Apple Cinema Display 23" - Blank Screen, "short-long-short" LED code

It's nice that Apple add the protection via the sense line for users that have a 20" & 30" displays & somehow manage to get the two power bricks mixed up. I expect a 30" monitor would melt a 65W brick if the center pins were blocked :^)

I shall try and get one of these…

http://uk.rs-online.com/web/p/linear-regulator/5339426/

& see if that makes it work without the sense line hack. It'll be interesting to see if it resolves it like A1082's posts on ehmac.ca.

I expect a 30" monitor would melt a 65W brick if the center pins were blocked :^)

And dangerously so, too! Expect a nice stinking bonfire if you try:-) That is why I mentioned "if you know what you are doing".

As to the low drop regulator: go for it, except the form factor may not be right, so you may have to rig it outboard, have read as much here before. Which I am sure you are perfectly capable of.

Also bear in mind that most rejected PC mainboards carry at least one of those you may want to recycle!

Good luck!

Recycle the planet!

I couldn't find any matching regulators on the dead PCB's I had lying around.

I replaced the voltage regulator yesterday & it worked :^)

I moved it off the main board because it was too cramped to fit the larger LM1086CS regulator in the same space.

I guess that the output from the reg has something to do with the PSU detection line (the center pins). Perhaps the PSU only works when it is recieving the correct voltage on those pins, it is weird that the 23" display wouldn't work with the 150W supply because of this failed (overvoltage) regulator. A1082's seemed to to be under voltage from what I can tell.

It seems to be back to normal now running fine with the original 65W PSU.

Thanks for all the useful links & info. I'm packing it up to give back to my happy freind.

Drew

Congrats, Drew. Somehow I knew you would manage.

To draw some conclusions from this: I am beginning to think there are at least 2 different malfunctions at stake in this thread, unless they may be related as you rightly suggest:

1. Sense line circuit malfunction. Solution: Jacobeons magic or a more neat variant.

2. Failing low-drop 3.3V regulator. Solution: replace by a bigger one (amp- and possibly form factorwise of course :-))

The reason for the regulator going astray/ failing is also not clear yet.

Any suggestions out there?

@ Drew: A1082's seemed to to be under voltage from what I can tell.

What exactly do you mean by that?

@ Drew: A1082's seemed to to be under voltage from what I can tell.

What exactly do you mean by that?

Sorry, I think you are correct, A1082 doesn't seem to say if the 1117 regulator was under or over voltage. I thought I had read that it was reading 0 Volts. He just says it had failed.

I was assuming that monitors that worked with the 150W supply may have an under voltage 1117 & ones that have an over voltage 1117 wouldn't work with the 150W PSU (this one was 4.2V). It did work with the pin hack, so I suspect that the 3.3V is used as a part of the sensing.

There must be ciruits that drop the 24V input down to 5V for the voltage regulator so it's possible that they are at fault.

Well, Drew,

usual suspects in these kind of circuits are +12V, +5V and +3.3V, an occasional -12V unmentioned. Your LM1117 +3.3V are unquestionably dropping down from an already +5V powered circuit, see link: http://www.national.com/mpf/LM/LM1117.html# Overview , no doubt about it and hence 'low drop' or ' LDO'.

±4+V is unquestionably a (possibly dangerous) aberration which needs to be corrected ASAP. As you have just done. Good for you!

I am nor never have been aware of any existing "overvoltage regulators", though electronically, it can effectively be done.

Your suggestion that the aberration on the regulator's output may well be the cause of the sense line malfunction is well worth investigating. So I will. Given time...

Good luck!

My 23" Cinema Display quit today in exactly the same way abundantly described in this thread. I tried disabling the middle pin of the power connector on the white brick, as described somewhere in the first few pages of the thread.

It worked!

All I did was put a thin ribbon of black plastic electrical tape over the contact.

I wonder if, after a period of normal operation, whatever protection circuit in the brick might be reset, and I could take the tape off.

Like others reporting here, my problem started in association with some reconfiguring in my studio, even though I was moving a computer other than the system that developed the fault. Perhaps something to do with momentary voltage fluctuations associated with unplugging and replugging other equipment? I dunno.

Just happy to have my main monitor working again.

Per hexdiy's comments in the post preceding mine above: Is there anything dangerous in continuing to run with that middle pin masked out? Thanks..

louis1946 wrote:

Per hexdiy's comments in the post preceding mine above: Is there anything dangerous in continuing to run with that middle pin masked out? Thanks..

It depends on how well you have masked the pin.

A few people have mentioned the connector has scorched or burned a little after this hack - it seems likly that the masking has moved to cover other pins. This means that the full 24V, 1.5A input is now running across one side of the connector instead of two. There is probably a good reason Apple added 10 pins instead of only 5 (3 pins could work on a circular connector).

Personally I think if you can open the case it would be safer to disconnect the grey wire (on connector J1) that connects to the center pin. Once inside the case it would also be worth checking the voltage regulator that A1082 mentions in the ehMac.ca posts. I found that one was supplying 4.2V instead of 3.3V. After replacing it I no longer needed to mask the center pin. The monitor works fine. The new regulator was about £3 with postage (GB Sterling).

The center pin is used (based on all the sleuthing here & elsewhere) to allow the main board to disable the inverter board if it detects a power supply that is 'under rating' because that would be a fire hazard. So if you somehow managed to hook up your 23" display (with the pin block hack in place) to a 20" power supply the monitor might work, but the power supply would be overloaded & may overheat or shutdown due to the monitor drawing more current than it is able to supply.

The service source manual states that following for the power supplies.

65W 90W 150W

ACD (20-inch) yes yes yes

ACD HD (23-inch) no yes yes

ACD HD (30-inch) no no yes

The pin hack overrides the built in protection that stops your display trying to use an unsuitable power supply, you should probably judge yourself if it is safe or not.

Many thanks for all this info, Drew. After the holidays, on a grey, boring winter day, I'll try to get inside the monitor, which is of course long out of warranty, and follow your suggestions for a more legitimate fix. - LJ

I have written up my experience with fixing a 23" Apple Cinema Display with the short-long-short error.

http://pixelchimp.net/blog/pixel-chimp/apple-23-cinema-display-possible-fix-shor t-long-short-error

I'm unsure if it is the 'real fix' but it worked for me.

Message was edited: corrected link

I can confirm the 150 brick trick.

My 2008 23" came back on instantly.

I too have a 23" display with a faulty 90W brick. It failed about 18 months ago and just sat on my desk under a sleeve. Today I read about the Jacobean fix, found the YouTube vide which clarified that I was trying to isolate the WRONG centre pin (the earth pin, not the tiny one in the LEAD COMING FROM THE MONITOR. It's a very fiddly mod; I used a bit of plastic from a milk bottle scraped down to very thin and put it over the male end in the block, then pushed the connector over it. All I get now is very brief flashes of life as if it's trying to get through and failing. I'll give it a few more tries and then start looking for a 150W power block.

Given the number of fails detailed here, and the fact there must be thousands more out there, it's disgraceful of Apple not to resolve it by sending out new blocks free.

treehousedaddy wrote:

I too have a 23" display with a faulty 90W brick. It failed about 18 months ago and just sat on my desk under a sleeve. Today I read about the Jacobean fix, found the YouTube vide which clarified that I was trying to isolate the WRONG centre pin (the earth pin, not the tiny one in the LEAD COMING FROM THE MONITOR. It's a very fiddly mod; I used a bit of plastic from a milk bottle scraped down to very thin and put it over the male end in the block, then pushed the connector over it. All I get now is very brief flashes of life as if it's trying to get through and failing. I'll give it a few more tries and then start looking for a 150W power block.

Given the number of fails detailed here, and the fact there must be thousands more out there, it's disgraceful of Apple not to resolve it by sending out new blocks free.

Be resonable, the 23" display was sold between June 2004 & November 2008. That means these displays are all over 3 years old. How long would you suggest Apple 'send out power blocks for free' ?

If you had Apple Care or it failed within the warranty (18 months ago) Apple would have fixed it.

The second reason I think your request is unreasonable is that the power supply is not the faulty part - it is the display that has failed. The center pin hack proves the supply works - so called 'faulty supplies' can power failed displays.

The center pin is wired differently on the power supplies so depending on the type of failure a 150W supply may or may not work. The center pin is used to disable the inverter board inside the monitor if it detects an unsuitable power supply. It is a safety feature to prevent a 30" display drawing too much current from a 65W or 90W power supply.

I hope you manage to fix your display, but blaming Apple with made up 'facts' about the numbers of affected units is not the solution. Arming yourself with a bit of knowledge will help.

Read my blog post if you want to see what I did to fix a freinds ACD.

Others have linked to usefull resources too. It sounds like your 'center pin block' isn't correctly blocking the pin, I also showed info on how to do the pin block inside the monitor, but it wasn't the real solution IMO.

Ouch! Do you work for Apple, Drew?

The fact is that I browsed for a solution at the time my display failed and neither found one nor posted that I had a problem. It's safe to assume that for every person who actually posts, there are several who either don't or don't find this particular forum to post to. So you're right, my figure of thousands is a "made up fact" but such was ever thus when it comes to estimating numbers. If you have precise figures, pray share them and explain how you got them.

Now I'm curious to know how you're so confident it's the display and not the block? I happen to have two displays, and therefore two blocks. If I swap them, as I did again between writing the first and second paragraph here just to check, I find that WOW! the display you adamantly pronounce broken works just fine. And the display that worked brillianto just a moment ago is as dead as the other was. Ergo, it's the block.

So now let's deal with my request that Apple responds by recognizing their manufacturing fault and shipping out blocks. It's clear by the number of posters, let alone the unknown number who haven't posted or have posted on all the other forums out there, that this is not just an isolated case here and there. It's also clear that for some people the problem lies in the block and possibly for others it's elsewhere, though I haven't seen proof of that, yet. Clearly it's one of those faults that develop prematurely but not prematurely enough for many people to benefit from the Apple warranty.

If Apple simply acknowledged the problem and replaced blocks free for those who sent in their faulty one, they'd be solving a problem for relatively small outlay (to them) and winning friends. I don't know what a block costs to manufacture, but allowing for reseller margins, shipping, packaging etc it's got to be no more than a third or less of what it costs the rest of us to buy. I suspect, thinking about what's in them, that the true cost is measured in units, not tens.

On the other hand, Apple has a consistent history of ARROGANCE towards its consumer base. So I'm not holding my breath.