Many of these cables are made with fairly cheap connectors which can get loose overtime. I have found that during the course of plugging my mini displayport connection from my CInema Display to my laptop I have to find a "sweet spot" by pulling the connector out a little bit and produce some tension. You could try this or just consider ordering an adapter from a company that offers a lifetime warranty: <http://estore.circuitassembly.com/products/Mini-Displayport-to-HDMI-Adapter.ht ml>. They are fairly cheap after all.
It's not the cable (at least for me) as it works fine in other applications. In fact my entire mini displayport -> DVI cable -> HDMI adapter -> HDMI still works fine for my TV but not my external Samsung 23" LED LCD monitor. The screen will just flash blue/desktop on the MBP and nothing outputs to the monitor.
Everything has worked fine since July when I bought both my 13" MBP and the monitor together. I unplugged, took to my dad's and when I came back, not working. I do believe I updated to OS 10.6.5 in between unplugging and replugging so perhaps I'll try a rollback and see.
Has anyone updated to 10.6.6 to see if that helps?
Apple needs to fix problem.
I too am experiencing this issue, but on a 2010 Mac Mini. My set up, however, involves using an HDMI to DVI-I dual link adapter (HDMI out from Mac Mini, and a DVI adapter to the TV).
I testing this quickly about a year ago and it worked. Now I want to use my Mac Mini as a dedicated media box so I went to look into hooking it up to the TV permanently. Nothing! However, the very same cables and set up work perfectly through my Windows HP laptop - both on Vista and Windows 7.
Curious, I test same set up back on the Mac Mini but via boot camp and Vista. Did not work.
I suspect there is something in the Mac OS now that is causing this problem .
Hopefully that is not the case and I am going to try a new (better) HDMI - DVI-I adapter to see if that fixes the issue with the Mac.
I've Macbook pro erly 2011 and i've two adapter mdp to hdmi, one moshi and one sqp, all two not work,
I brought my mac in three centers approved in a apple store, but was not detected anyhardware problem, before I had already triedtwo other adapters, but no one has ever worked with the graphics card amd 6490m. someone managed to use the adapter on amacbook pro 8.2 with this configuration:
Nome modello: MacBook Pro
Identificatore modello: MacBookPro8,2
Nome processore: Intel Core i7
Velocità processore: 2 GHz
Numero di processori: 1
Numero totale di Core: 4
Cache L2 (per Core): 256 KB
Cache L3: 6 MB
Memoria: 4 GB
Versione Boot ROM: MBP81.0047.B27
Version SMC (sistema): 1.69f3
Modello Chipset: AMD Radeon HD 6490M
Larghezza Lane PCIe: x8
VRAM (totale): 256 MB
Fornitore: ATI (0x1002)
ID dispositivo: 0x6760
ID revisione: 0x0000
Revisione ROM: 113-C0170H-521
Versione gMux: 1.9.23
Versione driver EFI: 01.00.521
Modello Chipset: Intel HD Graphics 3000
VRAM (totale): 384 MB
Fornitore: Intel (0x8086)
ID dispositivo: 0x0116
ID revisione: 0x0009
Versione gMux: 1.9.23
Risoluzione: 1680 x 1050
Profondità pixel: Colore 32 bit (ARGB8888)
Monitor principale: Sì
Integrato: SìI tried all combinations, with a power cord plugged in, starting with onlyboard amd, intel sole use of the graphics card viagfxcardstatus, no result on the screen is still no signal, for additional information I connect a LEDcinema display and it works,vga adapter and it works, the last test Iperformed was with a Minidisplay port to dvi to hdmi no signal but same result. I also made pram reset smc removed and put back the ram the same result. I hope someone has solved this problem, if someone hasthe same problem I could write to apple for a check on these models ofMacBook with 6490m graphics card amd. thanks for the help theygive me. Again, no technician is able to understand why not working any type of adapter hdmi