BU-303 ! I have found the problem for all!

chuckctv · 02-21-2005, 05:56 PM

Well maybe for all...

I had one in my Car-PC for 6 months, then it started to wig ..(losing sats and stuff), so I finally assumed it was going bad, mind you it never messed up on me until resently, then i started getting all the problems you guys were getting. So when my new one came in , i decided to disect the old one. It has a tiny watch battery on it (assume to hold gps data or something), and i read the voltage on it-> IT WAS 2.3 volts. So i decided to open the new one ;(mind you i cut open the old one, to find THERE ARE SCREWS IN THE BOTTOM UNDER THE RUBBER BASE (x2 screws), remove them and it pops open. Anyway I checked the voltage on my new one and it was 3.5volts, unfortunatly the battery is soldered on. but i unsolder both batterys and switched them. GUESS WHAT!!!!!!!!!!!!!!!!!!!!!!!!!!

the new gps is acting up, and the old gps is working perfectly. So my assumption is that the battery voltage must be at or close to 3volts for the gps to work properly. ANd it is a normal watch battery. ALso im assuming again, some of you with malfunctioning units out of the box may just have a unit thats been sitting for a long time and the battery has become weak.

next test im going to do is try to use a resister and force feed from the usb power the 3volts into the line;(no battery attached though)... Ill let you know...

if anybody else has a BU-303 unit not working properly and have already replaced it, then give it a try (replaceing the watch battery inside and see if it works like new). If so please post it, this may help MANY_MANY BU-303 users...

chuck

Grayscale · 02-21-2005, 06:02 PM

Interesting, as I'm running my BU-303 without the watch battery hooked up at all

I ripped it off and have been too lazy to solder a new one on.

(the gps was acting up so I thought I could "reset" it by removing the battery...sure enough it fixed it)

chuckctv · 02-21-2005, 06:21 PM

SO removing the watch battery actually fixed your problem? HMMM! Possibly its set up to do more then keep rough lat/long data for faster sat-lock, maybe it holds other info also, and with out it, it does a complete restart when powered up? when you removed the battery and used your gps unit, did it take anylonger to acquire signals?

im trying to understand the unit and figure out if the battery is the problem only, because if just removing the battery fixes the problem ,then this kinda changes my view on its use in the gps...

chuck

Grayscale · 02-21-2005, 06:23 PM

I don't know what all data it holds with the battery being in, but I'm almost positive it keeps your last position so it gets a lock faster. I hadn't put the thing in my car when it was acting up. I was testing with my desktop computer, with it mounted on top of my canopy thing hanging off the roof

Anyways, it takes me like 30 seconds at least to lock =\, and it's probably because I don't have the battery in. How long does it take you to get a lock of at least 5 or 6 sats?

chuckctv · 02-21-2005, 06:50 PM

i just removed the battery now and tested it in my garage on the work bench. With out the battery in it locks on 3 sats with-in 20 secs, 4-5 @ around 40-60secs. (3 tests); not bad with the garage roof in place. im going to re-attach the semi-dead battery to try it out again. by the way, i just did a voltage test on the battery pins with the battery off, it seems to be a output of 2.75 volts (battery is rated at 3.3volts). new battery is outputing 3.5 volts (@time of opening box). and semi-dead battery is now reading out of the unit 1.9 volts.
im only throwing all this out thier incase others comeback one day to review these posts.

chuck

Opps forgot to hit (POST)!

Grayscale · 02-21-2005, 06:58 PM

Alright. Can you reattatch the good battery and tell how long it takes to lock as well? Thanks!

chuckctv · 02-21-2005, 07:08 PM

I just checked it out. with the bad batteryin unit, it took about 60 secs to lock on 3 sats, and apparently with me just being around the unit it seems to be loosing signal strength, but un hooking the battery it locks on to 4 sats roughly in half the time, and does not loose its signal with me around the unit.

* MY Theory.... (by Chuck Walker)

* when the units battery gets weak ( below 2 volts, only a true voltage due to capacitors on circiut can be made with battery unhooked)... It causes the circiut board voltage to drop, and then causes signal recieving problems. And so forth (i like saying that); you must either replace or remove battery for the unit to work, and as of yet their is no data to support that with the battery just being removed that thier is any problems occured from this action. All seems to work fine in either case.

Chuck

* Note: I still need more input from others if possible on trying these ideas out, it may just be my unit only, so to verify this theory others must try and hopefully suceed in my endevores...
thanx in advance.

chuckctv · 02-21-2005, 07:11 PM

unable to use good battery, its a mess to hook up gps in vehicle and after i played with it earlier i put the new one back to gether and placed in back in my truck (inside dash board). So i can now only play with the dead battery unit, i had planed on tommrrow going to radioshack and finding a tiny solderable battery to replace it with, or maybe a small watch battery holder to be able to replace the battery and attach it, their is actually quite abit of room in the black case.

chuck

ppgt94 · 02-21-2005, 07:41 PM

I'm very interested in this. I plan to perminently mount the BU-303 inside a new casing and onto the cars roof. I wondering if I should unsolder the battery or not?

sjwaldock · 02-21-2005, 07:42 PM

Just as a side line I have had a BC-307 do the same thing started to go funny after about six months will certainly check the battery if my BU-303 Dies

Grayscale · 02-21-2005, 07:44 PM

yep, there is. So Radioshack sells watch-sized batterys with leads or connectors to be soldered onto already? I think watch batteries are too slick or something to solder directly onto. I think I vaguely remeber trying to solder onto one. I should be looking for one that puts out 3.5 volts? I still have my battery I ripped off, and it even has part of the metal thing that is soldered onto it, so I may try to just resolder it. Yeah, just checked and I just have to resolder the metal pieces into the circuit board again.

You think the battery on there is going to help me get a faster lock? Hopefully you can get a battery to try it with at Radioshack, and let me know if I don't get a chance to test it out. In fact I know I won't since my screen needs a new VGA controller and is dead currently

EDIT: My post was intended to reply to chuckctv, didn't expect so many people to reply before me

chuckctv · 02-21-2005, 08:02 PM

you wont be able to solder onto a battery, you must either get a battery with leads on it, or mount a tiny battery holder in the unit. the imprinted voltage on the battery is 3.3volts. Also just incase anyone is interested- a battery metal material on the outside is not solderable, the leads you see on the battery if you look close at it arnt soldered but tac-welded on... I will find out tommorrow what is the best plan of action for a replacement battery, when i go to radioshack and see what they have on hand.

chuck

chuckctv · 02-21-2005, 08:07 PM

Also if anyone has opened up the gps unit yet, they will see the RS-232 unit and USB unit are the same. I viewed the circiut diagram on-line, it has a 3.3v battery and the wiring for both connections, also it has 2 larger solderable leads to wire up the battery next to the onbaord battery, their also labeled + & - ....

chuck

Grayscale · 02-21-2005, 08:26 PM

Can you link me to this circuit diagram plzkthnx

?

Scouse Monkey · 02-21-2005, 08:28 PM

You can solder to the battery but you normally have to rough up the surface 1st. The solder tags are welded on. I would get a battery with tabs on so you don't damage the cell keeping the iron on too long.

User Name		Remember Me?
Password