2006 Mac mini Possible fix for no power to logic board

[MacTech68]

I've been measuring the black/blue caps, but havent found a bad one.
The cap that was faulty was actually the same one as yours

What I do to bypass the smc, is I unplug the power, press and hold the power-button for 5 secs and then insert the powerplug whilst keeping the power-button pressed. Then I release and press the power-button a second time.
That causes the board to power on and the fan(s) start spinning at 100%.

It's a similair method to how it works for my macbook pro 2010. So my guess was that this method bypasses SMC, as the fans spin at 100%.

IIRC, that's firmware update mode. It should be safe since it stores a backup of firmware to load if the current version fails.

I'm wondering if your CPU is OK. Be careful removing the heatsink, since there are MANY reports of breaking the nylon clip pins that hold the heatsink to the motherboard. There is also a temperature sensor attached to the heatsink via a short cable to the motherboard. Have you upgraded the CPU at some point?

I really wish I could find the (ahem) 'schem' for this board.

EDIT: You should be seeing 18volts across the pads of the capacitor you removed.

 

[aart]

The plan was to upgrade the cpu, as it currently is a core solo 1,5ghz.
I removed the cpu before, cleaned it with proper alcohol and re-seated it (with new thermal paste of course). Hopefully I can identify if it's faulty somehow, maybe a pin bent in the process before. I will also get a new cpu to check. a t7200 is cheap as chips on ebay I noticed. Might take a while though.

I'm getting 18V across the board since the cap was removed, also on the pads. I take it a broken sata/dvd connection board or lead wouldnt cause a bootrom fail, or would it?
Thanks again so far anyway.

 

[MacTech68]

The plan was to upgrade the cpu, as it currently is a core solo 1,5ghz.
I removed the cpu before, cleaned it with proper alcohol and re-seated it (with new thermal paste of course). Hopefully I can identify if it's faulty somehow, maybe a pin bent in the process before. I will also get a new cpu to check. a t7200 is cheap as chips on ebay I noticed. Might take a while though.

I'm getting 18V across the board since the cap was removed, also on the pads. I take it a broken sata/dvd connection board or lead wouldnt cause a bootrom fail, or would it?
Thanks again so far anyway.

Even if the sata/interconnect board was bad, I'd still expect at least a startup chime (if you removed it), though I'm NOT 100% certain. The audio out jack and speaker/headphone switch are part of that board. Gee, that was helpful of me.

It really strikes me as odd that you've had a ceramic cap failure but removing it hasn't brought it back to life. Something doesn't add up. To have two failures at once doesn't sound right.

Have you checked the flexible PCB that plugs into the Interconnect board? They're prone to splitting if you bend them too much or they can tear across tracks. This cable comes from the small Audio board at the top rear of the machine.

 

[aart]

Even if the sata/interconnect board was bad, I'd still expect at least a startup chime (if you removed it), though I'm NOT 100% certain. The audio out jack and speaker/headphone switch are part of that board. Gee, that was helpful of me.

It really strikes me as odd that you've had a ceramic cap failure but removing it hasn't brought it back to life. Something doesn't add up. To have two failures at once doesn't sound right.

Have you checked the flexible PCB that plugs into the Interconnect board? They're prone to splitting if you bend them too much or they can tear across tracks. This cable comes from the small Audio board at the top rear of the machine.

Well I had good hopes in the fact that the cap was the only issue. The mac was given to me as dead, so I'm not sure what might have happened to it before it died.
I did check the ribbon cable, but it seems to be ok. I really hope it's the cpu that is fried. But, I can't check that until the new one arrives. Which will take a while.
Other than that, I can't see anything being wrong with the board.

 

[aart]

Result!
So, I took off the cpu cooler, and guess what, the cpu lock was not closed fully. I am such a bad technician...
I'm installing SL as we speak, thank you very much for the help so far Mactech68!

Up next is a proper cpu and flashing the firmware to 2.1. But that's all for the new year

 

[MacTech68]

Result!
So, I took off the cpu cooler, and guess what, the cpu lock was not closed fully. I am such a bad technician...
I'm installing SL as we speak, thank you very much for the help so far Mactech68!

Up next is a proper cpu and flashing the firmware to 2.1. But that's all for the new year

Great to hear. And don't worry, we all make a mistake now and then.

Enjoy!

 

[veeectorm]

Hi guys!

Ive been searching the forum, and this thread is the closest thing i got to whats happening to my mini.

its a 2006 1,1, core solo, 512 ,came with no hdd. I got it thru an ebay-like site down here in south america. It was supposed to be non working unit. I got it, plugged the thing in, and it posted and gave me the folder icon thing. Remember, it was supposed to NOT turn on.

So, i got a snow leopard usb, booted into that, checked specs on system profiler, blah blah blah.

I got an hdd, plugged it in, and now it wont boot or post at all. What it does is light up, fan starts spinning, and the heatsinks do get a bit warm....but thats all.

I think this might be a capacitor that is acting up, or something along those lines. Any input would be greatly appreciated!

Thanks.

V.

EDIT: Should've said, that i took the hdd out, and it still doesnt post. Just the white led. HDD works perfectly fine on another pc.

EDIT2: More info, taking out the ram, does not make the mini beep. I did try different sticks as well, one that i know for sure it works on my other mini. Ill probably wait a day or two, and see if it boots after that...which would be WEEEIRD.

 

[MacTech68]

Hi guys!

Ive been searching the forum, and this thread is the closest thing i got to whats happening to my mini.

its a 2006 1,1, core solo, 512 ,came with no hdd. I got it thru an ebay-like site down here in south america. It was supposed to be non working unit. I got it, plugged the thing in, and it posted and gave me the folder icon thing. Remember, it was supposed to NOT turn on.

So, i got a snow leopard usb, booted into that, checked specs on system profiler, blah blah blah.

I got an hdd, plugged it in, and now it wont boot or post at all. What it does is light up, fan starts spinning, and the heatsinks do get a bit warm....but thats all.

I think this might be a capacitor that is acting up, or something along those lines. Any input would be greatly appreciated!

Thanks.

V.

EDIT: Should've said, that i took the hdd out, and it still doesnt post. Just the white led. HDD works perfectly fine on another pc.

EDIT2: More info, taking out the ram, does not make the mini beep. I did try different sticks as well, one that i know for sure it works on my other mini. Ill probably wait a day or two, and see if it boots after that...which would be WEEEIRD.

Usually, these capacitors short. It permanently prevents the external power supply from powering up (a feature of SwitchMode Power Supplies).

I'd suspect something to do with the CPU, much like aart had above.

If the White LED on the front is coming on then you're getting 18Volt power from the external AC Adapter to the logic board and the particular capacitors are probably NOT the fault.

When it DID power up, what CPU was in it? Maybe the previous owner attempted to upgrade the CPU and messed something up. The plastic heatsink clips are easy to break and maybe the heatsink isn't seated correctly and/or the CPU isn't fully in the socket.

If it doesn't appear that there's anything amiss with the CPU and it's installation (including the CPU heatsink temperature sensor), then it's going to be an uphill battle. If you can borrow the same model external AC Adapter, that will rule out the AC Adapter.

Other than that, try removing the Airport card and the bluetooth card - just to 'minimize' your configuration.

Finally, in case you don't have it. try searching google for : "mac_mini_early_late_06"

 

[veeectorm]

Usually, these capacitors short. It permanently prevents the external power supply from powering up (a feature of SwitchMode Power Supplies).

I'd suspect something to do with the CPU, much like aart had above.

If the White LED on the front is coming on then you're getting 18Volt power from the external AC Adapter to the logic board and the particular capacitors are probably NOT the fault.

When it DID power up, what CPU was in it? Maybe the previous owner attempted to upgrade the CPU and messed something up. The plastic heatsink clips are easy to break and maybe the heatsink isn't seated correctly and/or the CPU isn't fully in the socket.

If it doesn't appear that there's anything amiss with the CPU and it's installation (including the CPU heatsink temperature sensor), then it's going to be an uphill battle. If you can borrow the same model external AC Adapter, that will rule out the AC Adapter.

Other than that, try removing the Airport card and the bluetooth card - just to 'minimize' your configuration.

Finally, in case you don't have it. try searching google for : "mac_mini_early_late_06"

Well, i did try the PSU with another mini, and it works great.

The weird thing, is it only stopped working when i plugged in an HDD. Before that it was working GREAT, i got into system profiler (from SL install disk) and checked the specs and all.

Im thinking that maybe the prev owner let it rest for some time, something discharged and it started working again. When i plugged the disk in, it triggered the same problem, and now its not booting again. Maybe if i let it rest for some time, it'll come back to life again. Its one of those weird situations.

I did remove ALL but ram and cpu to isolate the issue, and its doing the same thing. Also, i let the thing rest for a day without plugging it in, but its not coming back up...so i guess im letting a week go by to see if i can make it work. Ill keep you guys posted!

 

[rubli]

shorted cap found ! but no 5 Volts

Thanx for sharing your experiences, thanx to the posts here, I was able to find a shorted cap (on the 18 volts rail), but I do not have 5 volts.. any hint how should I tackle this problem ??

thanx

A Rubli

 

[MacTech68]

Thanx for sharing your experiences, thanx to the posts here, I was able to find a shorted cap (on the 18 volts rail), but I do not have 5 volts.. any hint how should I tackle this problem ??

thanx

A Rubli

What does the machine do when you attempt to power on. And how/where are you determining that a 5 volt rail is down?

There may be more than one 5v rail if other mac motherboards are anything to go by.

Sadly, there seems to be no schematic for this model available, so it's difficult to pinpoint where to look.

 

[rubli]

no 5 v

What does the machine do when you attempt to power on. And how/where are you determining that a 5 volt rail is down?

There may be more than one 5v rail if other mac motherboards are anything to go by.

Sadly, there seems to be no schematic for this model available, so it's difficult to pinpoint where to look.

thanx..

As I connect the power, the disk spins, the main voltage is still 18something, but no light at the led, and there are about 2.3 volts at the usb connector, no chime and no other signs of life....
I might put an external 5 volts to test, but am sure there are more different voltage suplies on the board

 

[MacTech68]

thanx..

As I connect the power, the disk spins, the main voltage is still 18something, but no light at the led, and there are about 2.3 volts at the usb connector, no chime and no other signs of life....
I might put an external 5 volts to test, but am sure there are more different voltage suplies on the board

If the HD is spinning then there is 5V on one of the 5V sub-rails. USB won't give you 5 volt until it is initialized.

Check your CPU mounting is correct.

 

[JoelBolan]

Hi I'm looking for the value of the capacitors and one resistance of a logicboard from a Mac Mini 2.1
See the picture, The capacitors and resistance are in red!
Thanks a lot for your help

Joel

 

[louisb60]

Hello
I have a Mac mini 2007 and a working psu
I have a big problem, when i Power up the machine the led lights up for 3s ans then shutdown the fan dont spin no hdd. I try à lot of working RAM change CPU removing everything even without RAM and CPU but doesnt work,the led lights up and shutdown.
I remove one bad capacitor near airport card
If someone can help me please
Thanks à lot
(Sorry for my english i am french)

 

[aurora72]

So how to isolate which one is bad? Take a lab power supply and connect the black side to a common ground and the red side to the positive side of one of the capacitors. Very slowly sweep the voltage from 0 to ~5V. In between steps use your fingers to detect heat from the capacitors. The bad ones will heat up significantly. Remove them and the system should start right up.

Is that lab power supply absolutely necessary? If we applied directly 5V into the capacitors, would they go defect? I ask because I have a not powering up Mac mini G4 whose capacitors I need to test and I don't have a lab power supply.

 

[MacTech68]

Is that lab power supply absolutely necessary? If we applied directly 5V into the capacitors, would they go defect? I ask because I have a not powering up Mac mini G4 whose capacitors I need to test and I don't have a lab power supply.

No, it isn't. You can use a plug-pack/wall-wart AC-to-DC adapter, BUT it needs to be a Linear plugpack and DC output. Linear plug-packs are the older, heavier types, rather than the SMPS (Switch Mode Power Supplies). SMPS are designed to shut themselves down if their output is shorted.

I've recently done the same evaluation on a Early 2009 Mac Mini. I used an old Netgear 12v DC, 1 Amp brick and found C8472 to be the culprit (these are much smaller 0805 sized).:

Only took about 20 seconds to heat it up enough to give my finger a minor burn to the touch. I wouldn't leave it connected for too long - I ran it in bursts of about 10 - 15 seconds.

Replacement was a Murata GRM21BC71E106KE11L 10uF 25V - the only 0805 I could access at the time (I would have preferred a 35V but they were on a long lead time).

 

[aurora72]

You can use a plug-pack/wall-wart AC-to-DC adapter, BUT it needs to be a Linear plugpack and DC output. Linear plug-packs are the older, heavier types, rather than the SMPS (Switch Mode Power Supplies). SMPS are designed to shut themselves down if their output is shorted.

Thank you for the reply. I have such AC2DC adapters (which have heavy transformer coils inside) and one of them has adjustable voltages of 3V 4,5 6V up to 15V increasing in 1.5V steps. I have tried using 4.5V to be safe. I've hold the positive end for about 20 seconds on 4 capacitors at the back and 4 capacitors on the front side of the board. But none of them gave my finger any sensible burn when I held them with my finger tightly.

Here is a pic showing my setup.

I will repeat the test with a laser device this evening. I will borrow the laser device from a friend. I think it will show the temperature increases more precisely.

I wonder if I can increase the voltage to 6V, 9V or 12V without burning any part on the board. Because you've said you used an old Netgear 12v DC brick I assume you've applied 12V on the capacitors, way more than the suggested 5V on the original post. So may I assume that 12V doesn't harm the capacitors or any other part on the board?

Meanwhile no +/- sign is printed on those tiny capacitors and both sides look the same. I can determine their polarity as they stand on the board by checking with the Ohm meter with one end connected to the board's ground. But I can't determine it if it's free from the board. How do you determine the polarity of those tiny capacitors when it's free from the board?

 

[MacTech68]

The best method I can suggest is to find a tantalum capacitor that gives the appearance of being shorted (when measured across with an ohm meter).

I then attach the negative & positive leads to the tantalum cap (the striped end is positive or is marked with a '+')

I usually solder the leads of the linear power supply to the tantalum cap, which allows you to quickly search the board top and bottom for the 'hot spot'.

Here are the Tantalums on the top side. Check if any seem shorted.

 

[aurora72]

Thank you for the comment. I've tested all the tantalum caps shown in the figure. Unfortunately they all worked properly i.e. no beeper sound came from my Voltmeter (Ohm meter) Just one of them gave the beeper sound, the one on top right, close to the power socket. But I have the same Mac mini G4 which works, and when I checked the same cap on it, it gave the beeper sound too so it must be designed to conduct electricity I guess. I've checked one or two tantalum caps at the back of the board and they too seemed to work properly.

After all the checking, I've plugged the power in once more to check (to see if some miracle happens but it didn't power up at all. The board is dead as a dodo I haven't given up all hopes though. I believe this board will power up if only I could determine the culprit. I'll keep on searching. I'm open to all suggestions.

 

[MacTech68]

@aurora72

By any chance have you checked the fuse on the logic board? Circled below, you'll find the fuse's two pins on the underside. Should be zero ohms. Seems like the G4 mini is the only mini with a logic board fuse.

 

[aurora72]

Thank you for the comment. I didn't know there was a fuse on the board. I've just checked it and didn't conduct electricity. It's burnt, open circuit, how do you call it: It's defect. This fuse must have been the culprit.

I've tried to remove the fuse but it just didn't come out. Then I've noticed that it's got a cap on it. I removed the cap and salt like particuls scattered around from it. There was a wire inside which was ruptured. I've made a short wire by twisting 3 copper tiny wires and soldered onto it. I've plugged in the power brick and it finally powered up! The white LED turned on and display turned on too but the picture is scrambled

Because I couldn't see the desktop I turned it off by unplugging the power chord. It operated about 2-3 minutes. No overheating of any parts and no damage to the power brick. But the display picture is scrambled. I guess this is caused by some staining on the board where Video RAMs are located:

Some discolorations around the soldered pins are visible. I wonder if this can be repaired by heating it with a heatgun to renew the soldered sections. I have a heatgun and laser temperature meter i.e. I can do that kind of repair.

 

[MacTech68]

Looks like corrosion. The vias are also suspect. That area is directly under the ATI video chipset.

Can it be repaired? Yes. Does it require specialized equipment and skill ? Yes.

Is it worth it for a G4 MacMini, probably not.

If you want to replace the fuse, it's a 5 Amp TimeDelay type by BelFuse. PN 0697A5000-01

0697A5000-01 - FUSE, RADIAL, TIME DELAY, 5A, 250VAC

Fuse Current:5A; Voltage Rating VAC:250V; Product Range:RSTA Series; Voltage Rating VDC:63V; Blow Characteristic:Time Delay; Fuse Case Style:Radial Leaded; Breaki 48AC8512

tr.farnell.com

 

[aurora72]

Looks like corrosion. The vias are also suspect. That area is directly under the ATI video chipset.

Can it be repaired? Yes. Does it require specialized equipment and skill ? Yes.

Is it worth it for a G4 MacMini, probably not.

If you want to replace the fuse, it's a 5 Amp TimeDelay type by BelFuse. PN 0697A5000-01

0697A5000-01 - FUSE, RADIAL, TIME DELAY, 5A, 250VAC

Fuse Current:5A; Voltage Rating VAC:250V; Product Range:RSTA Series; Voltage Rating VDC:63V; Blow Characteristic:Time Delay; Fuse Case Style:Radial Leaded; Breaki 48AC8512

tr.farnell.com

Thank you for the information. Under the time constraints of the time, I just short-circuited the ends of the fuse and it's been working quite fine. Let me shortly explain why it works fine. This Mac mini must have somehow caught some liquid or liquid vapor through the right bottom corner of the board where one of the 16MB VRAM chips is placed underneath and that liquid must have caused short circuit around the chip and that must have blown that fuse (5 Amp TimeDelay BelFuse) After the liquid was completely dried off, then the short-circuit around the VRAM chip must have gone. That's why it's working fine now, it's because there's no short-circuit anywhere around the board.

I've cloned a Snow (Sorbet) Leopard image into HDD and booted that Mac mini with it and it boots fine, operates the S. Leopard fine and it allows remote access over VNC clients. So I've accessed it over VNC and noticed that its Video RAM was 16MB which means that the affected VRAM chip doesn't get counted by the system at all. Here is the screenshot:

This suggests that the corrosion parts (tiny resistors & condensators) cause the video output to LCD display to cramble.

If that is the case, if I de-solder all those corrosion parts and the VRAM chip could I get a clean video at the LCD display with the 16MB VRAM ? If that is feasible, then I might take it to an experienced electronics repair technician I know and he could do that removal quite reliably.

 

[MacTech68]

...If that is the case, if I de-solder all those corrosion parts and the VRAM chip could I get a clean video at the LCD display with the 16MB VRAM ? If that is feasible, then I might take it to an experienced electronics repair technician I know and he could do that removal quite reliably.

Yes, it would but the other concern would be the vias - the round holes which are tracks that travel through the board making connections within the board and on the other side.

It's a lot of work and will probably require removing, cleaning, checking the ATI chip on the other side of the board.

However, if you have someone wiling to do it for a small fee and you know they are capable of this work, then yes, it might fix the missing 16MB VRAM (the G4 1.25Ghz model has 32MB VRAM) and the video output issue.