Octane Lightbar Ideas

For discussion of triage and repairs to SGIs as well as general hardware questions
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GRudolf94
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Octane Lightbar Ideas

Post by GRudolf94 » Tue Jul 24, 2018 7:07 pm

So, my Octane arrived with both lamps on the lightbar dead. Woo. What a surprise. I didn't know the current LEDs would draw from there, but it'd surely be less than the incandescent lamps, which are as much of a resistor as a LED is a diode, so I put a blue LED straight into one position, and a green LED with a 0603 resistor crammed into one of the holes, with the LED cathode trimmed and soldered to the other side of said resistor, as a test.

In any case, this is a flaky setup, and neither of the LEDs are much happy. I don't think my hack was elegant (and I remember just guesstimating the resistor...at 47ohm, if memory serves. Anyone got a better idea on how to properly rebuild this thing?
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halfmanhalftaco
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Re: Octane Lightbar Ideas

Post by halfmanhalftaco » Wed Jul 25, 2018 2:15 am

To keep the look as close to stock as I could I replaced the bulbs with "warm white" LEDs in line with a resistor, but I can't recall the value off the top of my head. It's pretty trivial to calculate the needed resistor value if you know the LED voltage drop and current rating.
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johnnym
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Re: Octane Lightbar Ideas

Post by johnnym » Wed Jul 25, 2018 4:24 am

The Internet Archive has the page about Octane lightbar modding of Kurt Huhn archived. There you can find an example on how to calculate the series resistor.
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GRudolf94
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Re: Octane Lightbar Ideas

Post by GRudolf94 » Thu Jul 26, 2018 8:36 pm

johnnym wrote:
Wed Jul 25, 2018 4:24 am
The Internet Archive has the page about Octane lightbar modding of Kurt Huhn archived. There you can find an example on how to calculate the series resistor.
Thank you, that's very helpful. Didn't occur to me to measure the voltage on the lightbar board!
:Indigo2: R10k@195MHz/64MB RAM/XZ/ATX PSU conversion in the works/acting up
:Indy: R4600@133MHz/128MB RAM/XL-24/Gruesomely plasti-welded together
:Octane: R10k@225MHz/1536MB RAM/SSI

SGI Ultra64...erm, Nintendo64 console :D

and lotsa non-SGI stuff

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