Professional Development Board's Pulse Generator Hot to touch
knightofoldcode
Posts: 233
Board,
I purchased my PDB a few years ago, and it's mostly been in storage (haven't had time to do what I've wanted to, projects got on hold.) Now that I have a little bit of time, I've started playing around again. During storage, I couldn't find my wal wart that came with the board, so I used a universal from Radio Shack (universal voltage, I put it at 12V) only problem is that the amperage is too low, (300MA according to the wall wart) so the power LED came on for a second, then turned off, and continued to cycle for a second between each on/off. So I turned the wall wart down to a lower voltage, 9V, it now functioned correctly, and I started to play... programmed a BS2... Played a little with the LCD. After a few minutes I noticed that the Pulse Generator was getting hot....very hot. I immediately turned off the power supply, and have yet to figure out why it's gettign so hot. I have removed all socketed IC's, all jumpers, all wires, BS2, etc. No change. When powered from barrel jack the Pulse Generator gets hot (too hot to touch) within 1-2 seconds. I tried powering it with a 5V on VSS and VDD, same results. But again, everything else works perfectly!
I read previous posts about incorrect polarity... I have not done that. Nor have I ever hooked up a servo to this board. I don't think I've ever used the VIN either.
Also the 1K LED is illuminated permanently, when I press the button it dims until the button is released, but it never changes frequency. I seem to recall it defaults to 1 Hz frequency normally.
When running via VSS/VDD 5V (well regulated), it is right at .50 amps current being drawn/consumed without the BS2, but all other IC's present. 2.5 watts seems a little excessive?
No other IC appears to get hot. I connected power, waited until the Pulse Generator was hot, then I felt all other IC's and nothing else appears to get hot. I havn't tried letting it have power for more then about 15 seconds, so it may get hot after a while, but I would assume if they were having problems also, that they would get hot just as fast as the pulse generator.
My board is a PDB Revision B 2005, with USB built on board.
I am stumped. I can't figure it out. Any ideas? Or anything I should try/test/check?
Much thanks,
Knightofoldcode.
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I purchased my PDB a few years ago, and it's mostly been in storage (haven't had time to do what I've wanted to, projects got on hold.) Now that I have a little bit of time, I've started playing around again. During storage, I couldn't find my wal wart that came with the board, so I used a universal from Radio Shack (universal voltage, I put it at 12V) only problem is that the amperage is too low, (300MA according to the wall wart) so the power LED came on for a second, then turned off, and continued to cycle for a second between each on/off. So I turned the wall wart down to a lower voltage, 9V, it now functioned correctly, and I started to play... programmed a BS2... Played a little with the LCD. After a few minutes I noticed that the Pulse Generator was getting hot....very hot. I immediately turned off the power supply, and have yet to figure out why it's gettign so hot. I have removed all socketed IC's, all jumpers, all wires, BS2, etc. No change. When powered from barrel jack the Pulse Generator gets hot (too hot to touch) within 1-2 seconds. I tried powering it with a 5V on VSS and VDD, same results. But again, everything else works perfectly!
I read previous posts about incorrect polarity... I have not done that. Nor have I ever hooked up a servo to this board. I don't think I've ever used the VIN either.
Also the 1K LED is illuminated permanently, when I press the button it dims until the button is released, but it never changes frequency. I seem to recall it defaults to 1 Hz frequency normally.
When running via VSS/VDD 5V (well regulated), it is right at .50 amps current being drawn/consumed without the BS2, but all other IC's present. 2.5 watts seems a little excessive?
No other IC appears to get hot. I connected power, waited until the Pulse Generator was hot, then I felt all other IC's and nothing else appears to get hot. I havn't tried letting it have power for more then about 15 seconds, so it may get hot after a while, but I would assume if they were having problems also, that they would get hot just as fast as the pulse generator.
My board is a PDB Revision B 2005, with USB built on board.
I am stumped. I can't figure it out. Any ideas? Or anything I should try/test/check?
Much thanks,
Knightofoldcode.
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Gravity doesn't exist. The Earth sucks.
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Make a man a fire, and he will be warm for the night.
Light the man on fire, and he will be warm for the rest of his life.
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Comments
There's not much to the pulse generator, just a PIC microprocessor, some LEDs, and a pushbutton. You might check for short circuits in the
area of the pulse generator, but most likely the PIC is somehow damaged.
Post Edited (Mike Green) : 4/12/2009 1:59:37 PM GMT
Thank you for your reply. I agree that it's most likely a damaged pulse generator. But 1) How?.... I don't think I've done anything that could destroy it. 2) I don't care much about it.... so is there any harm in not getting it repaired? IE, I just de-solder the chip myself, and leave it at that.... if I do that, what can I check to make sure nothing else is going to get damaged further down the road......
I'm still of course interested in anyone else's opinions.
Knight.
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2) The problem in just removing the chip is that you still wouldn't know what happened. I'd still talk to Parallax Tech Support.
Knight.
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I only had a BS2 and and SX installed (I think, I may have had the logic analyzer module installed also). The SX wasn't running and the BS2 was running a very simple program and not supplying power to anything with it's pins.
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- Rick
Much thanks for that information. The .5amps @ 5VDC that I measured was with NO basic stamp, all IC's removed (Audio Amplifier, 4CH Driver, Basic Stamp, SX28, etc). So as you say, it's certainly excessive. Thank you.
Knight.
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I have had some problems with the PULSE GENERATOR on My Pro.Dev.Boards.(All self inflicted) I zapped the first one(pulse gen.),I sent it to Parallax and they fixed it/replaced it in a super fast (NASCAR style pit stop) turn around. I zapped the next one about 8 months later. While the bad "ZAPPED" PULSE GENERATOR had no affect on the $BS2 series of stamps, it did effect the SX28. It killed its performance. I have to use the SX28 on a generic bread board.
Maybe this will lead to a harder to blow fix for the PULSE GEN. circuit !
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I sent it to Parallax...we'll see. As far as I am concerned, if they want to remove the IC all together, I think that would be fine with me.... just don't bother with a pulse generator. Maybe put it on a daughter board. What I would like to see is the IC be socketed!.... That way it's removed 90% of the time, except when I am using it... Or, put in a power switch to it....remove all 5V to it, unless you are using it.
Knight.
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-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=-=-=-=-=-=-=-=-=-=-=-
This message transmitted with 100% recycled electrons.
-=-=-=-=-=-
Gravity doesn't exist. The Earth sucks.
-=-=-=-=-=-
Make a man a fire, and he will be warm for the night.
Light the man on fire, and he will be warm for the rest of his life.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=-=-=-=-=-=-=-=-=-=-=-