Problems with your Harbor Freight Cen-tech pinpointer? How to fix em.

[Leopard11]

Yup it goes mad when pointed up but point straight its fine, another reason I added the knob heh

 

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[rlc1940]

Ya know, I ordered a white's bullseye II along with my atpro. I used a borrowed white's pointer along with a detector ( my Daughter's) before I ordered. I really liked it! After watching videos, I really don't want too much sensitivity on the pointer because of rust and oxide deposits, etc. The white's has about an inch of sensitivity which is about right when you dig a hole and start looking. If the item is not heard on the surface or in the hole, you haven't reached it yet! Dig a little deeper and bingo...there it is! Very easy to X the object and pick it up. I was an avid detector hobbyist in the 70's, found thousands of coins across the eastern U. S. without a pointer. Had to swing the detector coil over the hole a lot! I really like the pointer, helps out! Never used a knee pad back then either...but I do now!

 

[OverKill]

Yes Golem,
Mine does the same

 

[mcockrell]

I hate resurrecting old threads but I thought I would weigh in on this because there were a few problems people had mentioned but didn't get answers to.

I bought my CT on a Saturday and within 30 minutes the switch was already messing up and you really couldn't tell whether it was on or off. so I put it away and classified it under useless junk and lesson learned. then I scanned the internet a bit and saw the switch mods and sensitivity mod so I decided to try it. I put in a new switch very similar to the old one but much better. spent a few minutes fine tuning the sensitivity. took it out and it worked like a charm. it was definitely worth the $16 for sure. would I rather have a garrett pp? YES! but I, like most people who buy these, just cannot justify that kind of money on a pp. especially if you are new to the hobby and really not sure if you'll still be interested in it a year from now.

that being said, for those worried about soldering the switch, there is no need to be worried. you don't even need any solder. all I did was heat up the solder iron and touch the point on the old switch where the wires are currently soldered. I moved the iron around and collected more than enough solder on the iron to use for the new switch. pushed the wires into the new switch and rubbed the iron around and it worked perfectly. no solder needed.

the sensitivity mod worked really well too. but don't be too hasty when you are doing this mod. most sites I went to basically said put your external knob to 1/2 then crank the internal pot until it just stops beeping and youre done. well I have found that this isn't always the case. when your PP is in the ground it can throw the sensitivity off by quite a bit. sometimes I have to turn the external knob nearly all the way down for it to stop beeping constantly over nothing. take a few minutes and try different settings on the external knob and internal pot. you'll find that you can really tune it in if you have time to work with it a little bit.

some other mods: I wired the vibe motor into the same wires as the speaker. it worked quite well. but after experimenting with it a little I found that it can increase the range quite a bit when the light isn't on. so I wired a switch to the speaker and the motor so I can toggle between the two, or have both. I also wired a switch to the LED so I can use it when I want (those last couple of digs on the way to the car right after sunset). its sometimes a hassle to carry around a flashlight. im already carrying 5 or 6 pieces of gear! so now I can get the range but I can also use the light if I want.

one other thing I did was tape up the hole covering the speaker. that helped out a lot with dirt and dust and sand getting in there. plus, I think the volume of the beep is way too loud. at one time I also covered the speaker with tape too.

mine also has problems every once in a while where it will beep constantly for no reason even after turning down the sensitivity. what I did was drill a small hole in the case on top of where the internal pot is. its normally covered with tape also but I can remove the piece of tape and turn down the internal pot and it fixes it. just remember to turn it back up. from my experience this happens when it gets very hot. I have read a forum where a guy wired a thermistor to his and he never has to adjust it even in extreme cold or hot weather. I haven't tried this but recently my wife and son have gotten the MD bug so chances are I will soon buy another centech and try this mod.

one of the other problems ive had isnt really a problem with the device, its more of a limitation. with the sensitivity tweaked you can get a good 2" or more from a penny. with a small hole that makes it hard to sometimes pinpoint which direction you should dig out because it will start beeping as soon as it gets close. so it could be down, right, left, etc. the only thing ive found to fix this was to back the sensitivity down little by little. it takes a few more seconds, but its saved a lot of time, and dirt.

what I would like to do is to modify the circuit to make the voltage variable according to how strong the signal is. ive tinkered around with it a little but haven't found the magic config yet. the idea is make the volume or vibe increase the closer you get to the object. if anyone has tried this and perfected it or has found a good starting point let me know.

I am not an electronics expert nor a circuit board expert but its been something that ive tinkered around with for 20 years or so. I am an engineer by trade so its in my nature to find tweaks and mods to make existing things better or more scalable. I would really love to get a solution to the variable volume/vibe issue. that would pretty much be the icing on the cake for the garrett fanboys. like I said earlier, I would love to have a garrett. but with 3 people in the household hooked on this hobby it just isnt feasible to spend that kind of money when a little bit of time and $25 would put out something almost as good.

thanks for reading. and sorry again about the old topic rez. but this was such an informative topic I thought it better to post here than starting a new one.

MC

 

[Leopard11]

Ive never heard that disableing the LED has increased the range. I dont need the LED so if it does that would be nice. The range on mine seems to fluctuate (always have to adjust the sens knob and a knob i attached to the inside pot so i can turn it without having to open the thing up. Anyone else notice range increase without LED powered?

 

[topdogintampa]

I hate resurrecting old threads but I thought I would weigh in on this because there were a few problems people had mentioned but didn't get answers to.

I bought my CT on a Saturday and within 30 minutes the switch was already messing up and you really couldn't tell whether it was on or off. so I put it away and classified it under useless junk and lesson learned. then I scanned the internet a bit and saw the switch mods and sensitivity mod so I decided to try it. I put in a new switch very similar to the old one but much better. spent a few minutes fine tuning the sensitivity. took it out and it worked like a charm. it was definitely worth the $16 for sure. would I rather have a garrett pp? YES! but I, like most people who buy these, just cannot justify that kind of money on a pp. especially if you are new to the hobby and really not sure if you'll still be interested in it a year from now.

that being said, for those worried about soldering the switch, there is no need to be worried. you don't even need any solder. all I did was heat up the solder iron and touch the point on the old switch where the wires are currently soldered. I moved the iron around and collected more than enough solder on the iron to use for the new switch. pushed the wires into the new switch and rubbed the iron around and it worked perfectly. no solder needed.

the sensitivity mod worked really well too. but don't be too hasty when you are doing this mod. most sites I went to basically said put your external knob to 1/2 then crank the internal pot until it just stops beeping and youre done. well I have found that this isn't always the case. when your PP is in the ground it can throw the sensitivity off by quite a bit. sometimes I have to turn the external knob nearly all the way down for it to stop beeping constantly over nothing. take a few minutes and try different settings on the external knob and internal pot. you'll find that you can really tune it in if you have time to work with it a little bit.

some other mods: I wired the vibe motor into the same wires as the speaker. it worked quite well. but after experimenting with it a little I found that it can increase the range quite a bit when the light isn't on. so I wired a switch to the speaker and the motor so I can toggle between the two, or have both. I also wired a switch to the LED so I can use it when I want (those last couple of digs on the way to the car right after sunset). its sometimes a hassle to carry around a flashlight. im already carrying 5 or 6 pieces of gear! so now I can get the range but I can also use the light if I want.

one other thing I did was tape up the hole covering the speaker. that helped out a lot with dirt and dust and sand getting in there. plus, I think the volume of the beep is way too loud. at one time I also covered the speaker with tape too.

mine also has problems every once in a while where it will beep constantly for no reason even after turning down the sensitivity. what I did was drill a small hole in the case on top of where the internal pot is. its normally covered with tape also but I can remove the piece of tape and turn down the internal pot and it fixes it. just remember to turn it back up. from my experience this happens when it gets very hot. I have read a forum where a guy wired a thermistor to his and he never has to adjust it even in extreme cold or hot weather. I haven't tried this but recently my wife and son have gotten the MD bug so chances are I will soon buy another centech and try this mod.

one of the other problems ive had isnt really a problem with the device, its more of a limitation. with the sensitivity tweaked you can get a good 2" or more from a penny. with a small hole that makes it hard to sometimes pinpoint which direction you should dig out because it will start beeping as soon as it gets close. so it could be down, right, left, etc. the only thing ive found to fix this was to back the sensitivity down little by little. it takes a few more seconds, but its saved a lot of time, and dirt.

what I would like to do is to modify the circuit to make the voltage variable according to how strong the signal is. ive tinkered around with it a little but haven't found the magic config yet. the idea is make the volume or vibe increase the closer you get to the object. if anyone has tried this and perfected it or has found a good starting point let me know.

I am not an electronics expert nor a circuit board expert but its been something that ive tinkered around with for 20 years or so. I am an engineer by trade so its in my nature to find tweaks and mods to make existing things better or more scalable. I would really love to get a solution to the variable volume/vibe issue. that would pretty much be the icing on the cake for the garrett fanboys. like I said earlier, I would love to have a garrett. but with 3 people in the household hooked on this hobby it just isnt feasible to spend that kind of money when a little bit of time and $25 would put out something almost as good.

thanks for reading. and sorry again about the old topic rez. but this was such an informative topic I thought it better to post here than starting a new one.

MC

Nice info MC and everyone else!

After reading all of the info in this thread with all of the mod's I am going to pick up a handfull of these this weekend and see if I can come up with the best mod overall. That circuit change as you get closer may be the only tough nut to crack but I'm going to see what I can come up with. I think if the range increases without the LED than that should be switchable also. Seems the heat from the hotter climates really affect this so the themistor angle sounds like the way to go. Possibly a speaker change for vol may be something to look into also. Looks like alot like the vibrating aspect also. I would guess to lower the prying eyes on the hole along with not having to remove headphones also. Easy enough....

Heck, when I'm done may have a fairly new redesigned unit..may just have to inject mold new cases in all the funky Ipod/Iphone/tablet protective case colors...lol! Now it comes in red, purple, or Nicki Minaj hot pink...

 

[cra61]

Ok, so half the posts here are bashing what has been done and how it has been done to the Centech. Let's take a look though at the toughness of the unit. It seems to be a workhorse, the Wrangler jeans if you will of the pointers. No one has said it is the prettiest, nor that it (many higher priced units are not) is waterproof, nor the best unit on the market, just that it works and well and you can do few things to it to make it last longer. This is the one I leave in my bag to make sure I have one every time I go out. It rides in the car, bumps, heat (no real cold here in Florida) and takes whatever abuse two teenage girls give to the bag when it is in their way. Summation: for the money a good unit and there are a few tips shown to make it last longer. Thank you Kimsdad for letting us in on your secrets to getting more than our moneys worth from the Centech.

 

[topdogintampa]

Just picked two of these PP's up at HF, did the button mod and the vibrating motor mod and they are working awesome!!! Took them out for a spin today and man what a difference it makes in recovery time!!! Can't beat the price of them with about $18 of mod's. It's rock solid now and the 100 Ohm NTC thermistor took care of the temp issue once and for all. Bought a 10 lot bag of them from eBay for only $2.50 shipped too.

Now all sealed with a switch to use buzzer/vib/both, internal sensitivity pot adjusted with external while in ground, tip dip sealed and I can put it in the fridge or lay it in direct sunlight without it going crazy. Thanls for all the info from everyone!

HH!

 

[topdogintampa]

Cen-tech PP was like a dream at the beach today in dry/wet sand and water! No issues at all even though it did cool off a bit here this morning but was up to 80+ by noon. Perfect day for hunting today.

If anyone needs the thermistor's I have 8 left and you can get them at Electronic Parts Online Store - Tayda Electronics $ .11 each

 

[mcockrell]

We have since bought two more of these and I honestly couldn't be happier with them. I've stuck it in mud, wet sand, clay. For $16 you can't beat it. Is it better than a garrett? No. But for 15% of the cost of a garrett I'll take it any day. We have 3 detectors so getting everyone a garrett would cost a small fortune. Other than changing pitch and volume according to proximity of the target it functions just as good as the garrett. That's a really awesome feature, but to me it isn't worth $100 for that feature.

 

[airscapes]

Whatever you do, DON'T try the TRX .. It is well worth $135 and yes I had a HF for a few months thinking that $130 for a pin pointer was just crazy stupid waste of money..

 

[topdogintampa]

Yes, I do agree, I don't need a $135 TRX now. Never have missed a target with the HF so it makes no sence. I will put the $100 to good use. Thanks and HH!

 

[mcockrell]

I also figured out to "supertune" these guys. It adds some reach. My air test had mine hitting dimes at 2". After the tune it hit dimes at 4" and quarters at almost 6"!!

The reason I tried this was to help narrow down the location of my target before I dig it up. Since most of the stuff I dig is 6" or less I'm hoping to be able to use this to just tap the ground around my target to get an indication of where I need to dig.

Obviously it wouldn't make any sense to use this in the hole in most situations as all you'll get is a ring as soon as you put the wand in.

Ok, yesterday we were out hunting and I was hunting near a cyclone type fence. I kept finding pieces of the fence. So I brought a few home. Got home and took my pliers and wrapped a small piece of the fence around the base of the wand. I wanted it snug, but still allow enough slack to be able to move it.

So turn your pp on and slide the wire wrapping up the shaft until the buzzer goes off. Then back it down just until it stops.

Voila! You just supertuned that baby! I have tried this around the house a lot and it works great. Have not field tested it yet. If you need to detune it just slide the wire ring back down the shaft. Easy easy.

Tomorrow I'm going to try it with some solder since its a little easier to mold and have it stay where I want it.

I'll post pics once I get it right and tested.

Thanks for looking
MC