Promethean Cable Length Issues

[Gongalong]

Hi folks,

 

We've been having frustrating issues with the latest 75" Nickel Promethean touchscreens and some new laptops we have, specificially Lenovo V15 and Dell Latitude 5511.

 

The problem seems to be that the laptop video signal isn't getting through to the touchscreen. Inevitably when these have been installed it's been done with 3-5m cables to a wallbox, then a 3-5m cable to the teacher's desk.

 

Promethean have said that they only guarantee connection with the 3m cable bundled with the screen, but inevitably 3m isn't always long enough to get a cable to a teacher's desk.

 

We initially thought it was just Lenovo V15s that had the issue, but the Latitudes are our most recent buy and they seem to have the problem as well.

 

When raised with Promethean a couple of months ago they said they can reproduce and would produce a firmware fix, but we've received nothing so far.

 

Other than buying top quality cables (and perhaps seeing if we can get Promethean's own cables) what else can we do?

 

Thanks

[dobbyit]

I have a 75” board and had a display issue caused by a windows update with the firmware, I had to update board in the end (via the promethean management console) after a windows update.

I originally thought it was a damaged cable but didn’t make a difference, went direct from pc to board, no luck.

Think you can revert back to factory settings on board

[robyholmes]

Would a powered/active HDMI cable help?

[Gongalong]

I'll try anything at this point, I'd forgotten about active cables. Ironically they all seem to be too long for what we actually need, but Farnell seem to have several that don't require external power. The reason we like to have a wallbox is because that the cable to the teacher laptop inevitably ends up getting trashed, so it makes it easy to replace. Surely we're not the only school who does this?

[robyholmes]

I'll try anything at this point, I'd forgotten about active cables. Ironically they all seem to be too long for what we actually need, but Farnell seem to have several that don't require external power. The reason we like to have a wallbox is because that the cable to the teacher laptop inevitably ends up getting trashed, so it makes it easy to replace. Surely we're not the only school who does this?

Understandable, I like a wall plates too for that reason. Not an ideal solution but might be the only option short term.

 

I've come across USB issues before and installed a USB hub at the board end to solve that. Maybe a powered HDMI hub at the board end would help.

[Reverend_Dan]

We have been using these https://visionaudiovisual.com/product/tc3-pkpluspk10mcables/ with titanium boards and they have been fine on VGA and HDMI over this length. I think the usb has a booster in but thats all. Just waiting on a 15m one to be installed so ill get back to you when that gets installed next week. We do have displayport to HDMI cables plugged into wall panels from dell 5260's

[SamanthaD]

At 5m you're reaching the end of passive HDMI, if not past it already. Add in extra connections and you lose effect meters. Active is the way to go. Appreciate the desire to keep the wallbox but a 10m active cable (search for Van Damme HDMI on CPC) should work with anything. Make sure you install it the right way around.

[Gongalong]

I didn't realise HDMI was so sensitive. We've run HDMI to TVs up to 20m without issue, although these were professionally installed.

 

Promethean are telling us that we have to use cables branded as "premium", and I've bought some sample 5m cables that match this description. They say we can't go beyond 7.5m in length, but from 5m in length I can only buy 10m, 15m etc. I can't find 7.5m. It's the wallbox though that we really want to retain, to save having to replace the whole cable, remove trunking etc.

[Driftingforlife]

Your not alone. We have had real trouble using 5m HDMI cables in the trunking on the wall, we started using the shortest cables we can get away with. Have been temped to try fibre hdmi cables. I have one at home that works great for gaming on my TV from my PC at 4k60.

[Gongalong]

I've had some mixed success with "premium certified" cables. In one classroom we have what I'm estimating is a 3m cable (non-premium) run to a wall plate, then we needed a 5m cable to get to the teacher's desk. I tried "premium certified" 5m cables from RS (described as "RS Pro"), Pro Signal, Antiference, and Cables Direct. The RS Pro and Pro Signal cables didn't work with our Dell Latitude 5511's, but the other cables worked. I still could not get Lenovo V15 laptops to work with the setup, but the Dell laptops are the priority.

 

In another classroom I had a 5m cable run to the wall plate, which is presumably also not using a "premium certified" cable, then a 3m non "premium certified" cable. This wouldn't work with the Latitude. I switched the 3m cable to a 1.8m Pro Signal cable, and that worked. I'm guessing it will be a game of trying different cables for the moment to see what works, but going forward I will ask our installer to use "premium certified" throughout, and hopefully that will be enough for the Latitudes to work.

[SamanthaD]

HDMI specs do not have a maximum length, and "premium certified" only ensure the cable is suitable for 18GBps and EMI shielded for protection against outside interference (an issue we've had in the past with radio mics). It doesn't guarantee cable length, especially if you're using pig tails to go through a wall plate.

 

If you want a reliable wall plate based solution then I can recommend the Extron DTP system. HDMI wall plate input which converts to a Cat6a cable (not IP) which feeds a receiver box at the projector. If you absolutely have to have wall plates this is the only way I would recommend it, and it ain't cheap!

[DavR]

We've had similar problems with Promethean Nickel panels, and also iiYama ProLites, in the configuration 3m HDMI wall run + HDMI coupler wall plate + HDMI fly lead. I can't comment on premium vs non-premium cables, but through trial and error I found that ALL cables were OK for a direct PC->board connection, but not all cables were OK for joining together in series.

 

I resolved the couple of problems that we had here by replacing all cables in the run, bar the wall plate itself, with new. For what it's worth, I used Amazon Basics(!) cables and they resolved the issue, and have been reliable since.

 

Bit narked that a) HDMI turned out to be flaky in this way after promising to be a nice clean digital upgrade and b) that our installers ran cheap HDMI cables that evidently weren't fit for purpose, but live and learn I guess.

[Gongalong]

a) HDMI turned out to be flaky in this way after promising to be a nice clean digital upgrade

Exactly. After decades of putting up with projectors we were selling touchscreens to teachers as this cure-all solution. Then they plug a laptop in and it doesn't work because the cable's a metre too long or the wrong type. Really it should be more robust.