Imac G4 backlight flashing for a second then turns off

[aaantonis]

Dear all,

I m taking this question out of my build thread, so as to reach a larger audience, as it tortures me for a week now. Future builders may probably find a solution to this specific problem more easily instead of searching through threads.
During my first build I faced the exact same problem and unfortunately I didn't document what I did to overcome it. In my build thread I told the story of how the G4 was stolen during an office robbery. Point is I don't have my previous Imac to see what I did.

The way I have the inverter hooked up is from the main filter with the ground attached to the faraday cage, I give power to the NUC's psu and from there to the PicoPSU. I connect the cables as per dremeljunkie's guide and the screen's backlight flashes for a split second and then turns off.

Has anyone faced this? or was I the lucky one to come across this, twice?

Thanks everyone.

 

[pgh]

Hello Aaantonis,

Try to hook it up to a ground (negative) of the psu /computer and not to the cage,
I remember having the Same problem in the past directly of the psu .... Not sure anymore but i thought the problem was the ground (negative) wire being to thin.... Hook up a thicker wire and test it again... Also try to atach the screen to the imac firmly maybe it helps as well... Whatever you do .... Dont short the wires and blow up the inverter... as the imac g4 inverter boards are almost imposible to find seperatly ! Good luck!

 

[aaantonis]

Thank you very much Pgh for your reply. I will try your thicker wire recommendations and see what gives. The ground was indeed connected to the psu. What I meant was that mactester57 mentions in a post that the faraday cage should be grounded to the wall outlet, (obviously through the AC filter at the input with the original cable)

 

[pgh]

With my monitor only mod indeed it is grounded trough the cage via the original imac /mickeymouse cable , but with my macmini mod inside it is not... And still everthing works fine...

It seems that your flashing screen has to do with the flow of the elec current to the inverter from your psu

So measure the Volts it should have and check the cables again or replace them with thicker ones starting with the ground... Still no result then put thicker cables on the 5v and 12v as well.... It must be a stable conection!

Here is an old post with my measurements of a 17 inch imac g4 inverter power consumption directly of an atx psu

https://www.tonymacx86.com/threads/...for-mactester57-ersterhernd-or-rick26.214280/