Mini Display port works on battery, not mains.

Hey people, hope your all doing OK.

I have an issue with my Mini DP, and its driving me mad.

Whilst running on battery, the Mini DP to HDMI works fine, and I get a lovely picture on my TV.

If I plug the mac into mains because the battery is running low, the TV gets the old fashioned style static, then goes black.

If I plug in the mini DP whilst the mac is charging, the TV doesn't even recognise there has been a connection and the screen stays black

As you may guess, this is annoying during films.

I thought the first cable I purchased was faulty (Only had tried it on mains power) so the store give me another one, and I got to keep the old one!
I got home, and plugged in the new cable, and it worked, so I thought I had a dodgy cable, Untill I plugged into the mains.

I then retested the first, thought to be broken cable, on battery power, and success!
It wasn't the cable, it was my mac.

I own a Mid 2010 macbook pro running Yosemite (Fresh install) that I am happy with, its still fast enough for me.

The battery charge cycle is at 1170, could this be anything to do with it? I was thinking maybe the battery swells when power is applied, breaking the Mini DP connection?

Any help much appreciated.

What's the mini DP you talk about?

pm-r said:

What's the mini DP you talk about?

Click to expand...

It is a mini display port, a proprietary apple connection to output video and sound to other monitors. It has been replaced by the thunderbolt connection.

Maybe I've posted this in the wrong area? Is there a more tech savvy part of the forum, as the mini display port is a well known connection.

This does seem to be an unusual situation. Since the problem seems to be power related…try doing an SMC Reset:

https://support.apple.com/en-us/HT201295

- Nick

pigoo3 said:

This does seem to be an unusual situation. Since the problem seems to be power related…try doing an SMC Reset:

https://support.apple.com/en-us/HT201295

- Nick

Click to expand...

Thanks nick, I'l try that out now.

Tried a SMC reset, still no joy. Outputs video and sound fine on battery power, but as soon as charger connected it wouldn't work. The charger actually broke yesterday and I had to order a new one, don't know if that could of been an issue.