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Thunderbolt


MattF

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Hi All - Looking for some insight from those that understand these things.

 

I came across my first Thunderbolt port in the wild the other day, and utterly failed to make it work.

 

The situation was this: Guest speaker has new MacbookPro (MBP) with associated thunderbolt I/O port, and also an Apple Thunderbolt to DVI cable adapter. We usually run from our older MBP, output on DVI, to VGA through an adapter cable, then into a (cheap) scan converter and onwards to the rest of our AV rack (including screens/ mixer/ scaler etc) then to projector. The system functioned fine with our older MBP outputting direct to DVI, however the new one wasn't having any of it. I was informed that the new MBP had been tested with an external monitor (input on DVI) and worked fine with the Thunderbolt to DVI adapter, as in "it just worked".

 

The signal from the new MBP wasn't getting to the preview screen, so the signal chain that wasn't working was Thunderbolt to DVI adaptor, DVI to VGA adaptor, VGA to scan converter, scan converter wizardry, BNC to preview screen. Plugging our MBP in at the point of DVI to VGA adapter functioned perfectly.

 

As you may have guessed, I'm no video wizz. I suspect either it's not outputting in a format that is readily converted to VGA, or it doesn't like the scan converter. Are either of these thoughts even close to the money?

 

Thanks for your time

 

Matt

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I assume you are using a passive DVI -> VGA adapter?

 

DisplayPort and Thunderbolt don't provide the analog component of the signal that the passive adapters use. You need to use a direct adapter (Apple certainly sell them, I have one on the desk next to me, other manufacturers probably also exist!)

 

T

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Hi Matt

 

The Apple Mini Display Port to DVI adaptor you would have been using is only DVI-D (There aren't 4 holes (for the analogue vga pins) around the flat spade connector). To make this work you would need a Mini Display Port to VGA adaptor (another £25 of course) to go into your scan converter. I'm surprised you managed to fit your DVI-VGA adaptor into the port of the newer Macbook adaptor to be honest!

 

Hope that helps

Lobba

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OK great, thanks for the replies.

 

I've just googled and discovered that Mini Display Port and Thunderbolt are physically the same connection (I'm a noise boy - give me a break), so the simple solution seems to be exactly as suggested; mini display port to VGA adapter. Grand.

 

I didn't have any trouble fitting the components together - that would at least have given me a clue if I'd had to force them.

 

Cheers guys

 

(and hi Tom - I did think about calling/ texting you anyway, but I lost my numbers a while ago... send me yours again if you'd be so kind...)

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I didn't have any trouble fitting the components together - that would at least have given me a clue if I'd had to force them.

 

The problem is that 'DVI' connectors come in a couple of variants - DVI-D which is Digital only and DVI-I which is digital and analog on (mostly) different pins (You also get DVI-A which is analog only e.g. for connecting a VGA only monitor to a computer with DVI-I ports with a cable) The passive DVI-VGA convertor is using the analog pins of the DVI-I connector to extract the analog signal. It's just a physical adaptation of the connector with no format/signal conversion. The thunderbolt-DVI adapter is DVI-D so digital only and you'd need a digital-analog active converter to make it work.

 

You have the solution now anyway, so hopefully you are now sorted!

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