Mac IIci - Recapped and Won't Turn On

[AppleMacintosh]

I just recapped my Mac IIci. I was very careful. But I did wash by hand and dry the motherboard, just as I have done with other boards without problems. All the caps seem to have installed fine. But when plugged in, nothing happens. Pressing the power button does nothing. Pressing the power button on the keyboard does nothing.

Checked the power supply, and I appear to be getting the correct voltage (+5.12V) from the supply. Double checked proper seating of the power supply to the board, and it looks fine. But the board is dead.

Any ideas on what to check first?

 

[beachycove]

Check the rear power switch and/ or reset power management by pressing the cuda button?

 

[AppleMacintosh]

The switch appears to function based on a quick check with a multimeter. What is the cuda button?

 

[AppleMacintosh]

I researched the cuda button. The IIci doesnt have one. But I still suspect a similar issue.

 

[beachycove]

Thought it did. When was the CUDA button introduced?

Reseating the RAM is an obvious one, along with all cards/ connectors.

 

[zuiko21]

Not sure about the IIci, but some old Macs need a working Lithium battery in order to startup.

Maybe you could try to put near 5 V between pin 9 of the PSU connector and ground -- a similar procedure can be used for starting up a Mac IIx.

 

[IIfx]

You will need a working PRAM battery.

 

[AppleMacintosh]

I had installed a brand new 1/2AA 3.6V lithium battery when I did the caps. I went back and checked and the voltage from the batt is only 2.5V. The batteries are stamped with a May 2011 manufacture date so I thought they should be fresh. But I was expecting at least 3.6V. Could this be causing my problem? I am skeptical because it was booting fine off a much older battery a few weeks ago.

I rechecked a lot of my cap work and it looks fine. I can't figure out what I might have done to cause this, unless it was a stray static shock somehow.

 

[dougg3]

It probably won't be the battery causing the problems -- both of my IIcis boot fine without a battery installed. It's true that some of the other II series Macs won't boot with a battery, but the IIci should be fine without one. It is kind of weird that your battery is already down to 2.5V and it's brand new, though -- very odd.

I had a similar problem with my IIci that hasn't been recapped yet -- it was gunk on the motherboard near the power circuit causing it. After I blew some compressed air on the motherboard near the power circuit it started working again. Since you just recapped and washed it, it's probably not gunk -- but it is probably something in that area of the board. I would double-check for anything weird (gunk, corrosion, loose solder joints) on the area of the motherboard below where the power supply goes -- that's where the power-on circuit is.

When I was having that same problem, Dennis Nedry pointed out if I had fried the CPU for example, the power supply fan should still come on. So since your motherboard is doing *nothing* at all, it's very likely that the problem is in the power circuit, and less likely that you have zapped any ICs or anything like that.

 

[Unknown_K]

Make sure you have the polarity of the new capacitors correct.

 

[Dennis Nedry]

I agree with Unknown_K. If you are installing surface mount tantalums, the line on them means positive.

The IIci does NOT require a working battery to turn on.

I would recommend pressing on your new capacitors as you press the power button, particularly the ones nearest the power supply connector. Sometimes they look soldered but actually are not making contact. You may need to remove the logic board from the IIci and carefully attach the power supply to it in order to be able to touch the caps as you press the power button.

 

[AppleMacintosh]

I actually removed and resoldered all the caps in the area. Nothing. One of the solder pads looks a little smaller than it should be as though part of it is gone or lifted. The solder sticks to the remnants fine but I'm curious if it's actually making contact with the trace.

 

[Dennis Nedry]

That's possible. Do you have a tester so you could follow the trace and test the connection between the cap and whatever it connects to?

 

[AppleMacintosh]

Yes I have plenty of test equipment. It looks like this particular trace is hard to see. I may have to break out the magnifying glass and spend a little time with it. I wish I had a functioning IIci board so I could compare.