T420 and Displayport audio problems

Discussion in 'Lenovo' started by Jesper Juul, May 12, 2011.

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  1. RabidBeaver

    RabidBeaver Notebook Enthusiast

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    Thanks for following up on this, Aakashn. Amazon has this nasty habit of switching suppliers on these kind of small devices and sometimes they aren't 100% compatible as you and I have found out with this adapter.
     
  2. Windsor

    Windsor Notebook Geek

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  3. oxlmoos

    oxlmoos Notebook Enthusiast

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    I'm following up on the issue I've previously posted on now that I have some new information. I bought the Startech DP2HDMI adapter that Jesper Juul has gotten to work. Adjusting my Samsung TV (LN32C350) to "screen fit" mode from 16x9 did fit the image properly onto the screen, but the fuzzy text remains (fuzziness which I don't have when connecting via VGA). I tried the adapter on a different Samsung panel (PX2370); I also needed to manually adjust this monitor to "screen fit" from 16x9, but I didn't have any fuzzy text. I had my text DPI modified in Windows so I set that back to normal to see if that had any effect, but it didn't make any difference. Apparently the Startech adapter works well in some situations, but not in all. I'm planning to try the adapter that others have recommended in the main T420 forum (see here).

     
  4. maksym

    maksym Newbie

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    Ok, so that what I have learned so far. My configuration:

    1) Lenovo ThinkPad T420 4177 Core i5 2410M (no nvidia, built-in Intel video only), Win 7 Pro
    2) Samsung 46" LCD, 2 HDMI port on the back, one on the side.
    3) Some Rosewill 6ft HDMI cable, look like this one Amazon.com: Rosewill RCE-6-MHE Pellucid HD Series 6 FT Mini-HDMI cable (High Speed with Ethernet) M-M: Electronics , but can't tell for sure.
    4) 25 ft cable, this one: Amazon.com: Link Depot HDMI to HDMI Cable (25 feet): Electronics
    5) StarTech DP-HDMI adapter, this one Amazon.com: StarTech.com DP2HDMI DisplayPort to HDMI Video Adapter Converter: Electronics .

    Before plugin any cables, I have the Conexant 20672 SmartAudio HD and Intel (R) display audio devices in device manager. I also have "Speakers at Conexant 20672 SmartAudio HD - Default device" in my Sound/Playback settings. No HDMI in Playback. "Show disabled devices" does not reveal HDMI either.

    1) Once I connect 25ft cable through the adapter to HDMI 2 TV port, I have no audio, and still no HDMI in Playback
    2) Once I connect 6ft through the adapter to HDMI 1 TV port, I have audio and HDMI appears in playback. Reconnecting 6 ft cable to HDMI 2 port also has audio.
    3) At this point, I reconnected 25ft cable to HDMI 1 through the adapter and got audio on it as well.
    4) Returned 25ft back to HDMI 2 and audio disappeared.
    5) Returned 25ft to HDMI to HDMI 1. No audio. Plugged the cable out of adapter, and plugged back - audio appeared. Tried 6ft - still audio in both ports.
    6) Switched 25ft to HDMI 2 - no audio. Switched back to HDMI - no audio. At this point, I am unable to get audio back on 25ft cable :)
     
  5. maksym

    maksym Newbie

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    Now, somebody has to figure out how to trick the auto-audio-detect in win 7 or in my TV.
     
  6. RabidBeaver

    RabidBeaver Notebook Enthusiast

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    Update on Displayport audio...

    I ordered the same Displayport to HDMI cable as Windsor:

    Amazon.com: 6FT Displayport-male To HDmi-male Adapter Cable: Electronics

    Mine was sent from J-Tech Digital.

    It works perfectly! When I plug the T420 into my Sammy TV, it automatically switches over to the other audio device for the DisplayPort and all audio comes from the TV. The mixer buttons on the laptop control this audio device. When you unplug the cable, everything returns back to normal. This is a true plug-n-play operation, you shouldn't have to muck around with any settings.

    Besides the working audio, I like the cable much better as there isn't a much junk hanging off the side of the T420.
     
  7. chx1975

    chx1975 Notebook Consultant

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    Displayport to HDMI, Displayport to HDMI Converter Cable, Manufacturer I bought this in 2009 for the T400s and it delivers audio for the T420. Although of course there is a lot of marketese and SEO text on the website wherever it counts they have the technical precision and I love them for it. It's extremely frustrating on some sites to figure out what a cable can do and what it can't.
     
  8. maksym

    maksym Newbie

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    It looks like any cable will do, as long as it supports 10Gbps speeds (HDMI Cat. 1.4), or go with Cat.2 to be on the safe side. I got two Cat. 2 cables (the ones with Ethernet), 6ft and 11ft, and they both work.
     
  9. blinder

    blinder Notebook Consultant

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  10. PatchySan

    PatchySan Om Noms Kit Kat

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    Can confirm the NEET adaptor works great, i'm using this with a cheap HDMI cable (v1.4) and it recognises my Sony TV straight away with sound.
     
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