21" Cinema Display blown backlight tube?

[CelGen]

I picked up one of the original 21" ADC cinema displays for the G4 for a reasonable cost (nothing) and it appears that the bottom backlight tube is a little on the weak side (takes a minute or two to get fully bright) and the one on the top does not light up at all. The power light blinks a fault code which eludes me at the moment.

I'm ware that the inverters on the smaller 17" are very well known for a similar issue however I'm not sure just how similar my issue is to the 17" model, or if the DIY repair steps are similar.

Has anyone else had to go through this and can explain what's up before I split the monitor open and start poking around at the inverter board?

 

[beachycove]

I would suspect the inverter, as it is a known point of weakness in all these screens. I have a 17" ADC screen in which I initially thought the trouble was the backlight. Turned out to be the inverter.

Replacements for the failed rectangular components on these boards must be available somewhere, one would think. I fixed my 17" by sourcing an inverter board from a replacement screen with broken plastics, but I remember thinking at the time that it would be a reasonably simple soldering job to replace the faulty components. I just don't know what to look for or where. If I did, I'd want to source a few spares, just in case. The entire inverter board is hard to find and expensive to buy when found.

 

[CelGen]

Do we know what exactly goes ont he inverters? Transistors? The transformers?

Google says a lot of people just replace the board. Nobody actually looked into the source of the problem.

 

[beachycove]

The rectangular components that seem to fail are wound with copper wire, or are in the case of the 17" equivalent to your unit. I am klutz enough not to know what the components are called. On some units, there appears to be a sticker on top reading "High Voltage."

Some good pics of the 17" screen, which seems particularly susceptible to this problem, here, down the page a smidgeon.

Note the presence of electrolytic capacitors on the board. I have occasionally wondered ....

 

[CelGen]

Okay, so the transformers have blown.

If that's the case, I jsut need to salvage compatible units off another LCD screen inverter.

 

[beachycove]

There is a DIY repair guide "out there" somewhere that describes repairing the 17" screen's inverter board by salvaging components from another failed board (only one of the components had died in each case). I had this some months ago, and seem to recall that a means of testing in situ was described, so it might be useful to do a little googling for guidance. I was planning to source the bits and pieces in order to try a similar repair for my 17" screen, but a donor unit came my way instead.

There is obviously no guarantee that this is going to work, but it is worth a shot if it can be done on the cheap. A new inverter board purchased through the usual online retail channels would set you back about $100 when all is done, and that would be pointless.

Can't find that link mentioned in my first paragraph just now, but this one may help.

Do report back if successful. This is likely to become an ever-more-common complaint.

 

[techknight]

doubt it.

if the transformer went, the inverter wouldnt stay on. or come on at all.

The CCFL lamp inside the panel itself would be the more likely cause.

 

[CelGen]

Unless the transformer for the top tube is blown and the others are not yet.

I still need to crack this thing open and check it out but right now it's buried in a crawlspace and that's a damn lot of screws to take out to open it. xx(

As a plus though, I did find a set of two new inverters for the 17" displays.