Loading ...
Sorry, an error occurred while loading the content.

MITS 4K SRAM "bypass resistor" question

Expand Messages
  • corey986
    I noticed that 3 of my ram cards have 4ohm 5w bypass resistors over the voltage regulators and 1 doesn t. It doesn t appear that the bypass resistor ever was
    Message 1 of 2 , Jan 26, 2014
    • 0 Attachment
      I noticed that 3 of my ram cards have 4ohm 5w bypass resistors over the voltage regulators and 1 doesn't.  It doesn't appear that the bypass resistor ever was installed since I don't see any "solder" tinning on the tabs.  Now this card did start out as a 2k card, so it would have sourced less current.

      Should I install one or is my non-upgraded early altair supply dropping down enough in voltage with 8 full slots to keep the 7805 sourcing what is needed on the card without thermal shutdown.  I've never had a problem with the card, I'm just worried if it will be.

      Thanks,
      Corey 
    • mfeberhard
      The other factor that affects this question is how fully loaded is your Altair? With a very lightly-loaded Altair, the input voltages to these regulators is
      Message 2 of 2 , Jan 27, 2014
      • 0 Attachment
        The other factor that affects this question is how fully loaded is your Altair? With a very lightly-loaded Altair, the input voltages to these regulators is higher, and the regulators will get hotter.

        If it were mine, I would not add the resistor. The card will work fine without it - maybe the regulator will get a little warmer with extended use.

        The 7805 regulator has a thermal shutdown circuit, so even if it gets too hot, it will just go into shutdown, without damage. :-)
      Your message has been successfully submitted and would be delivered to recipients shortly.