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PiRLP Suddenly Not Working


Russ Woodman
 

Hope someone can help me with this. Have an IRLP board pre-modded to run on 3.3v coming off a Raspberry Pi 2 (wired only). Finally got it hooked up and working earlier but after firing it up a second time, Pi will not boot with the PiRLP board connected. Disconnect ribbon cable, Pi boots fine. Re-connect, nothing. Disconnected 3.3v jumper on PiRLP board and Pi boots fine, presumably because it is not getting power. Ribbon cables are connected correctly and this was working (one time) before bringing it home to power on again. Any help would be appreciated.

73 de Russ, K5TUX
Linux in the Ham Shack
https://lhspodcast.info


David Cameron - IRLP
 

Something is dragging either the 5v or 3.3v rail on the pi towards ground. 

Are you sure you are orienting the red line on the gpio cable onto the pi correctly?

Also have you checked the gpio db25 connector for broken wires?

When the pi is running, check the voltage to the 3.3v jumper. 

Dave Cameron 


-------- Original message --------
From: Russ Woodman <k5tux@...>
Date: 2/12/20 4:15 AM (GMT-08:00)
To: IRLP@irlp.groups.io
Subject: [IRLP] PiRLP Suddenly Not Working

Hope someone can help me with this. Have an IRLP board pre-modded to run on 3.3v coming off a Raspberry Pi 2 (wired only). Finally got it hooked up and working earlier but after firing it up a second time, Pi will not boot with the PiRLP board connected. Disconnect ribbon cable, Pi boots fine. Re-connect, nothing. Disconnected 3.3v jumper on PiRLP board and Pi boots fine, presumably because it is not getting power. Ribbon cables are connected correctly and this was working (one time) before bringing it home to power on again. Any help would be appreciated.

73 de Russ, K5TUX
Linux in the Ham Shack
https://lhspodcast.info


Russ Woodman
 

Hi, Dave.

I am 100% sure the cable is connected correctly. It would appear that the problem is on the IRLP board, not the Pi. I say this because if I leave the ribbon cable connected and unsolder the 3.3v jumper mod on the IRLP board, the Pi will boot fine. If I solder it back up again, Pi doesn't boot. Is there someplace I can look on the IRLP board for a short or cold solder or something? This was work in its exact configuration 45 minutes before I powered it on the second time.

Russ


David Cameron - IRLP
 

Under normal circumstances, with all LEDS lit, the board draws less than 80mA at 3.3V. Without any LEDs it is in the order of 2mA.

Can you take a picture of the mod you did to bring 3.3V? Maybe I will see the issue. Both the top and bottom of the board.

There are lots of locations where a short could be in the board. A cold joint would never cause a short, it would cause it to be open.
I would look more carefully at the GPIO cable as it is more suspect.

Also, check the resistance to ground from the 3.3V jumper to the board ground.

The other thing to do is try to power on the system, and feel around the chips on the IRLP board for something getting hot. Nothing should be mildly warm.

Dave Cameron
VE7LTD

On 2020-02-12 09:55, Russ Woodman wrote:
Hi, Dave.
I am 100% sure the cable is connected correctly. It would appear that
the problem is on the IRLP board, not the Pi. I say this because if I
leave the ribbon cable connected and unsolder the 3.3v jumper mod on
the IRLP board, the Pi will boot fine. If I solder it back up again,
Pi doesn't boot. Is there someplace I can look on the IRLP board for a
short or cold solder or something? This was work in its exact
configuration 45 minutes before I powered it on the second time.
Russ
Links:
------
[1] https://irlp.groups.io/g/IRLP/message/76813
[2] https://groups.io/mt/71210430/500965
[3] https://irlp.groups.io/g/IRLP/post
[4] https://irlp.groups.io/g/IRLP/editsub/500965
[5] https://irlp.groups.io/g/IRLP/leave/defanged


Russ Woodman
 

Pictures included. Note that this board was ordered PRE-modded for 3.3v. I did not do the mod myself.


On Wed, Feb 12, 2020 at 10:59 AM, David Cameron - IRLP wrote:
Under normal circumstances, with all LEDS lit, the board draws less than
80mA at 3.3V. Without any LEDs it is in the order of 2mA.

Can you take a picture of the mod you did to bring 3.3V? Maybe I will
see the issue. Both the top and bottom of the board.

There are lots of locations where a short could be in the board. A cold
joint would never cause a short, it would cause it to be open.
I would look more carefully at the GPIO cable as it is more suspect.

Also, check the resistance to ground from the 3.3V jumper to the board
ground.

The other thing to do is try to power on the system, and feel around the
chips on the IRLP board for something getting hot. Nothing should be
mildly warm.

Dave Cameron
VE7LTD

On 2020-02-12 09:55, Russ Woodman wrote:
Hi, Dave.

I am 100% sure the cable is connected correctly. It would appear that
the problem is on the IRLP board, not the Pi. I say this because if I
leave the ribbon cable connected and unsolder the 3.3v jumper mod on
the IRLP board, the Pi will boot fine. If I solder it back up again,
Pi doesn't boot. Is there someplace I can look on the IRLP board for a
short or cold solder or something? This was work in its exact
configuration 45 minutes before I powered it on the second time.

Russ


Links:
------
[1] https://irlp.groups.io/g/IRLP/message/76813
[2] https://groups.io/mt/71210430/500965
[3] https://irlp.groups.io/g/IRLP/post
[4] https://irlp.groups.io/g/IRLP/editsub/500965
[5] https://irlp.groups.io/g/IRLP/leave/defanged

 


David Cameron - IRLP
 

Did you not see the solder splashed all over ic U4? There is your short! It looks cold - you should be able to just pick it off.

David Cameron 

-------- Original message --------
From: Russ Woodman <k5tux@...>
Date: 2/12/20 12:36 PM (GMT-08:00)
To: IRLP@irlp.groups.io
Subject: Re: [IRLP] PiRLP Suddenly Not Working

Pictures included. Note that this board was ordered PRE-modded for 3.3v. I did not do the mod myself.

On Wed, Feb 12, 2020 at 10:59 AM, David Cameron - IRLP wrote:
Under normal circumstances, with all LEDS lit, the board draws less than
80mA at 3.3V. Without any LEDs it is in the order of 2mA.

Can you take a picture of the mod you did to bring 3.3V? Maybe I will
see the issue. Both the top and bottom of the board.

There are lots of locations where a short could be in the board. A cold
joint would never cause a short, it would cause it to be open.
I would look more carefully at the GPIO cable as it is more suspect.

Also, check the resistance to ground from the 3.3V jumper to the board
ground.

The other thing to do is try to power on the system, and feel around the
chips on the IRLP board for something getting hot. Nothing should be
mildly warm.

Dave Cameron
VE7LTD

On 2020-02-12 09:55, Russ Woodman wrote:
Hi, Dave.

I am 100% sure the cable is connected correctly. It would appear that
the problem is on the IRLP board, not the Pi. I say this because if I
leave the ribbon cable connected and unsolder the 3.3v jumper mod on
the IRLP board, the Pi will boot fine. If I solder it back up again,
Pi doesn't boot. Is there someplace I can look on the IRLP board for a
short or cold solder or something? This was work in its exact
configuration 45 minutes before I powered it on the second time.

Russ


Links:
------
[1] https://irlp.groups.io/g/IRLP/message/76813
[2] https://groups.io/mt/71210430/500965
[3] https://irlp.groups.io/g/IRLP/post
[4] https://irlp.groups.io/g/IRLP/editsub/500965
[5] https://irlp.groups.io/g/IRLP/leave/defanged

 


Russ Woodman
 

Dave,

Completely did not see that.  No idea how I missed it.  I was able to remove the cold solder drop there on U4 and now everything is working again.  Many thanks.

73,
Russ