[Arm-netbook] EOMA Micro Engineering Board case built

[luke.leighton]

On Mon, Aug 12, 2013 at 12:38 PM, joem <joem at martindale-electric.co.uk> wrote:
> On Mon, 2013-08-12 at 10:05 +0100, luke.leighton wrote:
>> On Mon, Aug 12, 2013 at 9:34 AM, joem <joem at martindale-electric.co.uk> wrote:
>> > On Mon, 2013-08-12 at 00:43 +0100, luke.leighton wrote:
>> >> awesome joe - i've linked it here:
>> >> http://rhombus-tech.net/community_ideas/micro_engineering_board/
>> >>
>> >> btw remember you'll need to do some mods to the MEB to make it useable.
>> >
>> > No problem - do you have a pdf of circuit diagram?
>>
>>  http://hands.com/~lkcl/eoma/meb/MEB.pdf
>
> Grumble mumble....
>
> 1. The PTC R1 is rated 0.23R. If 1V flows with D1 taken
> out, the loss is 0.23V. And its designed to trip at 1.3A.
> Not a good idea with SATA and stuff connected.
> Short R1 I recommend.

 ... that might explain why it's not possible to power up from 5V input.

> 2. D2 is rated 5.1V and is too ambitious if D1 is shorted.
> Remove D2 recommend.
>
> (Items such as PTC, D1, D2 should placed before a regulator
>  and at least 2V above the regulator output voltage.)
>
> Looking at these:
> http://rhombus-tech.net/community_ideas/micro_engineering_board/
>
> 3. REMOVE R2 *BEFORE* EVER POWERING UP!!!!!!!!!!

 yep.  otherwise it shorts ethernet PWRFBOUT to GND.

> 5. Short D1 - good idea, and use regulated 5V power supply - current
> requirement is 2A ?

 2A is more than enough

> 6. I assume the pull up resistors for I2C is inside the EOMA?

 from memory: yes.