JDW
Well-known member
I tend to swap out the electrolytics in a recap and leave the film or metalized paper caps alone if they are good. Some among us have experienced blown filter caps near the power input on the original Macintosh analog boards, specifically these Rifa caps:
C33: 4700pf 250VAC Minibox (sometimes found to be 2200pf?)
C37: 4700pf 250VAC Minibox (sometimes found to be 2200pf?)
C38: 0.1uF 250V Minibox
The stock Rifa caps all appear to be metalized paper capacitors. A directed replacement for C33 and C37 would be the KEMET PME271YA4470MR30, also metalized paper. But would a Polypropylene version safety capacitor like the WIMA MKY22W14703F00KSSD be a better choice? There is also the KEMET F462AG472J1L2A polypropylene cap, but it is not classified as safety and therefore I do not know if it's failure mode would be open circuit when it blows. Similar thinking should apply to replacements for C38.
Please let me know your thoughts.
Thank you.
C33: 4700pf 250VAC Minibox (sometimes found to be 2200pf?)
C37: 4700pf 250VAC Minibox (sometimes found to be 2200pf?)
C38: 0.1uF 250V Minibox
The stock Rifa caps all appear to be metalized paper capacitors. A directed replacement for C33 and C37 would be the KEMET PME271YA4470MR30, also metalized paper. But would a Polypropylene version safety capacitor like the WIMA MKY22W14703F00KSSD be a better choice? There is also the KEMET F462AG472J1L2A polypropylene cap, but it is not classified as safety and therefore I do not know if it's failure mode would be open circuit when it blows. Similar thinking should apply to replacements for C38.
Please let me know your thoughts.
Thank you.