Broken Capacitors on CPU Board

[mgmtm3]

Just picked up a Mac Pro 5,1 2010 and went to upgrade the CPU's and on inspection I found that two of the capacitors are obviously not right. One is missing in the spot labeled CF403 and the other cap is bent and has one leg detached from the board on CF423. Oddly enough the computer works like a champ but I suspect there could be some long term issues power wise. First, does anyone know what these caps do on the motherboard and secondly is this fixable? Thanks!

 

[flyinmac]

Capacitors can be replaced with exact like model capacitors, if you are handy with a soldering iron.

I used to replace them on vintage hardware that I'd rebuild, just to make sure everything had a long life ahead of it.

As for what is affected by the specific ones on your board, I wouldn't know without doing some research on that board revision.

 

[mgmtm3]

Thanks for the quick reply, should I stop using the system until I can get it fixed?

 

[flyinmac]

Thanks for the quick reply, should I stop using the system until I can get it fixed?

It would be wise to not use any electronic equipment that has physically damaged electrical components, until the damage is repaired, or determined not to be potentially harmful. That would include disconnecting the power plug.

 

[Maxx Power]

By proximity, those capacitors form part of the Voltage Regulation Module (VRM) for either the CPU or CPU-related power needs. If they are not present, the regulation suffers. Depending on the exact role these capacitors play, you may have transient spikes in the supplied voltage to unstable voltage regulation that oscillates. Either way, it is best not to operate the system in its current condition. If these capacitors are downstream of the switching transistor - whatever part is supplied by these capacitors sees much larger than normal voltage fluctuations and will be eventually damaged. If these capacitors are upstream of the switching transistor and logics, those portions may be damaged through time. All estimates assuming worst case scenario.

Either way, these surface mount caps are super easy to solder. You just need to source one.

 

[mgmtm3]

Would anyone know where I could source these parts? I've tried the usual google routes and I'm coming up empty handed.

 

[Maxx Power]

Would anyone know where I could source these parts? I've tried the usual google routes and I'm coming up empty handed.

The best bet is (for your single usage), eBay and Amazon. Otherwise, electronic supplier companies are best for larger batches and combined orders - Mouser, Newark Online, Digikey, Farnell. However, the shipping is going to be more than the part, since you are getting just 1 or 2 capacitor(s).

Were you able to verify the brand and specifications of the caps ? They look like Sanyo OsCons of yester-year.

This store on eBay carries OsCons:

http://stores.ebay.ca/CircuitDIY/OSCON-/_i.html?_fsub=655669012

Make sure that the capacitors are surface mount (90 degrees flat legs and a plastic retainer at the bottom) and NOT through-hole (with straight long legs).

 

[mgmtm3]

That helps so much. The top of the capacitor has these numbers and letters.

046
PC
39
16
[doublepost=1479103768][/doublepost]I believe it might be one of these? I don't know much about capacitor ratings but it seems like the first or second listing just winging it off the capacitor markings. Am I on the correct trail here?

 

[Maxx Power]

That helps so much. The top of the capacitor has these numbers and letters.

046
PC
39
16
[doublepost=1479103768][/doublepost]I believe it might be one of these? I don't know much about capacitor ratings but it seems like the first or second listing just winging it off the capacitor markings. Am I on the correct trail here?

I believe the capacitors in your Mac Pro are the SVPC series, I have seen OSCONs marked like that. The last two numbers indicate the specifications - 39uF (micro-Farads) and 16V (volts). You just need to match the 39uF and 16V.

 

[flyinmac]

I believe the capacitors in your Mac Pro are the SVPC series, I have seen OSCONs marked like that. The last two numbers indicate the specifications - 39uF (micro-Farads) and 16V (volts). You just need to match the 39uF and 16V.

And also remember when installing them, that capacitors have a positive and negative. So watch for orientation as you install them.

 

[benjaprud]

Also these capacitors don't have a spot weak enough to allow them to inflate and open up from the top in case of aging failure. As a result these tend to slowly leak their electrolyte from the bottom. The electrolyte is corrosive and may slowly eat the surrounding traces. The copper traces then turn to black which is difficult to see on those black coated PCBs. Before replacing the capacitor someone has to check for bad contacts and corrosion, clean it and fix the damaged traces otherwise it will continue to spread. If it smells like bad fried fish when you unsolder the capacitor, it's a sign that it may have leaked.

I'd say this kind of intervention however simple it may look should be done by a trained professional, your local TV/HiFi service tech should be able to do it for a modest fee. Don't do it if you've never handled a soldering iron, you may just make things worse.

Now if you're lucky these have just received a shock following a bad manipulation which has broken the soldered joints. I'd say it's more likely as I've never seen a capacitor vanish or fall down the PCB on its own. In that case you just have to solder new ones in place which makes the intervention much easier. Just put them in the right direction otherwise they will blow up. The blue mark (or whatever color it is on your spare capacitors) indicates the negative pole which is at the bottom on your picture for both CF403 and 423.

 

[Maxx Power]

Also these capacitors don't have a spot weak enough to allow them to inflate and open up from the top in case of aging failure. As a result these tend to slowly leak their electrolyte from the bottom. The electrolyte is corrosive and may slowly eat the surrounding traces. The copper traces then turn to black which is difficult to see on those black coated PCBs. Before replacing the capacitor someone has to check for bad contacts and corrosion, clean it and fix the damaged traces otherwise it will continue to spread. If it smells like bad fried fish when you unsolder the capacitor, it's a sign that it may have leaked.

I'd say this kind of intervention however simple it may look should be done by a trained professional, your local TV/HiFi service tech should be able to do it for a modest fee. Don't do it if you've never handled a soldering iron, you may just make things worse.

Now if you're lucky these have just received a shock following a bad manipulation which has broken the soldered joints. I'd say it's more likely as I've never seen a capacitor vanish or fall down the PCB on its own. In that case you just have to solder new ones in place which makes the intervention much easier. Just put them in the right direction otherwise they will blow up. The blue mark (or whatever color it is on your spare capacitors) indicates the negative pole which is at the bottom on your picture for both CF403 and 423.

These are OSCONs, which means they are solid internally (dry electrolytic) and do not feature a wet electrolyte. OSCON are a type of conductive polymer solid capacitors. All polymer capacitors do not use electrolytes. The ones that do feature electrolyte are wet electrolytics and feature vents on top. These vents are supposed to deploy in a great majority of cases, but in some cases, the rubber sealing at the bottom is weaker and gives first, leaking a mess over the PCB.

As "flyinmac" added, watch the polarity when you install the capacitors (or have someone else do it for you), the stripped side is the negative. If in doubt, please check it up before attempting an installation.

 

[sevichenko]

try to solder new ones. japanese capacitors are the best

 

[mgmtm3]

Thanks everyone for the advice, I have found the parts and I will attempt the repairs with a friend who is a bit more skilled at soldering. Wish me luck!

 

[flyinmac]

Sounds good. Hope it goes smoothly.

 

[sevichenko]

good luck!!

 

[ActionableMango]

I hate an unfinished story, so let us know how it goes!

Don't be a G.R.R. Martin!

 

[benjaprud]

These are OSCONs

Thanks, I didn't know about those, they all look purple apparently for a reason

 

[Maxx Power]

Thanks everyone for the advice, I have found the parts and I will attempt the repairs with a friend who is a bit more skilled at soldering. Wish me luck!

May I recommend that you look at a tutorial before attempting it. For example, soldering a SMD capacitors (like yours):

.

If your PCB has had solder already applied, you absolutely need to clean the pads on the PCB (with a hot iron and desoldering wick), then clean it with alcohol swabs and apply flux to the pads on the PCB before soldering. The specifics vary a bit on methodology, such as applying flux. I prefer flux on the PCB before aligning and soldering, the video shows application of flux after part alignment, which I find more difficult because you have to hold the part while retrieving your flux pen. They both work.

 

[mgmtm3]

I hate an unfinished story, so let us know how it goes!

Don't be a G.R.R. Martin!

Promise I will tell the ending, good or bad.

 

[mgmtm3]

Mission Successful! Computer is up and running like a champ. it always was running but I fell a lot better about the future reliability of it now) I would like to thank everyone on this thread for all of your tips and help figuring out the type of caps used on this computer.

 

[flyinmac]

Glad to hear that it's up and running, and that the repair went smoothly.

I hope the computer provides you with many years of service.

 

[sevichenko]

congrats!!

 

[leoaf79]

By proximity, those capacitors form part of the Voltage Regulation Module (VRM) for either the CPU or CPU-related power needs. If they are not present, the regulation suffers. Depending on the exact role these capacitors play, you may have transient spikes in the supplied voltage to unstable voltage regulation that oscillates. Either way, it is best not to operate the system in its current condition. If these capacitors are downstream of the switching transistor - whatever part is supplied by these capacitors sees much larger than normal voltage fluctuations and will be eventually damaged. If these capacitors are upstream of the switching transistor and logics, those portions may be damaged through time. All estimates assuming worst case scenario.

Either way, these surface mount caps are super easy to solder. You just need to source one.

Hi, it's been a while since last post on this thread, but i'd like to know if this oscillations in the attached istats pictures are normal or should I inspect those capacitors.