Finding a short on the CORE

[dubphil]

Hello,

I don't own a sophisticated multimeter with the beep beep feature to detect shorts, so I have stolen in my kids bedroom an awful toy that gives an horrible sound when you press a button, yeah that will do the trick ;)

After having replaced the toy's button by two wires, I decided to try it on my finally buggy CORE (you can read the story here : ) . So I clamped the anode wire to the ground and used the cathode wire to make the contact on the solder joints; the result was a hurly-burly nearly everytime I made the contact to a joint. So I opened the .brd file of the CORE and drawn "in black" all the tracks and joints that are directly connected to the ground then I drawn all the tracks and joints that are connected to the ground with a composant (capacitor, resistor, etc). So finally it remains few joints and tracks to check.

here is the scheme : http://migratis.net/find_short.png

knowing that my problem is that I measure +5V before the R9 resistor and just after I measure 3,8V, the beep beep trick doesn't help much : around this place, everything beeps...

pfiouuuuuuu electronic is the most hard discipline to learn by myself.

Thanks to teach me what I can't find by myself.

Best regards

Philippe

[jbartee]

Hello,

I don't own a sophisticated multimeter with the beep beep feature to detect shorts, so I have stolen in my kids bedroom an awful toy that gives an horrible sound when you press a button, yeah that will do the trick ;)

After having replaced the toy's button by two wires, I decided to try it on my finally buggy CORE (you can read the story here : ) . So I clamped the anode wire to the ground and used the cathode wire to make the contact on the solder joints; the result was a hurly-burly nearly everytime I made the contact to a joint. So I opened the .brd file of the CORE and drawn "in black" all the tracks and joints that are directly connected to the ground then I drawn all the tracks and joints that are connected to the ground with a composant (capacitor, resistor, etc). So finally it remains few joints and tracks to check.

here is the scheme : http://migratis.net/find_short.png

knowing that my problem is that I measure +5V before the R9 resistor and just after I measure 3,8V, the beep beep trick doesn't help much : around this place, everything beeps...

pfiouuuuuuu electronic is the most hard discipline to learn by myself.

Thanks to teach me what I can't find by myself.

Best regards

Philippe

While in principle using a sound producing toy to test continuity might work, it really isn't a good idea and I definitely wouldn't rely on it (although it's a clever idea!). Just buy yourself a decent multimeter -they're not that expensive. You're multimeter probably already checks for continuity anyway, even if it doesn't have a beeping function. This just means you'll have to keep one eye on the multimeter display when doing continuity checks.

[dubphil]

This just means you'll have to keep one eye on the multimeter display when doing continuity checks.

My cheap multimeter has an ohmmeter scaled to 1K, do I need to use this to test the continuity ? If yes, measuring the resistance at each point against the ground is the correct checks to do ?

Best regards

Philippe

[rosch]

yes, any ohms value will do (continuity=0 ohms, no continuity= infinite resistance)

and it's not necessarily done between a point and ground, it's connectivity between two points in general.

edit: the word continuity

Edited February 23, 2010 by rosch

[technobreath]

I have had several multimeters in all price ranges and i have never seen one wo the beeping function, strange...

I just bought a fluke for my job, and it turned out to limit on 1k wich was bad, because i need to measure in the range from 0 to 10k as i work with alarmsystems. Big misstake, so if u buy a new multimeter then make sure it does what u need hehe. I discovered this after writing my name all over it, so no chance of returning it hehe, and it wasnt cheap! About 100 euros.

[nILS]

I have never owned a multimeter that cost more than 12eur. All of them beeped. All of them measured up to 2MOhms. All of them worked until I lost them :)

[ilmenator]

I kind of stick out :frantics: - my multimeter does not beep! A good old Voltcraft DM 301 (Conrad?). At least twenty years old!