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I found that one resistor was missing next to the HDMI inter

Posted: Tue May 16, 2017 12:38 am
by gh0st2010
my raspberry pi 2 MODEL B is not boot~!!!!!
I found that one resistor was missing next to the HDMI interface (R14).
If that's the reason, what's the model number? Thanks

Re: I found that one resistor was missing next to the HDMI i

Posted: Tue May 16, 2017 4:50 pm
by Burngate
R14 isn't marked on the cut-down schematics, so we don't know what it does or its value.
It's interesting that, on the pictures I've looked at, it's not fitted on the Pi 3B, though it's there on the Pi 2B and the Pi B+

Are you sure it isn't booting?
Have you tried plugging into an analogue monitor, since Q2 seems to be connected to the CEC pin of the HDMI socket.

Re: I found that one resistor was missing next to the HDMI i

Posted: Tue May 16, 2017 5:24 pm
by hippy
Burngate wrote:It's interesting that, on the pictures I've looked at, it's not fitted on the Pi 3B, though it's there on the Pi 2B
For this Pi2B V1.2, using BCM2837, R14 does not appear to be fitted -

http://raspi.tv/wp-content/uploads/2016 ... 2_1500.jpg

But it does appear to be fitted for this Pi2B V1.1 using BCM2836 -

https://tr1.cbsistatic.com/hub/i/2015/0 ... -pi2-1.jpg

Re: I found that one resistor was missing next to the HDMI i

Posted: Wed May 17, 2017 9:45 am
by Burngate
It seems unlikely (though not impossible) that changing the SoC meant that resistor wasn't required.
Perhaps Q2 has been changed for a different type?

Re: I found that one resistor was missing next to the HDMI i

Posted: Wed May 17, 2017 10:20 am
by gregeric
I'd hazard a guess that R14 is the same pullup resistor as R15 on the CMIO boards, on the HDMI_CEC line. There it is a 27K pullup to 3V3 on the CMIO Rev 1.2, but not fitted on the CMIO Rev 3.0.

Re: I found that one resistor was missing next to the HDMI i

Posted: Wed May 17, 2017 11:23 am
by Burngate
So it is possible that the newer SoC has a built-in pull-up, negating the need for R14/15
CEC2.png

Re: I found that one resistor was missing next to the HDMI i

Posted: Wed May 17, 2017 11:29 am
by gregeric
Nah, the CMIO3 works with the CM1. Maybe they use an internal pullup, or it just isn't needed, WJDK.