Apple 27" Cinema Display (A1316) has trouble turning backlight on

[Misterkeeks]

Re: Apple 27" Cinema Display (A1316) has trouble turning backlight on

I agree with RJ. In order to test this, heat up the caps with a hair dryer, so the caps are warm, but not hot that you burn yourself. Then turn the monitor on and see what happens.

This does seem like a bad capacitor on the power supply, The weak capacitor will take some time to charge to the full voltage, so by turning down the brightness/backlight will allow the cap to charge with minimum current being drawn from the circuit. Once the cap is charged, you can then draw more current from that circuit.
If the brightness is tured up at start, the caps voltage will be too low tripping the led's error circuit and shutting it down.

So, I ended up trying a replacement power supply as I got one for a lower price than they usually go. Issue persists in the exact same way.

So, next suspect I guess is the main board, which also contains the backlight circuitry. I’ve attached a stock photo of this board to the post. The backlight connector is the black plastic connector on the bottom left/middle area.

Seems like there are a lot of SMD electrolytic capacitors, as well as some voltage regulators (?) in that region. I can replace the whole board for $35, but are there any things I can diagnose now with a multimeter?

Also, is it possible that failing LEDs would require more current to start up, thus causing an intermittent failure to turn on the backlight?

I guess I’ll try the hairdryer trick on the main board as well.

[CapLeaker]

Re: Apple 27" Cinema Display (A1316) has trouble turning backlight on

I agree with RJ. In order to test this, heat up the caps with a hair dryer, so the caps are warm, but not hot that you burn yourself. Then turn the monitor on and see what happens.

[R_J]

Re: Apple 27" Cinema Display (A1316) has trouble turning backlight on

This does seem like a bad capacitor on the power supply, The weak capacitor will take some time to charge to the full voltage, so by turning down the brightness/backlight will allow the cap to charge with minimum current being drawn from the circuit. Once the cap is charged, you can then draw more current from that circuit.
If the brightness is tured up at start, the caps voltage will be too low tripping the led's error circuit and shutting it down.

[Misterkeeks]

Re: Apple 27" Cinema Display (A1316) has trouble turning backlight on

If your back lights stay on, when the level is turned down to next to nothing, then one or more LED's in the back light strip could be still bad. LED's can fail like that.

I think maybe I provided an iffy problem description.

If I turn the display brightness all the way down before connecting the monitor (and thereby turning it on, as it has no physical button of any kind), the backlight successfully turns on, after which I can turn it up as much as I want with no issues.

Basically, once the backlight is on, things are fine. No problems.

But getting the backlight on requires the brightness to be turned way down, or it won't turn on.

[CapLeaker]

Re: Apple 27" Cinema Display (A1316) has trouble turning backlight on

If your back lights stay on, when the level is turned down to next to nothing, then one or more LED's in the back light strip could be still bad. LED's can fail like that.

[Misterkeeks]

I have an Apple A1316 27” Display (non-Thunderbolt) that is exhibiting a weird backlight issue.

When first plugged into a computer, when it receives a signal, the backlight flickers briefly but fails to stay on. Otherwise the monitor works fine (the computer thinks another monitor is attached, I can see that it is displaying using a flashlight).

I tried turning it's brightness all the way down before connecting it. When connected, it flickered, then stayed on. So it seems that it can barely muster enough energy to turn the backlight on, but once it's on, it's fine. Other people have had issues with no backlight after a period of functionality, my issue seems to be kind of the opposite.

What should I start testing on this? It seems like the power supply just can't handle the load it's getting all of the sudden.