silverknight
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New Raspberry Pi model A+ hdmi not working

Mon Nov 17, 2014 11:50 am

Hi all,

I have just got the new Raspberry Pi model a+ and was very excited. Removed the old model a, and replaced it with the new model a+'s 26 compatible pins. I started fine, and I can see it runs the code as it should. However, I have already run into two problems.

1.The HDMI port does not show anything on the screen anymore. This has never been an issue before. I use the LINDY hdmi to vga adaptor.

2.I was very excited to see how much the powerconsumption would decrease. But was very disapointed to see the powerconsumption actually increased by 50%, whitch was a bit of a blow.

I have just replaced the old model a with the new model a+ and copied a raspian image to a 16gb micro sd. I know there is not a lot of experence yet on the subject, but maybe some of you also will have simular problemems?

Best Regards Allan

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Re: New Raspberry Pi model A+ hdmi not working

Mon Nov 17, 2014 1:08 pm

1.The HDMI port does not show anything on the screen anymore. This has never been an issue before. I use the LINDY hdmi to vga adaptor.
Does the HDMI out work when connected directly to a HDMI input. That is the first troubleshooting I would attempt. If the HDMI video works connected directly, then there could possibly be an issue with your adapter or your adapter is looking for power from the HDMI port that is not there anymore.
2.I was very excited to see how much the powerconsumption would decrease. But was very disapointed to see the powerconsumption actually increased by 50%, whitch was a bit of a blow.
The A+ uses less power than the B+, it was never stated that it would use less power than the A/B boards.

Pi_Fanatic

silverknight
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Re: New Raspberry Pi model A+ hdmi not working

Mon Nov 17, 2014 1:22 pm

Hi Pi_Fanatic,

Thanks for the fast reply.

I will try with an other cable tomorrow. You are saying, that the HDMI out does not provide poweroutput as on the model a? That will make since, thanks.

They are stating all over the place, that the Raspberry Pi model a+ is using less power than all the other models.

http://en.wikipedia.org/wiki/Raspberry_Pi

http://www.raspberrypi.org/products/model-a-plus/

http://www.raspberrypi.org/raspberry-pi ... s-on-sale/ (video one at around 2:30)

I can live with the increased power consumption, but was not what I expected.

Best Regards Allan

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Re: New Raspberry Pi model A+ hdmi not working

Mon Nov 17, 2014 2:34 pm

1) How are you measuring power consumption?
2) The A+ now uses the same current limiting circuit for the HDMI H5V as found on the B+. It is possible that your HDMI adapter is drawing excessive current and being limited.
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Re: New Raspberry Pi model A+ hdmi not working

Mon Nov 17, 2014 7:35 pm

If the A+ is using (much) more power than the A, then something is wrong, it should consume at least 20% less, Does it still use more power when the HDMI cable is not connected? Look into the HDMI connector if you can see a bent pin or something like that.

silverknight
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Re: New Raspberry Pi model A+ hdmi not working

Mon Nov 17, 2014 7:40 pm

Hi jdb,

Thanks for asking. I simple look at the current draw from my powersupply. The current is measured with no hdmi attached. With the original Raspberry Pi model A, the current draw looked like this:

Raspberry Pi model A: 70mA
Others circuits: 30mA

With the new Raspberry Pi model A+, the current draw looks like this:

Raspberry Pi model A+: 120mA
Other circuits: 30mA

This results in an increase of 50% in total

My power supply delever approx 13Volts (simulating car battery voltage drop), whitch are switched down to 5Volts.

Well, I have noticed that, with the HDMI cable plugged in, the current draw in total is:
Usings Raspberry Pi model A: approx. 280mA
Usings Raspberry Pi model A+: appox. 250mA

It seems, that you gain some efficiency with the hdmi plugged in, but looses it with no hdmi. The power consumption difference is less on the A+. However, I have hoped the power consumtion, at least would have been the same, with no hdmi plugged in, as this would be the case in must of all aplications.

Best Regards Allan

silverknight
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Re: New Raspberry Pi model A+ hdmi not working

Mon Nov 17, 2014 7:42 pm

mahjongg wrote:If the A+ is using (much) more power than the A, then something is wrong, it should consume at least 20% less, Does it still use more power when the HDMI cable is not connected? Look into the HDMI connector if you can see a bent pin or something like that.
I have tried both hdmi plugged and unplugged, and even tried more than one model A+, since I bougth 5. Also tried to power the model A+, both from the usb power and the gpio, with no difference.

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Re: New Raspberry Pi model A+ hdmi not working

Mon Nov 17, 2014 8:14 pm

Hi again, I will do some precise current measurements tomorrow and post them here. I dont exactly remember them here now.

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Re: New Raspberry Pi model A+ hdmi not working

Mon Nov 17, 2014 9:14 pm

I would expect a model A to pull at least 300mA, and the A+ about 200.

70mA seems impossibly low.
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Jessie
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Re: New Raspberry Pi model A+ hdmi not working

Mon Nov 17, 2014 9:40 pm

Some power supplies loose efficiency when there isn't a big enough load on them.

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Re: New Raspberry Pi model A+ hdmi not working

Mon Nov 17, 2014 9:50 pm

jamesh wrote:I would expect a model A to pull at least 300mA, and the A+ about 200.

70mA seems impossibly low.
he seems to be talking about measuring the AC current on the primary side (mains side) of his supply, not on the 5V side.

His measurements are therefore invalid, as he doesn't know what the power supply "does".

Its probably a bit inconvenient that you need to split up a microUSB cable to measure the 5V current.

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Re: New Raspberry Pi model A+ hdmi not working

Tue Nov 18, 2014 11:21 am

HDMI on my A+ works fine, FWIW. I'm using a Philips HDMI monitor.

If one can power it through the 5V pin on the 40-way connector (I can't remember if that works), that would be more convenient for current measurements than the USB connector.
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silverknight
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Re: New Raspberry Pi model A+ hdmi not working

Tue Nov 18, 2014 12:03 pm

Hi,

I found out what was wrong regarding to the not working HDMI. It simply needed an "sudo apt-get update" and "sudo apt-get upgrade". The process took a while, since haven't upgraded for about 9 month (there was no need to and no internet, until now).

Regarding to the power consumption, it now behaves as expected. Can't say what was wrong.
My hardware now consume 80mA-90mA in total at 13VDC powersupply.

Im really gratefull for all the replies.

Best Regards Allan

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Re: New Raspberry Pi model A+ hdmi not working

Tue Nov 18, 2014 12:14 pm

yes the Upgrade will have been needed to make it boot properly

I believe your power measurements are invalid
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silverknight
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Re: New Raspberry Pi model A+ hdmi not working

Tue Nov 18, 2014 12:25 pm

RaTTuS wrote:yes the Upgrade will have been needed to make it boot properly

I believe your power measurements are invalid
My power Measurements may be invalid, just reading what the powersupply states. However, I do switch down the 13VDC input Down to 5VDC before feeding the Raspberry, which will transform the current as well. Im only interested in how long my car battery will last according to the 13VDC it supplies.

Best Regards Allan

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