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WARNING!! StingRay/MRS1 3.3V No regulation? Help Me Test Please Reply — Parallax Forums

WARNING!! StingRay/MRS1 3.3V No regulation? Help Me Test Please Reply

rpdbrpdb Posts: 101
edited 2010-02-15 09:31 in Robotics
After hours of looking at my code, I decided to check voltages, at Vin above approx 9.0V the program quit, and have found I believe a serious problem.

I have a MRS1 board on my test bench fed by a high quality variable power supply. I am measuring the voltages at the 3.3, 5.0 and Vin female headers at the front of the board (as well as the jumper holes·at the translators).· I have nothing connected to the I/O headers or H-bridge.

Vin follows very close to the power supply 7.2-12V, V5.0 is well regulated and stays at about 4.95V with pwr supply varied 7.2-12V, however,·at the 3.3 female header (and other points) I am getting 3.87 - 6.06V as I varied the power supply 7-12V!!!!! No regulation...

Does anyone have the ability to test their board at the 3.3V header·with an adjustable power supply·from 7.2 - 12V, so I may compare. I tried Power to both the co-axial and molex Vin points as well with no difference (the schematic shows them as the same).

Please, Help me Obi Wan...You're my only hope..

Comments

  • WhitWhit Posts: 4,191
    edited 2010-02-12 15:03
    rpdb said...

    Please, Help me Obi Wan...You're my only hope..
    rpdb,

    It sounds like you do have some sort of problem. However, Obi Wan is not your only hope. Parallax Tech support is excellent and will help get you free from the dark side. Give them a call and may the force be with you!

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    Whit+


    "We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney
  • CannibalRoboticsCannibalRobotics Posts: 535
    edited 2010-02-12 15:33
    On my StingRay, I measured my 3.3V and 5V headers with a variable supply. They stayed rock steady on the Fluke at 3.30 and 4.99 volts with supply voltages ranging from·5.3 to 15 volts. The 5 started dropping off around·5.3 volts and the 3.30 around 5.6 volts.

    Sounds like you do in fact have a problem.

    Jim-



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  • DufferDuffer Posts: 374
    edited 2010-02-12 16:47
    Mine was rock steady also. 4.98 and 3.29 respectively at input voltages of 7.5V, 9V and 12V from a switching power supply and the same outputs when using a 7.2V NiMH measured at 7.79V for input.

    Duffer

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  • mugurmugur Posts: 105
    edited 2010-02-12 21:35
    rpbd, this might sound stupid from my part, but... are you measuring against GND?
    or between the 2 pins of that 5V and 3.3V headers? Before that, everything worked fine? I had a failing MSR1 as well, and it was replaced.
  • rpdbrpdb Posts: 101
    edited 2010-02-13 01:42
    Thank you guys so much for checking, I really appreciate it. I remember the old IBM PC power switching supplies would give strange readings without a load resistor attached, so I thought I might be missing something along those lines.

    I am so lucky to be just a little less than an hour away from Parallax, so I drove down and met with Dave at tech support. PARALLAX SERVICE AND SUPPORT IS SECOND TO NONE!!! IMHO and experiance. We tested again and now the 3.3 was good but the 5.0 varied on 12v battery supply, and then the 3.3 varied on a bench supply. In the end I got a new MRS1 board.

    Thanks for your help Dave, good talking with you Joshua.

    I then went to the sales and bought a gyro, cables and temp sensors that I want to put on my HB25s to switch the fans only when necessary and another MRS1 board. The whole crew at Parallax are so helpful. They even gave me a couple of band-aids (Propeller Hat stickers) just to make me feel better. What a difference to work with people that care about the customer.

    Anyway, thanks again for checking and helping me form a conclusion. My bot might be mobile tonight.

    rpdb

    BTW the reason I said "warning" is to alert others so they might test and·would not ruin anything with 6.0 volts applied to a 3.3 volt device. GND is the mounting holes or black I/O pins.

    Post Edited (rpdb) : 2/13/2010 2:07:10 AM GMT
  • WhitWhit Posts: 4,191
    edited 2010-02-13 02:37
    rpdb,

    Glad you've got your problem resolved. Wish I could just drive over to Parallax!

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    Whit+


    "We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney
  • Tony B.Tony B. Posts: 356
    edited 2010-02-13 03:54
    Glad your up and running. I too think Parallax'a customer service is second to none.

    Maybe I should check my boards. The one on my plywood stingray seems to be working correctly.

    Tony
  • FranklinFranklin Posts: 4,747
    edited 2010-02-13 04:21
    Whit, if you could drive over to Parallax nobody would ever hear from you again. (can you say broke and homeless?)

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  • rpdbrpdb Posts: 101
    edited 2010-02-13 05:19
    Yes TBill,

    Good idea to check the voltages on this board as it is an early release, I would hate to see some one leak the factory installed smoke from a sensor.

    Oh, Whit....don't bother driving there, I already bought everything at the store, shelves are empty now [noparse];)[/noparse]
  • WhitWhit Posts: 4,191
    edited 2010-02-13 05:22
    Franklin said...
    Whit, if you could drive over to Parallax nobody would ever hear from you again. (can you say broke and homeless?)
    You are probably right... The truth hurts. smile.gif

    Thank goodness rbdb bought them out.

    There is free shipping on web order this weekend though...

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    Whit+


    "We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney
  • CannibalRoboticsCannibalRobotics Posts: 535
    edited 2010-02-14 15:12
    Hey!
    We just learned something important. rpdp has a sideline business now running over to Parallax for us?

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  • rpdbrpdb Posts: 101
    edited 2010-02-14 18:32
    Sure, for a phenominal fee of course.

    Please see the thread I started about Fire and smoke.
  • wyzard28wyzard28 Posts: 24
    edited 2010-02-15 09:31
    I had the same problem, I believe. I had finished the assembly of my new Stingray and was testing the motors with the motor test program. I had a response from each motor (as expected) and as it was getting late, I popped off to bed after shutting everything down. The next morning, I was about to resume testing and ... Dead board. The Propeller tool couldn't locate the chip. Sadly, living in Tulsa, I was unable to pop down to the shop (like SOME geographically less-challanged people I know of) but Parallax sent me off a replacement board overnight and I haven't had any trouble with the new board since (knock on my next robot's CNC'd plywood chassis--thanks, Chip!). Although I didn't see or smell smoke, I'll bet that's what happened to me too; I shut things down before the fire & brimstone phase. A bad bunch of 3v3 regulators?
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