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Joined: Sun Dec 04, 2016 6:08 pm

HDMI To VGA and Avocent DSR8035

Sun Dec 04, 2016 7:21 pm


I'm a new convert to the world of Raspberry Pi and a huge fan. I have a couple Pi 3Bs and a couple of Pi Zeros I'm playing with.

I'm a Unix Sys Admin by trade so I'm pretty comfortable with Rasbian as it's very similar to Ubuntu machines I use at work.

Like at work, I want console to my Pi's, I don't want to have to plug in a keyboard and monitor everytime I need console to a Pi. I have an Avocent DSR8035 IPKVM. The DSR8035 is older hardware that doesn't support HDMI dongles, so I'm trying to use an HDMI to VGA converter. I've tested the HMDI to VGA converter by plugging it into my new Acer flat screen monitor and it works just fine. I've plugged the VGA dongle into a vintage VGA device and that works fine. However, when I plug the HMDI to VGA converter into the VGA dongle I'm having problems. The video display blinks on and then off and the screen flashes "No Signal", then it blinks on, I can see the console, then off again with "No Signal". It'll just keep doing this.

I read the FAQ on the Pi site about HDMI to VGA and have tried setting config.txt to the various recommended settings but to no avail. Here are the specs of what I'm using:


Raspberry Pi 3B

Raspbian GNU/Linux 8 (jessie)

UGreen HDMI to VGA Converter part number: 40248 https://www.amazon.com/gp/product/B00NB ... UTF8&psc=1

Avocent DSR8035 IPKVM

Avocent DSAVIQ-USB2 Dongle

# tvservice -n
# tvservice -m DMT
Group DMT has 15 modes:
mode 4: 640x480 @ 60Hz 4:3, clock:25MHz progressive
mode 5: 640x480 @ 72Hz 4:3, clock:31MHz progressive
mode 6: 640x480 @ 75Hz 4:3, clock:31MHz progressive
mode 8: 800x600 @ 56Hz 4:3, clock:36MHz progressive
mode 9: 800x600 @ 60Hz 4:3, clock:40MHz progressive
mode 10: 800x600 @ 72Hz 4:3, clock:50MHz progressive
mode 11: 800x600 @ 75Hz 4:3, clock:49MHz progressive
(prefer) mode 16: 1024x768 @ 60Hz 4:3, clock:65MHz progressive
mode 17: 1024x768 @ 70Hz 4:3, clock:75MHz progressive
mode 18: 1024x768 @ 75Hz 4:3, clock:78MHz progressive
mode 21: 1152x864 @ 75Hz 4:3, clock:108MHz progressive
mode 28: 1280x800 @ 60Hz 16:10, clock:83MHz progressive
mode 32: 1280x960 @ 60Hz 4:3, clock:108MHz progressive
mode 35: 1280x1024 @ 60Hz 5:4, clock:108MHz progressive
mode 36: 1280x1024 @ 75Hz 5:4, clock:135MHz progressive
# tvservice -s
state 0x120006 [DVI DMT (16) RGB full 4:3], 1024x768 @ 60.00Hz, progressive

I'm hoping someone can give me a clue what I need to do to make this work. I've tried many settings in config.txt, the ones I have active now are the closest to working. I've gone through all possible choices for config_hdmi_boost.

I'm willing to consider the UGreen is not the best chioce for a Pi, I bought it because it's powered and others have said they've had success with it with Pi.


Posts: 18
Joined: Sun Dec 04, 2016 6:08 pm

Re: HDMI To VGA and Avocent DSR8035

Tue Dec 13, 2016 5:37 pm

Well, I'm guessing there is no solution for me. I've tried everything I can think of. I've made nearly every configuration change that can be made, and I've tried several HDMI to VGA converters with no change. My best guess is that the power output simply is too low from any Pi converter. I've found other docs on Avocents where these devices have problems with laptops as well, so my best guess is that it has to do with power levels.


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Re: HDMI To VGA and Avocent DSR8035

Tue Dec 13, 2016 6:13 pm

Look for a high quality powered hdmi->vga converter, it may work. The un-powered converters are far less likely to work.
http://Mikronauts.com - home of EZasPi, RoboPi, Pi Rtc Dio and Pi Jumper @Mikronauts on Twitter
Advanced Robotics, I/O expansion and prototyping boards for the Raspberry Pi

Posts: 18
Joined: Sun Dec 04, 2016 6:08 pm

Re: HDMI To VGA and Avocent DSR8035

Mon Jan 02, 2017 5:09 pm

mikronauts wrote:Look for a high quality powered hdmi->vga converter, it may work. The un-powered converters are far less likely to work.
The first one I used was powered, hard to know about quality, I think it cost $14 as opposed to the $6 yo $8 I paid for the others which were all supposed to be pi compatible and are when I connect to my VGA monitor.


Posts: 18
Joined: Sun Dec 04, 2016 6:08 pm

Re: HDMI To VGA and Avocent DSR8035

Mon Jan 16, 2017 8:47 pm

WooHoo Success!!!

It's taken quite a bit of trial and error on this, but I finally have a solution.

My Avocent DS8035 is pretty old and covers 2 generations of hardware. I had been trying the newer dongles, the DRSAVIQ-USB2 which as the name suggests supports USB 1 and USB 2. I could not get these to work, no way no how. It was very frustrating, the activity light on the dongle would blink on for 2 seconds and off for 2 seconds during which time the video display would also blink on and off making it rather worthless. It did work enough so that I could see what state the Pi was in, but not enough to actually work with it.

When I bought the DSR8035 I thought there were only two versions of the dongle, the DSAVIQ-USB and the DSAVIQ-USB2. When I couldn't get the DSAVIQ-USB2 to work, I attempted to locate some of the DSAVIQ-USB in the hopes that being the older technology it might work better, but the only ones I could find were very expensive, more than I paid for the DSR8035 itself. Finally while googling to see if anybody else had experienced this issue, I found a post where an admin was having the exact same problem I was having but when connected to laptops. His solution was to use DSRIQ-USB. I was able to locate a couple of these on eBay for small dollars and bought them and......Drum Roll Please...... IT WORKS!!!

Basically from what I can tell the issue is the low power devices used by laptops and the Raspberry Pi. Where the DSRAVIQ-USB2 is a more current and more sophisticated device it also apparently requires more power which the Raspberry Pi simply cannot provide, not only does the Pi power the dongle through USB it also requires a good strong VGA signal to work.

For me, I don't require the additional benefits provided by the DSAVIQ, all I want and need is KVM to my Pi without having to plug in a keyboard and monitor every time I want to bring one of these online. Further I found 3 out of the 4 HDMI to VGA adapters I own work with the DSRIQ-USB. I have a CheTech, a VicTsing, an AbleConn, and a UGreen adapter, the only one that didn't work was the AbleConn, which is a shame as it's a much more substantial looking device than many of the others.

I was only able to test this with a Raspberry Pi 3+ and a Raspberry Pi Zero 1.3 as those are what I have on hand. One of the best things was that I didn't need to mess with the config.txt file to make this work, the 3+ and Zero 1.3 gave me video immediately upon power up. Your mileage may very with older Pis.

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Joined: Thu Nov 22, 2012 9:38 pm

Re: HDMI To VGA and Avocent DSR8035

Wed Apr 04, 2018 1:57 am

I got a few of the DSRAVIQ-USB2 dongles to work with Pi 2 and Pi 3 models, using a BENFEI HDMI to VGA active converted/adapter (similar to the UGREEN). I had to provide the HDMI to VGA device with 5v external source. This got my Avocent 2035 (ancient but works!) KVMoIP unit to see the dongles, and eliminate the screen blinking, and dongle flashing issue. I did have to tweak the HDMI over scan a bit, but that was more to address the VGA out to a HDMI monitor from the KVMoIP unit than a dongle issue per se. Oh, one of the dongles... does not pass a red signal, it did, but at some point in its use the red signal died. All other dongles tested provide RGB signals correctly.

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