jammincomedy
Posts: 8
Joined: Fri Aug 31, 2018 2:18 pm

Using VGA monitors with the Pi 3

Mon Oct 15, 2018 7:04 pm

Hello. I have four Raspberry Pi 3's that I am using. They are all connected to a VGA monitor with an HDMI to VGA adapter. The first day, all four of the PI's turned on the monitor displays. However, the second day, two of the displays would not turn on when plugged in to the Pi's. The monitors are fine as a Windows computer will turn them on. I also tried the Pi's that weren't turning on the two monitors on the other two monitors where the Pi's were working, and the two non-working Pi's would also turn on those monitors.

Is there anything I might check in the monitor settings that could affect its ability to pick up the Pi's? The Pi's have their resolution set to default monitor preference. Thanks.

klricks
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Re: Using VGA monitors with the Pi 3

Mon Oct 15, 2018 7:33 pm

jammincomedy wrote:
Mon Oct 15, 2018 7:04 pm
Hello. I have four Raspberry Pi 3's that I am using. They are all connected to a VGA monitor with an HDMI to VGA adapter. The first day, all four of the PI's turned on the monitor displays. However, the second day, two of the displays would not turn on when plugged in to the Pi's. The monitors are fine as a Windows computer will turn them on. I also tried the Pi's that weren't turning on the two monitors on the other two monitors where the Pi's were working, and the two non-working Pi's would also turn on those monitors.

Is there anything I might check in the monitor settings that could affect its ability to pick up the Pi's? The Pi's have their resolution set to default monitor preference. Thanks.
Make sure the monitors are turned on before booting the RPi.
Unless specified otherwise my response is based on the latest and fully updated Raspbian Buster w/ Desktop OS.

W. H. Heydt
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Location: Vallejo, CA (US)

Re: Using VGA monitors with the Pi 3

Mon Oct 15, 2018 8:11 pm

Also...enable to "force hdmi" flag in /boot/config.txt.

Further commentary... Examine the monitors to see if any of them have a DVI connector, if so, just get HDMI to DVI cables for those monitors.

andrum99
Posts: 927
Joined: Fri Jul 20, 2012 2:41 pm

Re: Using VGA monitors with the Pi 3

Mon Oct 15, 2018 10:31 pm

jammincomedy wrote:
Mon Oct 15, 2018 7:04 pm
Hello. I have four Raspberry Pi 3's that I am using. They are all connected to a VGA monitor with an HDMI to VGA adapter. The first day, all four of the PI's turned on the monitor displays. However, the second day, two of the displays would not turn on when plugged in to the Pi's. The monitors are fine as a Windows computer will turn them on. I also tried the Pi's that weren't turning on the two monitors on the other two monitors where the Pi's were working, and the two non-working Pi's would also turn on those monitors.

Is there anything I might check in the monitor settings that could affect its ability to pick up the Pi's? The Pi's have their resolution set to default monitor preference. Thanks.
The first thing to try is to make sure you have the monitor connected and powered on *before* you power up the Pi. This is because the Pi only looks for a monitor when it starts up. If it can't see a monitor at startup, the HDMI output get disabled. There is no auto-detection once the Pi has started up, so plugging one in after boot won't do anything - the HDMI output will stay disabled.

(Also, if the HDMI to VGA adaptor uses its own separate power supply, that obviously needs to be connected and powered on before your power up the Pi).

Also make sure that your Pi has an adequate power supply - the official power supply with the Raspberry Pi logo on it is recommended.

Failing that, you may just be unlucky and have 2 monitors that cannot be reliably detected at boot time by the Pi. There are various settings that can be used in /boot/config.txt to get around this (including hdmi_force_hotplug=1), and also to get around the fact that auto-detection only works at boot time, which is annoying. Try the simple fixes first though, as most monitors do work correctly.

jammincomedy
Posts: 8
Joined: Fri Aug 31, 2018 2:18 pm

Re: Using VGA monitors with the Pi 3

Wed Oct 17, 2018 1:18 am

Today, I tried one of the Pi's that was turning on a monitor on a second monitor that would not turn on with a separate Pi. It turned on that other monitor as well. However, when I took a Pi that was not turning on a monitor and put it on a monitor that was being turned on by the other Pi, it would not turn that monitor on. So, the issue appears to be with some of the Pi's.

Making matters worse, the Pi's will no longer turn on the 7-inch tablets that they came with. So, I'm not sure how to change their settings if I can't get them to display on the tablets or the monitors.

W. H. Heydt
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Joined: Fri Mar 09, 2012 7:36 pm
Location: Vallejo, CA (US)

Re: Using VGA monitors with the Pi 3

Wed Oct 17, 2018 2:48 am

jammincomedy wrote:
Wed Oct 17, 2018 1:18 am
So, I'm not sure how to change their settings if I can't get them to display on the tablets or the monitors.
Begin with the suggestions already offered. And, FYI, if you have enabled ssh, you can connect to a Pi remotely and edit the critical file, /boot/config.txt .

Edit to add... Bear in mind that all configuration information resides on the micro-SD card. So if the problem is in the configuration, it will "follow" the card. If the problem is the Pi hardware, it will "follow" the Pi. Test accordingly.

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hansotten
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Re: Using VGA monitors with the Pi 3

Wed Oct 17, 2018 10:22 am

In the past many posts were made concerning HDMI to VGA adapters suitable for a Raspberry Pi.

Not all were working, cheap ebay China ones even damaged the Pi due to excessive power taken from the Pi over the HDMI connection.
Some shops sell HDMI to VGA adapters known to work well.

Your report of Raspberry Pi's now not anymore working with the 7 inch display is alarming, you may have damaged the Pi's.

So this makes me wonder: what adapter are you using? One known to be working from reports or just a cheap unpowered one?
http://duinorasp.hansotten.com for Raspberry Pi and Arduino and ESP8266
http://retro.hansotten.nl for retrocomputing with the 6502 cpu

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