element14 Community
element14 Community
    Register Log In
  • Site
  • Search
  • Log In Register
  • About Us
  • Community Hub
    Community Hub
    • What's New on element14
    • Feedback and Support
    • Benefits of Membership
    • Personal Blogs
    • Members Area
    • Achievement Levels
  • Learn
    Learn
    • Ask an Expert
    • eBooks
    • element14 presents
    • Learning Center
    • Tech Spotlight
    • STEM Academy
    • Webinars, Training and Events
    • Learning Groups
  • Technologies
    Technologies
    • 3D Printing
    • FPGA
    • Industrial Automation
    • Internet of Things
    • Power & Energy
    • Sensors
    • Technology Groups
  • Challenges & Projects
    Challenges & Projects
    • Design Challenges
    • element14 presents Projects
    • Project14
    • Arduino Projects
    • Raspberry Pi Projects
    • Project Groups
  • Products
    Products
    • Arduino
    • Avnet Boards Community
    • Dev Tools
    • Manufacturers
    • Multicomp Pro
    • Product Groups
    • Raspberry Pi
    • RoadTests & Reviews
  • Store
    Store
    • Visit Your Store
    • Choose another store...
      • Europe
      •  Austria (German)
      •  Belgium (Dutch, French)
      •  Bulgaria (Bulgarian)
      •  Czech Republic (Czech)
      •  Denmark (Danish)
      •  Estonia (Estonian)
      •  Finland (Finnish)
      •  France (French)
      •  Germany (German)
      •  Hungary (Hungarian)
      •  Ireland
      •  Israel
      •  Italy (Italian)
      •  Latvia (Latvian)
      •  
      •  Lithuania (Lithuanian)
      •  Netherlands (Dutch)
      •  Norway (Norwegian)
      •  Poland (Polish)
      •  Portugal (Portuguese)
      •  Romania (Romanian)
      •  Russia (Russian)
      •  Slovakia (Slovak)
      •  Slovenia (Slovenian)
      •  Spain (Spanish)
      •  Sweden (Swedish)
      •  Switzerland(German, French)
      •  Turkey (Turkish)
      •  United Kingdom
      • Asia Pacific
      •  Australia
      •  China
      •  Hong Kong
      •  India
      •  Korea (Korean)
      •  Malaysia
      •  New Zealand
      •  Philippines
      •  Singapore
      •  Taiwan
      •  Thailand (Thai)
      • Americas
      •  Brazil (Portuguese)
      •  Canada
      •  Mexico (Spanish)
      •  United States
      Can't find the country/region you're looking for? Visit our export site or find a local distributor.
  • Translate
  • Profile
  • Settings
Raspberry Pi
  • Products
  • More
Raspberry Pi
Raspberry Pi Forum Raspberry Pi Fuse - Have you ever tripped it?
  • Blog
  • Forum
  • Documents
  • Quiz
  • Events
  • Polls
  • Files
  • Members
  • Mentions
  • Sub-Groups
  • Tags
  • More
  • Cancel
  • New
Join Raspberry Pi to participate - click to join for free!
Featured Articles
Announcing Pi
Technical Specifications
Raspberry Pi FAQs
Win a Pi
Raspberry Pi Wishlist
Actions
  • Share
  • More
  • Cancel
Forum Thread Details
  • Replies 4 replies
  • Subscribers 662 subscribers
  • Views 8775 views
  • Users 0 members are here
  • fuse
  • raspberry_pi
  • raspberry pi
Related

Raspberry Pi Fuse - Have you ever tripped it?

Sean_Miller
Sean_Miller over 4 years ago

I got a little sloppy and threw a spark on my Raspberry pi.

 

After, the SD card light shows no sign of life and the SPI Display somewhat flickers.  It never boots.

 

Google quickly showed that the fuse is self healing over what could be minutes, hours, or even days.

 

So, my question is - anyone ever trip their fuse?  How long did it take to function again?

 

-Sean

  • Sign in to reply
  • Cancel
  • mp2100
    mp2100 over 4 years ago

    I will admit to shorting the 3.3v pin to ground on the header.  It was a while ago, a Pi 3, and it never came back. image   I'm hoping you have better luck.

    • Cancel
    • Vote Up +1 Vote Down
    • Sign in to reply
    • Cancel
  • Gough Lui
    Gough Lui over 4 years ago

    The self healing properties of the polyfuse normally doesn't take all that long to at least get back to a functional state. When it trips, it gets warm and needs to cool down to restore its original resistance, but even without a full restoration it should still be okay to boot again in a relatively short period (minutes) assuming your downstream load is not high (i.e. attached bus-powered USB peripherals). Depending on where/how the spark came about, you could have done some permanent damage - rail to rail (e.g. 5V to 3.3V) are known to be likely to be disastrous.

     

    The polyfuse does have some headroom to allow for some USB downstream loads - so if after the event, it still won't boot with minimal/no downstream loads, you may well have a dead Pi. To confirm, you could (at your own risk) power through the GPIO pins from a capable lab supply which would bypass the polyfuse altogether, or as I've done with some of my Pis, remove and short over the polyfuse connection altogether (mainly so as to power heavier downstream loads in my instance).

     

    But perhaps also worth preparing a known good mSD card to test with as sometimes improper powerdown can lead to unbootable cards ...

     

    - Gough

    • Cancel
    • Vote Up +2 Vote Down
    • Sign in to reply
    • Cancel
  • gam3t3ch
    gam3t3ch over 4 years ago

    I would test the polyfuse first make sure it wasn't the issue if it is one thing you could do is replace it or just bridge it if you really wanted but I don't recommend. 

     

    you should be reading 5 volts on both sides with a small drop on the one side this is normal.  I just tested as well since I had one on my bench it is a 267T one which is 2.6amp from what I came to understand.

     

    For a dollar for the part it might be worth finding a replacement 2.6amp polyfuse.  I am going to say its probably a max 6v as well.

     

    and it could be late and I am just talking out loud again? lol

    • Cancel
    • Vote Up +2 Vote Down
    • Sign in to reply
    • Cancel
  • Sean_Miller
    Sean_Miller over 4 years ago in reply to gam3t3ch

    Gave it a day and no luck.

     

    I actually think I zapped outside of the poly fuse.  Looking at the schematic, it appears the polyfuse is off the USB power in.   I was powering with the 5V pin.

     

    However, I think I actually zapped it by putting 16V through the headphone jacks ground .  :-)

     

    I was trying to get the hum out of an LM386 amplifier circuit and thought I'd power it from as close to the battery as possible to see if that made a different. 

     

    Boy did it!  No more hum, that's for sure.

     

    Oddly, when I put the 5V rail on the O-scope, it cycles between 3.3 and ~5Vs consitently.  In turn it cycles 600mA and 400 mA just sitting there dead with a red LED.

     

    Would be interesting to fix, I guess, after I get my project back together with another PI.

    • Cancel
    • Vote Up +2 Vote Down
    • Sign in to reply
    • Cancel
element14 Community

element14 is the first online community specifically for engineers. Connect with your peers and get expert answers to your questions.

  • Members
  • Learn
  • Technologies
  • Challenges & Projects
  • Products
  • Store
  • About Us
  • Feedback & Support
  • FAQs
  • Terms of Use
  • Privacy Policy
  • Legal and Copyright Notices
  • Sitemap
  • Cookies

An Avnet Company © 2025 Premier Farnell Limited. All Rights Reserved.

Premier Farnell Ltd, registered in England and Wales (no 00876412), registered office: Farnell House, Forge Lane, Leeds LS12 2NE.

ICP 备案号 10220084.

Follow element14

  • X
  • Facebook
  • linkedin
  • YouTube