of value to compesate for the missing pot?

Any help be nice.I will show the pictures tommarro-kinda lame because its not working right!
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Re: Help-Mod on RM7A gone bad!!

Paul (Ca)
Rockpup,

Post a picture of the boken pot,  I'm sure one of us has a spare to send you.

Is it the volume pot?  If it is you can by pass the adjustable volume and wire it so it's at full volume, Keep us posted sounds like a minor problem.

Cheer up, We'll help you get the RM7A going again

Paul (Ca)
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Re: Help-Mod on RM7A gone bad!!

rockpup
Ok I have to wait till some better light from MR.Sun.Its the tone control Pot.Its a small kinda looks like a tuning pot from a transistor radio.I did not realize there was a small plastic nut holding the tone control plastic knobby dial on the circuit board.

I looked over everything again-its all good but that broken pot.Running real weird-like close objects broken-little depth loss-fair away objects sound off better.

Im guessing the pot was a 2 way-top and bottom plates.I will post the pictures as soon as I can.
Im guessing that the tone control works 2 way-Im hoping can just hotwire straight across-may give real high tone?
Im guessing if I used differant size resistors it will give me differant tones?I would have to look up some cicuits in my electrical handbooks-may shed some light.

I will post a picture once I tear it apart again and get some better light.

I know one of you guru's will have the answer.

If I cannot fix-someone might be the lucky owner of a modified compass corspe LOL.
Someone might get a early x-mas gift.

Chris.
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Re: Help-Mod on RM7A gone bad!!

rockpup
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Re: Help-Mod on RM7A gone bad!!

rockpup
Ok Its apart again.dont really want to take off all the knobs so I cannot show front of circuit board now.
Its sure weird and everything is the same Except that tone potentiometer (dont ask me how to spell lol)
Here's some pictures:



I think its marked R413.

3 connections into the circuit board-2 on top one on bottom.I think they all run to differant circuits?Remebering from last night-dont think 2 are bridged-kinda confused on that-making me think the pot was dual function?Like 2 in one pot? Really not sure how to connect with out it?

Be great if someone had a spare lol not sure what its resistant is-cant test its messed up man-whoops.

Any hints suggestions be very helpfull! Thanks Guy's-I hope this works! It was worth it-cant use the thing for long the way it was.



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Re: Help-Mod on RM7A gone bad!!

rockpup


Thats a better shot of the mod.Mounted the trigger switch as a trigger switch-that was a pain.That  I could not figure out-the only thing I could do drill big hole-push in switch into smaller hole on bottom  and cover with electrical tape.I checked all my splice's and resoilder connection-there all fine.

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Re: Help-Mod on RM7A gone bad!!

rockpup
Yup its that pot.I cannot find a value or anything.Unless someone has a old relicmag and can steal the pot,I think its fubar.

At the moment, I am going to paint it.I filled some holes.It will look a little better.
Its for sale tommarro,Im thinking.
Will post some updated pictures.
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Re: Help-Mod on RM7A gone bad!!

Melbeta
rockpup wrote
Yup its that pot.I cannot find a value or anything.Unless someone has a old relicmag and can steal the pot,I think its fubar.

At the moment, I am going to paint it.I filled some holes.It will look a little better.
Its for sale tommarro,Im thinking.
Will post some updated pictures.
I used to see a lot of small pots very similiar to it, but not exactly like it. What I saw were pots with a screw driver slot in the place of that center hole. In yours, it does not have a screw driver slot, it has a knob shaft that must stick up through the case housing.

So all you need to do, is take a reading with a voltmeter, remove the batterys, set the voltmeter to read resistors which is ohm readings. It probably is a 10K. Read the two legs on right side, just as your photo shows. Then you can repace it with a standard pot, with a small shaft. You can wire the three legs to the PCB, to the three places. The left side leg, is the center leg, called the "wiper" leg. So when you turn the pot, it tunes the tone sound, by changing the amount of voltage running between "0" volts to whatever volts are in that place. In other words, if it is a 10K ohm pot, it is tuning (in the wiper position), the ohms from the low ohms of "0" ohms to up as high as 10K Ohms.

Now in my explanation I am using 10K ohms as a guess. It may be a 5K pot, a 1K pot, or other values. Radio Shack will have a pot that will replace it, once you have figured its value. You photo does not show me any markings on it, or I would know right away the number of ohms on that pot.

Now once you have that value, if you are not interested in bringing the pot back up to the detector face again, you can put in a PCB board pot, we commonly call them I.F. Pots, for Intermediary
Frequencys, with a screw driver slot, and adjust it to the tone you want, and leave it permanent at that tone.

In fact, any small pot, that has three legs, in that "tri-angle" hole configuration, you can use, as long as you can fit it in, and it is the right ohm value, and you can solder it into the board. If it is a two sided PCB. what we call a double sided board, or a "through the board" board, which makes contacts to each side of the board by using the holes with contact through the holes, then to make contact on both sides of the board, you would have to solder the legs to both sides of the PCB. You can tell if it is a double sided board, it will have traces on each side of the board, and a continuity meter touching on each side of the board, will show continutity (connection) from each side ot the board to the other side of the board, at that particular place where the three legs go through the board.

This photo, I am showing you similiar pots, these pots are 100K value, you can see the numbes on it. The two legs you see, are what we call the bottom legs, which you would measure side to side, to get the ohm value, that top leg, is the wiper leg. The wiper leg is further away from the other two legs, and kind of in the center position from the legs. I hope I am not confusing you, I am trying to explain it so anyone person can understand it...
Melbeta
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Re: Help-Mod on RM7A gone bad!!

Melbeta
See, here is your photo, and the left leg is the adjustment leg, when you turn the pot, it changes the resistance that is there between the two right legs. Measure the two right legs, with a voltmeter unit that has resistance measurement ability. But make sure you remove the batterys first, as you do not want to damage the voltmeter when it is set on resistance measurement scale.

the value between the two right legs, is the value, such as 10K or whatever the resistance reading is. If you have questions, let me know. I am going with your photo as that is all I can see of this part. Look at my photo that i sent first, and you can see there are other types of PCB parts, and I bet Radio Shack will have them, or they will give you a specific part name and you can find it on the internet.

You can get solder braid from Radio Shack, solder braid helps you use your solder iron, and suck up the solder from that pot, and then the pot legs will have no more solder, move the legs around a bit as you suck up the solder into that solder braid, and suddenly you will see that each leg of that pot is suddenly "free" and loose, and when you have sucked the solder from each of the three legs, you can lift that pot right up, and off of that PCB, and they it will be in your hands. Then look under it, it may have a name or numbers there.

If you can get the value of that PCB pot, I may have a pot with the screw driver slot on it, the same value. I do not have any with the shaft like it was originally though. Those were a special pot.
Melbeta
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Re: Help-Mod on RM7A gone bad!!

rockpup
Thanks dude that sums it all up.Im sure my meter has that function-been sometime since I tinkered in electronics-

If I want to jumper it, with a say 10k  resistor if that is close.I would conect the bottom leg, to the left top leg-jumper with resistor across to the second leg?

Thanks If i can get a value or close value I will just hard wire so its a higher tone.Im asuming the less resistant the higher the tone.

Not sure if anyone else has a pcb tone pot-im sure there pretty close to the same value on all.
Im guessing 0 - 100K ish?

If I cannot figure it out its going to be for sale-highest bidder on this forum only.Just wanta little compensation for my effort if all else fails.Thanks again guys.

Chris.
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Re: Help-Mod on RM7A gone bad!!

Melbeta
In a message dated 3/24/2011 9:59:25 AM Mountain Standard Time, [hidden email] writes:


Thanks dude that sums it all up.Im sure my meter has that function-been sometime since I tinkered in electronics- If I want to jumper it, with a say 10k  resistor if that is close.I would conect the bottom leg, to the left top leg-jumper with resistor across to the second leg?


   Chris, you can do it that way if you want, or simply put a small pot in the opening in the detector case lid. Then take three wires, and run it down to each of the three holes. Then you have the same effect as the original pot. As long as you install a pot of the same value as the original pot, just put a new pot in the lid hole.

Oh, I think I understand your problem. Pot clearance problem? The board will be in the way. So you put your pot in a new location that will not be touched or nudged by the existing board. Or put the pot on the bottom side of the board, it will work the same way and probably not clearance problem that way, unless it strikes the battery holder unit. But if you find the same flat pots, like in my photo, you will have not trouble! And can adjust the tone. rather then settle for the tone that a fixed resistor will give you.

Or find a small board pot like the one that was in my first photo, and turn it so the audio is the way you like it, that way if you sell it, and someone does not like your setting, they can turn the screw driver slot, with a plastic screw driver unit, or something that is not metal, as metal affects the top of the adjustable pot. Use your finger nail to turn the slot, and it is good...


Thanks If i can get a value or close value I will just hard wire so its a higher tone.Im asuming the less resistant the higher the tone. Probably, but not sure, I would assume the more voltage it permits, the higher the tone is. But it could be the reverse.

Not sure if anyone else has a pcb tone pot-im sure there pretty close to the same value on all. Im guessing 0 - 100K ish? 
That pretty well covers the range I would think it is, and even though I am told I am not as smart as some here, I will guess it is near a 10K pot. You would expect it to be a narrow adjustment pot, so maybe even a 1K pot or 2K pot or 5K pot. Going up to a 50K or 100K pot would be pretty wide adjustment band. It probably adjusts between "0" and "6" volts.

If I cannot figure it out its going to be for sale-highest bidder on this forum only.Just wanta little compensation for my effort if all else fails.Thanks again guys.

   I would be interested in it, have looked for one, want one that does work, or that I
can fix the problem like your problem, as I have a 12" grey decal brand new coil, if and I want it for buried caches. So keep me in mind too...Does it have a black plastic connector, or the traditional Compass metal connectors? Melbeta


Chris.



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Re: Help-Mod on RM7A gone bad!!

Paul (Ca)
In reply to this post by rockpup
Chris,

I once broke one on an X-100, Looks like the same pot as yours and that one was for the Tone as well.

What I did was jump two of the legs,  This places it in a fixed tone position. Can't remember which two legs I soldered together,  Give it a try it should work pick two legs and connect them and try another two legs until it works right.

Keep us posted,
Paul (Ca)
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Re: Help-Mod on RM7A gone bad!!

Compassdealergirl
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Re: Help-Mod on RM7A gone bad!!

rockpup
Sold the machine.
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