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G4 MDD main PSU connector pinout

EvieSigma

Young ThinkPad Apprentice
I have a G4 MDD (single 1.25GHz FW400) that doesn't power on, which I'm sure means a dead PSU. I managed to find a spare but I don't know if the spare works. What is the pinout of the main motherboard power connector so I can probe it and see if it's putting out anything?

 

MOS8_030

Well-known member
Here's how I mounted mine. I used a couple of sheet metal screws through the top. (under the plastic of course.)

I first tried some double-sided foam tape but it wouldn't hold long term.

These pictures were taken before I was completely finished.

I also had to get an ATX extension cable to be able route the wires behind the optical drives.

The power cord routes out through the  original plug hole in the back.

I also did have to invest in a Molex extraction tool. I tried other methods to remove the pins but finally gave in.

I think I paid about $16 for mine, I got it online somewhere.

MDD_g4x2_atx_1_sm.jpg

MDD_g4x2_atx_2_sm.jpg

 
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MOS8_030

Well-known member
Oh wow, it just fits. I thought it would be a lot tougher than that.
Yeah, it was actually pretty simple after I surrendered and bought the Molex tool.

I hate having to buy a tool for a single job but really it was necessary.

On one of the pages about the ATX conversion I saw a warning about some systems having problems with deep sleep.

I haven't seen that or any issues with my system.

I suppose heat could be a problem if I ran the machine really hard but I only use the system every few days mostly for iTunes or browsing the web.

 

Unknown_K

Well-known member
Any good websites on how to fix the old QS power supplies? I have at least 3 bad ones in the garage waiting for a cold day to get started on fixing them.

 

MOS8_030

Well-known member
Any good websites on how to fix the old QS power supplies? I have at least 3 bad ones in the garage waiting for a cold day to get started on fixing them.
None that I have found, and I looked pretty hard a few years back, otherwise I would have repaired mine then.

Reading around no one seems to have pin pointed a common failure mode, of if they have they haven't shared that info, unless something new has been posted in the last couple of years.

You can do the ATX mod to the QS too. But it's a bit more complicated.

http://atxg4.com/quicksilver.html

 
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Unknown_K

Well-known member
Mine died just sitting around and it might just be bad caps. One blows a fuse so I assume it has a shorted output somewhere and is probably not worth messing with.

 
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