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Electronics => Projects, Designs, and Technical Stuff => Topic started by: Refrigerator on October 11, 2019, 08:31:04 am

Title: What value is this capacitor?
Post by: Refrigerator on October 11, 2019, 08:31:04 am
I found a cracked cap in my SAAB DIC and would like to replace it before i get a new DIC.
I think it's a 1µF 630V poly cap but i'm not sure and would appreciate some input.
[attach=1]
Title: Re: What value is this capacitor?
Post by: tautech on October 11, 2019, 08:38:18 am
I found a cracked cap in my SAAB DIC and would like to replace it before i get a new DIC.
I think it's a 1µF 630V poly cap but i'm not sure and would appreciate some input.
(Attachment Link)
Yep that's how I read it too plus J tolerance.
Title: Re: What value is this capacitor?
Post by: MagicSmoker on October 11, 2019, 09:58:47 am
Yep, it's a 1uF/630VDC/5% film cap likely made by TDK/EPCOS (blue color)... BUT... what could have caused a film capacitor to fail from what looks like internal overpressure? That's something you might expect that to happen to a heavily abused elko, not a film type, so if you are going to go to the trouble of depotting the module to replace the capacitor you should do a little more investigating to see what could have caused it to fail so spectacularly.



Title: Re: What value is this capacitor?
Post by: Refrigerator on October 11, 2019, 10:26:46 am
Yep, it's a 1uF/630VDC/5% film cap likely made by TDK/EPCOS (blue color)... BUT... what could have caused a film capacitor to fail from what looks like internal overpressure? That's something you might expect that to happen to a heavily abused elko, not a film type, so if you are going to go to the trouble of depotting the module to replace the capacitor you should do a little more investigating to see what could have caused it to fail so spectacularly.
I just carved out the old cap and soldered on a new one to the legs of the old one, no way am i depotting the whole thing because it's rock hard epoxy.
The DIC was made in 1998 and is bolted to the top of the hot cylinder head so i think that counts as some pretty good abuse.

There have been plenty of bad X/Y class caps that split open, most made by RIFA.  :box:
Title: Re: What value is this capacitor?
Post by: MagicSmoker on October 11, 2019, 10:34:30 am
I just carved out the old cap and soldered on a new one to the legs of the old one, no way am i depotting the whole thing because it's rock hard epoxy.
The DIC was made in 1998 and is bolted to the top of the hot cylinder head so i think that counts as some pretty good abuse.

There have been plenty of bad X/Y class caps that split open, most made by RIFA.  :box:

Oh, this thing is bolted to a hot engine? Yes, that certainly counts as abuse and so I'd agree this is likely a similar failure mode to those (infamous) Rifa "safety" capacitors - epoxy molding splits open and lets in water vapor that eventually does the poor capacitor in.