BATC Forum

This relates to my small-package Ryde RX - its worked fine since built, then one day the HDMI stopped working. No amount of card re-building, re-flashing of the RPI internals etc worked and I eventually got a replacement.
The same thing has just happened again......one failure I could claim reliability issues, twice is a bit of a long shot, especially as my standard RPi for Ryde car building has suffered far more in/out plugging and improper shutdowns etc.
I've tried 'safe mode' - the screen recognises something is sending it something but remains black - no string of boot-up messages. If I connect to the second HDMI I see the RPI boot up messages but then stops short of running long-mynd.
The screen check routine delivers the following....

device_name=LLP-32V3H-H6A
state 0xa [HDMI CUSTOM RGB full 4:3], 640x480 @ 60.00Hz, progressive
pygame 1.9.4.post1
Hello from the pygame community. https://www.pygame.org/contribute.html
(640, 480)
(1, 1)
6.032262903839108
no surface
no layer
Press enter to continue

The Power supply is a SMPSU and it delivers 5.21 to the RPI hearer pins. AT £40+ a pop this could get expensive.....any ideas what's going on? I have cross-checked the card with my other Ryde, it all works as expected.....
Thanks

Gareth

Hi Gareth,

Unfortunately it sounds like your setup might be damaging the HDMI output.
I wonder if there is some sort of grounding problem that is causing it.
Do both the monitor and the Raspberry Pi power supply have earth leads?
Is the negative side of the Raspberry Pi 5v supply earthed?

It is possible that the SMPSU has an isolated output. If that is the case then the ‘earth’ of the Pi could be floating with regard to the earth of the monitor. This can lead to a discharge when connecting which could be zapping the Pi.

Colin

Maybe what happened to myself may be relevant.

I use the Ryde with a small 11.5" monitor. Rather than use the PSU supplied with the monitor I used the shack 12V PSU which also powered the Ryde. One day there was no display on the monitor. This happened after doing some plugging/unplugging of the cables to tidy them up. It turned out that the HDMI input on the monitor had failed - the VGA input was OK so the monitor is still useful. I put this down to a possible earth loop issue.

I bought a replacement monitor and now use it's wall wart PSU (switching PSU) which has no connection to the earth terminal. Had no more issues since.

Nick - G4NKV

Hi Colin, it certainly seems like something like that is causing the 'failure' - "it worked, then didn't" when plugged into a different monitor....

The Ryde is on a 13.8v shack supply (which feeds pretty much everything). The SMPSU is an buck down-converter 3 amp eBay special and the DC 0V isn't isolated. The monitors I'm using are a recently acquired 12VDC 7" HDMI screen with in-built speakers (off the same shack 13.8 supply) and a spare computer screen with HDMI in (no speakers).
My card building RPI is on a standard Samsung USB-C phone charger and has been fine. Its been swapped between monitors too, so far so good.....

Shame as I built the mini-Ryde specifically for 13.8V /P use, with audio amp in too if needed. I will see if the RPI will still drive a 7" touchscreen, otherwise its going to be 'not much (any??) use'.....

Nick, interesting, although your RPI is OK but monitor not. Good old 'phono socket video' was never this much trouble.....

Gareth

Did you say audio amp? Is it a switching amp? Don't assume you can run that off the same PSU and have a common ground.

Mike

Mike, yes, it's a small class D amp, but 'designed for 5V'. I'll check it but I used the same in my Portsdown/Langstone combo and haven't had any trouble. But no hdmi out on that one, just the internal 7" pi screen.....
Gareth.

Just checked, the audio ground is common to the RPI DC ground so I don't think its that.
If the RPI does still drive a 7" touch-screen, I will swap it out for another one and then add/use a new DC out from my Mini-Ryde (straight off the 12V in basically) for exclusive use with the little monitor, also 12V.
Gareth

Hi Gareth,

It sounds like its only the 1st HDMI that has gone pop and the 2nd is still ok as Ryde doesn't work on the second port normally anyway.

It is possible to get Ryde to run on the 2nd port but I've not had time to write the code to make it easy/automatic yet. The current HDMI port switching procedure involves manually modifying code and recompiling things but I have had it working as a proof of concept.

So there is hope for some further life for you Pi yet.

Tim

Thanks Tim, as and when.......and yes, the second port does work as mentioned earlier. Shame its not as easy as picking an audio device e.g. If the hardware is fitted, why bury access to it?? I really don't understand RP Foundation sometimes....
Gareth

Well the 'good news' is that the RPI4 with the dead HDMI port still works fine with a 7" RPi Touchscreen, so I'm able to 'swap RPI4's' from my development Portsdown/Langstone to the mini-Ryde.

Like all failures, it would be useful to know WHAT caused this (second) failure. I'll certainly be more careful about 'hot-swapping' HDMI (and USB leads, although both my Portsdowns have been fine), bit of a pain with just one Minitiouner between two Ryde receivers. (I know, build another... )

Maybe its JUST been the HDMI...

Gareth