Broken capacitor off of drive power board on ReadyNas Pro Pioneer

[jbaird]

Ok - so, I was replacing a failed PSU in my ReadyNas Pro Pioneer edition and accidentally broke one of the capacitors (CA11) off of the PCB where the molex connectors for the drive connect.

How should I go about getting this repaired?  Should electronics shops be familiar enough with this type of thing to easily repair it?  Can the capacitor that broke off be re-used?

I'm guessing I shouldn't even try to power up the ReadyNas without this capacitor replaced, correct?

Here is a picture:

http://web.kywimax.com/~jbaird/IMG_6950.JPG

[FramerV]

Hi jbaird,

As far as I can tell it should be possible for repair. Might really best to consult an electrician about it. Capacitors are generally used to store electricity so if it didn't blow up I think the one that got removed can still be soldered back.

I am not really an electrician but I have seen some appliances with capacitor issues and electrical shops were able to fix them. So I think its still best to consult experts about it.

Regards,

[booboo59]

You should have that repaired, as the capacitor is likely there to a good reason (such as smoothing a signal or for the power line).  You cannot use the broken one as half of it was left behind on the board, but any competent electronics repair can source the part and fix it.  The capacitor is surface mounted but simple to change.  

The good news is that the way it broke off, it appears there's no damage to the underlying board.  

[Sandshark]

Based on the visible traces on the board, it's for transient/surge protection on the 3.3V SATA power line.  Since I know of no SATA device that uses the 3.3V, I believe everything will work just fine without it.  The early 4-bay units originally had those installed, but later ones don't (there is just an empty location for them).  I'm surprised they didn't do a cost cutting for the 6-bay units and remove them as well, but even my Ultra6Plus has them. 

The middle one (as oriented in your picture) is for 5V and the left one for 12V, so you got lucky.  All of them are mainly needed for hot swapping of the drives, anyway.  Standard SATA wired connections don't have them.  You will also note that one pin for each voltage has an inline resistor.  Those go to the drive connector pins that are a little longer, so engage first, and are for "pre-charging" during a hot swap.  Again, a wired connection doesn't have them (which is why you should never hot swap drives without an appropriate hot swap bay).

If you do want to replace it, please talk to an electronics technician, not an electrician.  The former deals with circuit boards, and the later deals with building wiring.  The numbering on the capacitor is nothing I am familiar with or can Google, so unless there is additional writing on the side that gives the value or a Netgear employee with access to the schematic will tell you the value, he will likely need to measure the capacitance on one of the others and guess at the voltage rating based on it being for 3.3V and the physical size.  The value can likely be read accurately in situ rather than having to remove another for measurement.  On the 4-bay units, the numbering is more typical and they are 100uF 25V electrolytics, which is a typical value for that use.  Since the 12V cap in your picture has a different part number from the other two, the 5V and 3.3V may be rated at 15V with only the 12V rated for 25V as a cost savings (you typically use a cap rated at least 2x the actual voltage), but 25V for all sould work fine.  Or, the capacitance could actually be different for some reason  You can buy 10 of the 100uF 25V for $1.65 on eBay. 

[jbaird]

Hi Sandshark,

Thanks for the detailed response!

Just to confirm, since the 3.3V SATA power line is not being used, it should be safe to use the ReadyNAS without replacing this cap?  If I do this, would you recommend that I try to carefully remove the broken cap base from the PCB before powering it on?

If I do replace it, it should be fine to just use a 100uF 25V cap, right?

Thanks again!

[jbaird]

Just an update - everything appears to be working just fine without the 3.3V capacitor.

[Sandshark]

Removing the base would make it less likely that something somehow shorted the leads.  But since you aren't likley to be doing anything in that area of the NAS with the power on, shorting it out is an unlikely scenario.

Given that it's not really doing anything, replacing with a 100uF 25V cap wouldn't help or hurt except to make it look pretty.  If it were one of the others, it would be best to measure and see what the right value is.  If I ever need to replace another supply, I'll try to remember to take some readings.

It would be a wonderful thing if Netgear would make schematics of the legacy systems available.  I have a SATA backplane from a 4-bay system where only 2 drives are recognized (which I find odd because with each channel havng discrete components, having the same thing happen to two but not all four is unusual), and others have had problems that cannot be diagnosed without a schematic.  Some may be too complex to just shotgun based on a schematic, but others may be easily fixed.