alexdev
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Is it safe?

Sat Dec 30, 2017 10:51 am

Hi! Recently I bought a Raspberry Pi 3 model B and an acrylic case with fan for it.
The first problem I encountered was the fact that the connector exposed the contacts and it could probably touch the other GPIO pins and make a short-circuit. I've fixed this problem by bending the opposite pins a bit and by putting some tape on the connector side.

Now, I've read on this forum that the Pi "will fry" if I use a fan on the 5V rail. Is this true?
I've also read that the 5V rail is connected directly on the 5V output of the power supply.

Can anyone clarify this?

I get nice temperatures using the fan. I also want to overclock it and do some experiments, so a fan is must have for me. I want to use it as a 24/7 server too.

Another thing: during the boot process, the fan speed is low, and after some seconds it reaches full speed. What's happening?

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mahjongg
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Re: Is it safe?

Sat Dec 30, 2017 11:16 am

you are too afraid!
yes, the GPIO pins are exposed, that doesn't matter, in any computer there are pins and components that carry voltages, unless you deliberately create short circuits. so don't stick a knife in there.

you can connect a small fan to the 5V and GND GPIO pins, one that draws a few hundred mA, not much more.
If your ventilator starts running slower, its an indication that it is getting less energy (Voltage), so how is it connected?

also a fan is really only needed if you are using the PI heavily, like watching a movie, or running other GPU intensive software.

alexdev
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Re: Is it safe?

Sat Dec 30, 2017 11:22 am

So, everything should be fine?

I have the fan connected on 5V and GND pins.
No, the problem is not the fact that the GPIO pins are exposed. The problem is that the FAN connector have the 2 contacts (5V, GND) exposed to the side of the other GPIO pins and they touch each other if I don't put some tape.

Look:
Image

These pins touch the opposite GPIO pins.


I don't know how much current the FAN draws.

EDIT: This is the fan: https://www.lifestyleupdated.com/shop/f ... l-b-rpi-b/
Current: 0.2A

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mahjongg
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Re: Is it safe?

Sat Dec 30, 2017 11:32 am

there is one thing that can damage your PI, and that is if a true GPIO pin touches 5V, the PI's GPIO's do NOT tolerate being connected to 5V (or anything above 4V really). It can cause ""latchup" which can destroy the PI's main chip.

other than that really the worst that can happen is a blown polyfuse (which will self-heal if you un-power for a day or so), and any power fail (or drop) can cause damage to the SD-card (can corrupt it).

alexdev
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Re: Is it safe?

Sat Dec 30, 2017 11:36 am

Now after the "tape mod" the connector can't touch other pins.

Isn't 0,2A too much current ?

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mahjongg
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Re: Is it safe?

Sat Dec 30, 2017 11:39 am

200mA is fine, should not be a problem. I have no idea why the fan should slow down during bootup, except that a PI draws more current, because its power manager has not started yet.
More current could cause a drop in voltage the PI receives if you have a sub-optimal power cord, try a shorter thicker cord, preferably one that has visibly two wires, instead of one round thin one. watch the power LED, it should NOT go out (blink), and you should NOT get a lightning rod icon on your screen, those are indicators of power fails.

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HawaiianPi
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Re: Is it safe?

Sat Dec 30, 2017 11:52 am

The 5V GPIO pins are connected to the 5V rail, so a fan that doesn't need a ton of power will be fine. However, that 3 wire connector is odd. It looks like it has 2 grounds and a single 5V, while the Pi has two 5V pins and a single ground. You should replace that connector with one that fits better, and only uses one ground and 5V wire (don't connect the other wire).

On the other hand, fans are noisy and blow dust all over your Pi, so I don't like them. Get a Flirc case and you won't need a fan. The top and sides of the Flirc case is a one piece casting of aluminum that contacts the SoC (CPU+GPU), so the case itself acts as a huge heatsink. It will keep your Pi3 cool without the need for a noisy, dusty fan.

And it looks good too!
Image
Click picture for Amazon USA link.

There is a newer Gen2 version that is specifically made for the Pi3, and an older version for the B+/Pi2, but you can use the B+/Pi2 in the Gen2 case as well, you just won't be able to see the LEDs. I don't recommend a Pi3 in the older case because the SD card is hard to access.

If you hear the fan speed changing during boot, then your power supply is probably inadequate. Some phone charger type power supplies have very poor voltage regulation and will drop well below 5V under relatively light loads. They will still work fine for charging a phone, because battery charging does not require very precise voltage control (4.5V will charge your phone, but it won't run your Pi3).

It could also be the micro-USB cable you are using to connect the power to the Pi3. Many of those have thin wires with too much resistance to deliver the kind of current a Pi3 might need.

The official Raspberry Pi Foundation Pi3 power supply is rated for 5.1V at up to 2.5A and has nice fat 18 gauge power wires.
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alexdev
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Re: Is it safe?

Sat Dec 30, 2017 11:55 am

I have the RPi 3 original power supply that delivers 5.1V / 2,5A .

There is no lightning bolt on the screen and the red LED stays on. If I shut down the Pi the red light still remains on and the fan is still running at full speed until I disconnect the power cord.

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mahjongg
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Re: Is it safe?

Sat Dec 30, 2017 11:58 am

sounds perfectly normal, except that the fan should not slow down.
Are you using the original power cord that came with the supply?

alexdev
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Re: Is it safe?

Sat Dec 30, 2017 12:07 pm

The power supply cord cannot be detached.

I powered off the Pi and disconnected the power cord for a few seconds, and after I plugged it back in the FAN started at full speed.
Maybe the PSU needs a time to "warm" ?

The fan starts slow during boot process only if i don't power the Pi (and use the power supply) for a long period of time.

I'll let it cool down for an hour and plug the power cord without the SD card plugged in.

alexdev
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Re: Is it safe?

Sat Dec 30, 2017 4:52 pm

I unplugged the power supply from the wall outlet and after 2 hours I plugged it back, I removed the SD card from the Pi and plugged the micro usb connector. The FAN started at low speed and after a few seconds it reached full speed.

If I unplug the micro usb connector and plug it back in the FAN starts normally.

So maybe the power supply needs a time to "warm up".

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Jednorozec
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Re: Is it safe?

Sat Dec 30, 2017 5:16 pm

It's more likely that the fan needs to warm up. The bearings may be a bit sticky after the fan sits for a while.
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alexdev
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Re: Is it safe?

Sun Dec 31, 2017 8:07 am

You're right. I used another power supply and the FAN did the same thing.

overlord santoski
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Re: Is it safe?

Sun Dec 31, 2017 11:33 am

To actually run out 24/7 server off of raspberry does not require you to overclock really the only thing that you need to overclock it for is possibly if you are running really powerful programs that otherwise would require more processing power than what the pi can provide I ran the server that ran 24/7 in all I really needed was a heat sinks and even that was Overkill as long as you keep it well-ventilated it should be fine but there really should be no reason to overclock a computer like that

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Re: Is it safe?

Sun Dec 31, 2017 11:50 am

Hello,
some 3 wires fans have a tachometric signal (speed rpm) on the third wire. Bur usually it's yellow.

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