Macintosh IIFX intermittent power issues

[Happy_Mac]

Not sure if my post went thru last time so I will try again. Acquired a IIFX. Replaced batteries. Replaced floppy drive for known working one. Upgraded memory to 64mb (ouch on cost but glad is available). Cleaned board and thoroughly dried on dehumidifier. Installed bluescsi with 5 180mb partitions-all recognized and working. Installed 7.5.5 from 1.4mb floppies. It worked right from the start, well had some bad RAM but after I removed that it chimed and booted.

So the issue is sometimes when I boot it the PSU spazes out and clicks several times then turns off. If I let it sit or try it multiple times it will boot and then all is well. Solid performance. Runs apps and games. No issues. So obviously a power on problem. I’ve ordered replacement caps (thanks to Branchus Creations for the part numbers) and will be recapping soon.

So do we think a recap will fix the issue? Is there a particular cap in the power up circuit that is of particular interest? Just curious if anyone has had this issue before.

Video attached and appreciate any input on the matter.

 

[Happy_Mac]

Not sure if my post went thru last time so I will try again. Acquired a IIFX. Replaced batteries. Replaced floppy drive for known working one. Upgraded memory to 64mb (ouch on cost but glad is available). Cleaned board and thoroughly dried on dehumidifier. Installed bluescsi with 5 180mb partitions-all recognized and working. Installed 7.5.5 from 1.4mb floppies. It worked right from the start, well had some bad RAM but after I removed that it chimed and booted.

So the issue is sometimes when I boot it the PSU spazes out and clicks several times then turns off. If I let it sit or try it multiple times it will boot and then all is well. Solid performance. Runs apps and games. No issues. So obviously a power on problem. I’ve ordered replacement caps (thanks to Branchus Creations for the part numbers) and will be recapping soon.

So do we think a recap will fix the issue? Is there a particular cap in the power up circuit that is of particular interest? Just curious if anyone has had this issue before.

Video attached and appreciate any input on the matter.

So I fixed it. When replacing the leaky cap by C24 I lifted the pad off the electrolytic positive pad which I didn’t realize cut the connection to the next component. I bodged a wire from the new tantalum cap to the next component off the trace and now all is well. The pic is before the ripped trace. My opinion is if you don’t have a good heat gun for that method than the best way to remove old leaky electrolytic caps is the TWIST method hands down. I never rip traces with that method but I would consider myself an advanced beginner in soldering so maybe if you’re Bruce from Branchus Creations or the like you could do much better.