View Full Version : Homework board will not power on

04-02-2010, 10:10 AM
I have a basic stamp homework board and after entering the END command, it for some reason refuses to power on. I've tried half a dozen batteries and connected it directly to a variable wall transformer and all I can get out of it is a brief flicker of the run LED when I press reset. The board will not communicate with the computer either, a problem I had immediately before the board shut down. Any ideas? I was controlling two small 6v DC motors and everything was going fine (once I got the board up and running) until I got tired of the whirring gears and stopped it...

Mike Green
04-02-2010, 10:27 AM
You didn't give details about what you had been doing with the two 6V motors. That's what I think of to explain why it doesn't work now. There's nothing special about the END command that could possibly prevent the board from communicating with the computer. The Stamp Editor forces the Stamp into reset to identify or download a new program to it. That would prevent any existing program from running.

It's possible something has happened with the connection between the Homework Board and the PC. Make sure you get +5V across Vdd/Vss. The Stamp has to be powered and running (then reset) for it to communicate with the PC.

04-02-2010, 11:19 AM
I was just turning motors on and off. DO, HIGH and LOW. Nothing fancy. Is there any reason the board or my computer may now be rejecting the radio shack usb-serial cable? It says it has the driver, but something obviously isn't right.
From the command pin to Vss, each motor will remain on continuously and from Vdd to Vss I'm reading 6.3-6.5v. Could it be stuck in a loop? Maybe something has shorted on the board?

04-02-2010, 11:43 AM
Research tells me I bought a lame duck with the RS serial to USB (it's odd that it worked fine for several weeks and now it decides to die...) but that doesn't explain the status light not coming on or the stamp not running programs/resetting, does it?

PJ Allen
04-02-2010, 09:23 PM
Running motors on/with an HWB, suspect that your HWB's battery is exhausted.

Mike Green
04-02-2010, 10:08 PM
Vdd to Vss should read 5V. Vin to Vss should read whatever you're using for a power source. If Vdd to Vss is 6.3 to 6.5V, something's very wrong, anything from a short somewhere on the Homework Board to a broken voltage regulator.

04-02-2010, 11:32 PM
Check temperature on voltage regulator. If you have 6,5V Vdd to Vds you·have turned regulator in<->out (not in this - homework board is factory manafactured), or you have·interupted GND on regulator.·Yes. maybe you have·broken regulator.


Every problem·have at least one·nice, simply and·wrong solution.

Post Edited (C-Bob) : 4/2/2010 4:52:09 PM GMT

04-03-2010, 06:19 AM

It sounds like there might be some readings (voltages) that you shouldn't be getting on your HWB; if you would like to have the HomeWork Board tested, please contact Technical Support to set up an RMA. You can use the following number to contact us; also if you can have your customer number with you when you call, just makes the process that much easier.

·Parallax Technical Support : 888-997-8267


Joshua Donelson
www.parallax.com (http://www.parallax.com)