Smoking PING :)))))

DutchBot

Something really wild happend last night. I had my robot with the robot control board and 3 ping sensors set up fine. It roamed the house and things where great. Last couple of days I was a bit busy so the bot just sat on a shelve. Last night I got a friend of mine comming over that wanted to see the Bot. So I put it on the floor and switched it on. Nothing happend, power led went on, ping leds went on and next smoke came out me left and right ping sensor!

I checked everythig but al seems fine. It just has the 3 pings connected and 2 motors all hooked up in the right way.

Anyone a clue why my robot control board is starting to fry ping sensors? Will be this be warranty? Did anyone ever encounter something like that?

allanlane5

How unusual. Could the batteries have been put in backwards? Was the jumper put in "Vin" position -- because I'm pretty sure the Ping sensors want ONLY 5 volts.

dandreae

Are you able to program the BASIC Stamp?· If so, check the I/O pin that the Ping was on and see if it still works.· Send me an e-mail at support@parallax.com (attenion Dave) and well see what we can do to get you up and running again.

Dave





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Dave Andreae

Parallax Tech Support·

rpdb

Is this a MSR1 board? If so, check the 5v and 3.3v at the female headers next to the motor connectors with a meter. If the voltages are not close the voltage regulator on the board might be bad.

DutchBot

I think the MRS1·board died on me. I'm getting 0 volts on the 3.3 and 5v your talking about and a constant 2.16v on all of the +/- connectors where the servo's and sensors go in. Prop chip can neither be found, it senses the usb device being connected but that's about it. Don't think the pings survived neither, chips are toast.

Send you a mail Dave.

DutchBot

Took everything appart last night and checked every single wire and component but noting seems to shortcut. I'm completely mystified as to what could of caused it. Is there any chance that the MRS1 just blew up on me? Checked the board also but can't see anything fried on there (it's not working properly·anymore, but no damage can be seen). Some expensive hickup this was....... It's been 1 step forward 3 steps back all the way so far but I'm still having fun [noparse];)[/noparse]

What I think is strange (well, maybe im not seeing things right) is that both sensors and board are gone. I would imagine that a shorcut would·kill one of them. In this case I saw the left and right sensor go up in smoke but the center one didn't. Even if it was overvolting the sensorports why on only 2 instead of 3 and why did the mrs1 board blow up? That should be able to handle up to 24 volts and I'm running it on 11.1. I'm 100% sure that nothing touched the board (as it sits on the middle deck and is protected by wood).

allanlane5

Then it sounds like a voltage regulator failure, letting 11 volts in on the Vss line -- that'll do the job everywhere.

DutchBot

How do these voltage regulators actually work? Is it like a static thing that just outputs steady voltage or is it like a switchable thing that adapts to the voltage? I wondered because there is one thing that I did do before it went on the shelve, i hooked it up to a 9 volt battery just to see how the motor would perform with a lower voltage (they run between 4 and 12 volts). Could it get confused due to different voltages?

Mike Green

The MRS1 uses a switching regulator that should work on any supply voltage from 6.5 to 15V. If you hooked up the 9V battery backwards, you might have damaged things. Some voltage regulators have protection circuitry built-in to prevent damage to the 5V and/or 3.3V circuitry if you connect the power supply backwards. Other voltage regulators don't have this. There are some other ICs on the MSR1 that are connected directly to the supply voltage and they can be damaged by connecting the supply voltage backwards.

allanlane5

A "Linear Regulator" like those used on the BoardOfEducation and the BS2 itself act like a variable resistor, dropping enough voltage to keep their output at 5 volts, no matter what current (within limits) you pull through it. A "switching regulator" is quite a bit more complicated -- with a local oscillator to convert the incoming DC to AC, then convert that AC to a lower voltage, then convert that lower voltage AC to the desired DC. This can be done with a LOT more efficiency than a "linear regulator" (which converts the excess voltage to heat), but is quite a bit more complicated.

I've had small switching regulators fail 'shorted', putting the full input DC on the 5 volt line, which can destroy a lot of chips. I've NEVER had a "linear regulator" fail shorted -- but this is just my experience.

DutchBot

I'm using the tamiya connectors on al my battery packs so you can't really hook them up in reverse (the holes don't match) so I can exclude that reason I think. Reading the above its starting to look that the regulator failed for some reason.

rpdb

The MSR1 uses an Linear Technologies LT3501· Monolithic Dual Tracking 3A Step-Down Switching Regulator for 5.0v and 3.3v supply. Here is the data sheet and the schematic of the MSR1. If one component ie the voltage divider resistors connected to fb1 or fb2 opens, the regulator will loose regulation and output Vin consequently causing a large leak of the factory installed SMOKE from some other components.

They have a special machine at Parallax called the RMA that can re-inject "factory fresh SMOKE" back into the leaking devices. They·fix the leaks and send them back to you.·Give tech support a call and they will give·you the details.

Tech support at Parallax has always been·super great·any·time I have had a problem. I once had both "SMOKE" and "Flames" leak from a MSR1 board Prop chip, and the RMA machine re-installed both, it is still working today!!!

Sal Ammoniac

Here's a video that describes how linear and switching regulators work: www.eevblog.com/2010/05/29/eevblog-90-linear-and-ldo-regulators-and-switch-mode-power-supply-tutorial/