| Electronics > Repair |
| Nichicon Electrolytic Capacitors leaking - common problem? ( Rifa X and Y also) |
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| precaud:
I recently rebuilt two DACs, same model. Going by the serial numbers and component date codes, they were made about 6 months apart - late 1999 to early 2000. Both had ten 100uF 16V Nichicon lytics of the new-style construction. In the earlier unit, all ten had leaked and made quite a mess. In the later unit, they were all fine. |
| Jay_Diddy_B:
Hi group, Here are some pictures from one of the phenolic-based electrolytic capacitors. It is a Nichicon PR(M) 1000uF 50V pulled from a power supply with serial starting 3215A. I estimate this to be 1992 production. Teardown I have torn away the aluminum case to reveal how the can to base is sealed. This is with the core removed from the aluminum case. I suspect the seal that failed is around one or both pins. The out seal is well crimped during the construction. This is the inside of the rubber seal. This is the outside of the base. I tried to separate the phenolic from the rubber and I was unable to. Regards, Jay_Diddy_B |
| Jay_Diddy_B:
Hi groups, The second HP 6671A that I removed the capacitors from was branded HP or the front Agilent on the serial number label. Agilent started doing business on November 1st 1999. The serial number starts MY 4100 so that is 2001. This had the new style capacitors. I am going to change the capacitor anyway since I have the unit apart. Have members seen the new style capacitor leak? Could it be that this problem was fixed in or around 2000? Regards, Jay_Diddy_B |
| Jay_Diddy_B:
--- Quote from: james_s on September 28, 2020, 04:13:09 am --- Snip ... I've had one of those RIFA capacitors burn up once too but again it was over 30 years old so I don't really buy into the "RIFA caps are crap" thing, they just have a finite life like many other parts. The one Schaffner filter I opened up didn't have RIFA caps in it, it had more modern looking blue ones with an epoxy fill. Snip ... --- End quote --- I am not sure that I buy the argument that the Rifa capacitors are crap either. At the time the Rifa capacitors were very widely used and regarded as the 'gold standard' in in EMC capacitors. I think that some of the reputation comes from the position in the circuit. They are connected either from line to neutral or from line (or neutral) to ground. They are exposed to large transients and high fault currents. Unless I see some evidence of distress, like a cracked case, I am tempted to leave them alone. Comments? Regards, Jay_Diddy_B |
| wraper:
--- Quote from: Jay_Diddy_B on September 28, 2020, 01:14:05 pm ---I am not sure that I buy the argument that the Rifa capacitors are crap either. At the time the Rifa capacitors were very widely used and regarded as the 'gold standard' in in EMC capacitors. I think that some of the reputation comes from the position in the circuit. They are connected either from line to neutral or from line (or neutral) to ground. They are exposed to large transients and high fault currents. --- End quote --- They are crap and they crack even when NOS caps are just sitting in a box. No other capacitor is known to crack and explode in flames in such application. They may lose most of capacitance due to shorting and self healing but none of them explodes except Rifa. |
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