I have found a way to "adjust" the sensitivity of the TSU7500 pickup sensor (should work on a 7000 as well), and I’m wondering if there’s much interest in how to do it. If there is I will go to the trouble of taking some pictures and documenting what I did. Otherwise here it is in brief:

NOTE: this procedure DOES require opening the case of the remote (just four T-6 TORX screws), but DOES NOT require any soldering or other special skills. It should take about 15 minutes to complete and should pose very little risk of damage to the unit as long as you take reasonable care during the procedure.

The basic fix is to place a magnet of the correct strength against the pickup sensor so that the freedom of the little metal ball inside is attenuated. A weaker magnet provides less attenuation (and retains a higher sensitivity) and a stronger magnet provides more attenuation (and less sensitivity). I found that a magnet from one of those flashing LED pins was just right. Here’s a link to the kind of thing I’m talking about: [Link: glowproducts.com] you can see the two metal disk magnets stuck on the back of the pin (I only used one of the magnets). I attached the magnet in a non-permanent fashion so that I can remove it if I need to send the unit in for warranty work (my TSU7500 is only about four weeks old). You could just glue the magnet right to the pickup sensor if you want to, but you better be sure that you’re happy with the strength of your chosen magnet! If you use a metal type of magnet such as I did, make sure that you wrap it in some electrical tape so that if it should come loose or slip it won’t short out the circuit board (perhaps not a concern if you are gluing the magnet directly on). Also make sure that the battery is detached from the unit as long as the cover is off (for the same reason as above).

So there you are. I take no responsibility for any damages incurred. Attempt at your own risk, etc.

Since making this modification the unit no longer turns on when someone bumps the table etc., but does come on when I pick it up. Just what I want it to do!

Please post a reply if you are interested in a more detailed set of instructions. If I see a lot of interest I will make the effort, but otherwise the basic idea has been given above. Good luck.

Innovative!

Thanks for the information. I'm sure that a lot of TSU7500 owners would find it useful.

I assume that the noise that users complain about would still be an issue. Correct?

I would describe the noise as greatly reduced. It seems that as long as the "ball" can still move you will be able to hear it, so it really depends on how strong a magnet you use. Currently my remote only makes the little rattle noise when I give it a shake, but if I listen for it I can still occasionally hear the rattle during normal use.

I refer to the unit as having a "little metal ball", but I haven’t actually seen it so it could be something else inside the motion sensor component. My assumption is that they have used a small stainless steel ball since it is obviously only mildly attracted to the magnet.

CAUTION....

Although, "hey great idea".... any thinking of this mod should bare in mind the effects of magnetic fields on electronics. I have not seen a disassembled Pronto so this really is only a possibility not fact. However the magnets that apierre is suggesting are quite strong. One of basic rules of working circuit boards is not to use magnetic tools. The fields they produce when passing through any type of metal strip, (wire/circuit board trace) will induce a current into the strip. (A.K.A generator action)

Worse yet..... On board flash memory can be effected by magnetic fields. I not saying it will physically damage components, but can easily corrupt data being stored.

What I'm getting at is. If the magnet being used moves at all while installed, (movement would be necessary). There is the possibility that a current could be produced that may have negative effects. This might corrupt your installed pcf and firmware. I am not aware if the Pronto processor has any burnt root programming. Something that isn't effected by firmware updates. If there is, that could also be effected, and may not have a readily available fix.

Sorry... I don't mean to be so negative, but people should be aware of the possibilites before attempting this mod.

Best of Luck...!

I fully agree with smokinghot’s "CAUTION" that you could damage your remote by opening it up. You could drop it, have a static discharge, crack the case while prying it open, etc.

I do however think that the possibility of damaging the unit with a magnet is very low. Flash memory isn’t likely to be damaged by magnetic fields like the ones were dealing with here. Sandisk used to have a FAQ on their website stating that magnetic fields shouldn’t be a concern with flash memory. That FAQ seems to be gone now but a quick search did produce the following link: [Link: msn.pcworld.com] not exactly a definitive source I realize, but you get the idea. There are countless circuit designs using both flash memory and fairly powerful magnetic relays without any problems, and I have yet to see a flash manufactures data sheet that warns about exposure to magnetic fields. Actually there are very few electronic components that come with such a warning. Another example that comes to mind would be my cell phone: I keep it in a leather case which has a magnetic clasp very similar to the magnet I have used in this mod. The cell phone contains a wide variety of electronic components including flash memory. Every time I use the phone it gets dragged directly across this powerful magnet as leaves and enters the case without causing any damage to the electronics.

Please understand that I’m not claiming that it is safe to place a magnet inside your remote or any other piece of electronics. In fact there are some electronic components that certainly will be damaged by a magnetic field. I just wanted to offer a counter point to smokinghot’s prudent "CAUTION" (no sarcasm intended here).

Key words: "isn't likely", and "shouldn't"


Define powerful magnetic relays, and keep in mind "circuits designed". I work with board level circuitry, and have yet to see (by my definition) powerful relays used. Any switching that would need "powerful" relays would be done with SCR's. Here's a quick test on your magnet's strength. Take a terminal driver and hold it against a "fairly powerful board level relay" that is currently energised. Feel the amount of pull on the screw driver. Now do the same test with the magnet you're using or one like it. Notice the effort you have to use to pull it away as compared to the relay???


How many data sheets have you seen that state not to open the product's case and pour water on the circuitry???? Silly I know, but I hope you get the point I'm making. Data sheets aren't made to discribe what you can or cannot do with equipment or devices.


Open your cell phone case and you'll most likely see shielding within it.

For the record... apierre's mod in my opinion done properly wouldn't cause any problems. It's seems to be a fairly easy mod that from what I have read from people suffering from tilt sensor noise would be attempted within a moment of reading apierre's original post. However please don't take my warning lightly. In my line of work I need to examine the "worst case senario" when doing any modifications or new system development. This is what I'm stating here. My hats off to apierre for his ingenuity. Don't take my comments as attack on you abilities.

Absolutely no offence taken, and I agree with all points given. Further, if someone were to ask me if it was safe to place strong magnets against electronic circuits I would raise many of the same points and tell them that there is always a risk when electronics and magnetic fields are brought together.

In the end it just comes down to one of those risk vs. benefit decisions. I’m happy with the results, but another person could have a totally different outcome. Unfortunately it’s just not one of those things where anyone can say that this absolutely will be safe, there will always be some risk involved. Such is the nature of this type of modification.

I do want to thank you smokinghot for the points you have raised. People should be able to see as much information as possible before they decide to do something like this, and I certainly don’t want anyone blaming me if their results are different from mine! :-)

Maybe the best approach is to see how Apierre’s mod works for him over time. If the mod proves to be safe then Apeerre could post detailed instructions and pictures so that no one makes any mistakes. A big fat disclaimer may also be in order incase anybody follows the instructions and does mess it up.

As an EE (currently on the NASA JPL review board for Mars Science Laboratory motor controllers) that designs electronics for space applications (where magnetic fields and radiation are rampant) I can safely tell you, that without a doubt, the Pronto will have NO problem with those weak ceramic magnets. So work your mod with impunity.

I have circuits I designed running in close proximity to brushless DC motors with Neodymium magnets that are several thousand gauss each. My wife and I use reject motor magnets on the refrigerator. A 3/4" neo magnet will hold well over a 1/2" of paper. If it attached directly to the refrig, you cannot pull it off. It has to be slid over an edge and pried off.

As for flash memory, it is immune from issues with reasonable magnetic fields. Older "magnetic" ROMs theoretically could be susceptible to a weak magnet.

Getting back to electronics in general, when I was designing military electronics, one had to design with "effective loop area" of circuit traces on PC boards in mind so they would be hard to damage with an EMP or a nuclear event. While there is certainly credence to the statement that magnets in close proximity to circuit card wires will induce a voltage (basic physics), the effect is negligable with the high density PC boards with ground planes that are used today. Furthermore, the magnetic field must be moving. A statically mounted magnet does not meet that criteria.

It would take a magnetic field of immense magnitude to hurt the Pronto.

As a goof, one day a coworker and I tried to break a cellular phone (that he wanted to get rid of) by placing it in a 50 ampere toroidal degaussing coil. The phone bounced around inside the coil all by itself, and got physically warm due to eddy currents, but still worked after several minutes in the field. In case anyone is curious, it was a Motorola.

Well then..... I stand corrected...:)

The basis of my comments were drawn from the generator action theory. In defence of my posts...I did say "If the magnet being used moves at all while installed, (movement would be necessary)." So there....at least I'm a little right......HA

jgedde, I bow to your wisdom. Although I was fully aware of the possible induced voltage caused by the traces of the board cutting the lines of magnetic force. The magnitude of that induced voltage simply can't be determined with accuracy. Furthermore I'm not an authority on the robustness(?) of IC's. So, I sound the bell warning people of the possibility of side affects.

Thank you for chiming in. I'm sure you have made some people very happy with your expertise.

Actually smokinghot, I’m still very glad you raised your points. To be honest I had a little niggle of concern regarding the magnet even before you posted. If you hadn’t commented we would never have seen jgedde’s post and I would still be wondering about this.


So far other than our dialog it doesn’t look like interest is that high anyway.

I would have to disagree. This thread has been viewed 166 times so far. Not everybody comments.

Are some Prontos over-sensitive to pickup hence the need for the mod? Mine has the opposite problem. It doesn't always detect motion when I pick it up.... I wish it would come to life a bit easier.

That's the beginning of the conversation jgedde. The motion sensor in the 7500 was designed to be more sensitive. The by product of the adjustment done by Philips caused the overly loud noise the 7500 makes. this is an approvement by most peoples standards. The 7000's motion sensor can't be adjusted.... sorry