15" Studio Display short-short-short blink, inverter issue?

Discussion in 'PowerPC Macs' started by didius, Jul 21, 2016.

  1. didius, Jul 21, 2016
    Last edited: Jul 29, 2016

    didius macrumors newbie


    Jun 6, 2015
    I have a 15" studio display which was hooked up to my G4 cube, recently it began to blink. Short-short-short blink, and I cannot adjust the brightness any more.

    I tried hooking it up to my powermac G4 MDD, and the same problem remains. According to Apple this code would mean "The display is detecting wrong video format or an unsupported resolution", but this doesn't seem right, resolution is 1024x768, which is supported.

    Any pointers?

    2016-07-30 UPDATE
    See below
  2. eyoungren macrumors Core


    Aug 31, 2011
    ten-zero-eleven-zero-zero by zero-two
    I get a blinking issue with my 20" Cinema Display from time to time. It's telling me the bottom backlight is dim (which it is when flashing).

    I've generally found that this happens after a period of time when the display is off then I use it for a while.

    Generally, letting the display stay on for a bit (so it heats up) and then disconnecting then reconnecting the ADC cable to my converter forces the bottom backlight back on which stops the blinking light.

    Not sure if my error and situation is the same as yours but I mention it if you want to try it.
  3. didius thread starter macrumors newbie


    Jun 6, 2015
    It is the bottom bit of the screen which is dim, I guess the bottom backlight is starting to fail? Are there replacements available?
  4. didius thread starter macrumors newbie


    Jun 6, 2015
    I decided to open the screen and check it's internal organs today.

    Something strange is going on here. I removed the backlights and connected them to the inverter. The top bulb is working. When I switched the bulbs around, then the bottom bulb (now connected to the top connector) was working.
    The issue doesn't seem bulb related. Apparently the bottom connector of the inverter isn't working.
    Any ideas of the inverter would be the culprit? Could the problem reside at the logic board? Is this fixable?
  5. Xandros macrumors regular

    Sep 19, 2010
    I'd hazard a guess and say that it is the inverter board. From looking at the circuit diagrams for my 23" acrylic the mainboard doesn't appear to be able to selectively turn on or off one or more CFL's on the inverter. It's one off all off as far as I can see from how it's wired up, so if it's able to power up one bulb it's probably working OK and the inverter is the culprit. If you've determined that the backlight CFL's work, but only on one of the transformers, then either something's wrong with the other transformer or something else on its circuit has failed (like a capacitor which might have failed open).

    Only thing that puzzles me and makes me think twice about all that I just said is the fact you get a short-short-short error code. You should be getting a short-short-long error code (backlight or inverter board fault). No idea why it's chucking out an error about potential dodgy video formats or resolutions.

    Anyway if it is indeed the inverter (still seems like it even with that error code), it might be fixable but it just depends on how adept you are at testing and replacing components (there are plenty of guides out there on those subjects of course). Usually though, the easiest method is to simply replace the offending board with a known working one. Though, those boards don't always come cheap even second hand. The inverter is, I believe Apple part number 922-5632.

    The alternative is to buy another working monitor on the cheap and cannibalise the parts. That's what I did with my 23" plus you end up with spare parts that way, which is always handy.

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