IBM 5170
Fixed Disk and Diskette Drive Adapter
Capacitors C45 and C46


On this card, the first generation of the 'IBM Fixed Disk and Diskette Drive Adapter', capacitors C45 and C46 are a tantalum type of capacitor, of the value: 22µF, 15V

There are cases of either C45 or C46 going short-circuit, overloading the power supply, stopping the computer from powering on.  For the IBM 5170, not even the IBM power supply's fan will turn.  Remove the subject card, and the IBM 5170 then powers up (albeit with errror messages).

Do not assume that either C45 or C46 on your good card will one day become short-circuit.  I have two of the subject cards, acquired over 10 years ago, and C45/C46 have not failed.  (UPDATE: At April 2024, C45 failed on one card.)

If you do need to replace either C45 or C46:

• Observe correct polarity; negative leg into negative hole, and positive leg into positive hole.  On the subject card, per the photo below, the positive hole is marked with a '+'.
• In this application, consider the use of an aluminium electrolytic type of capacitor.  That is the type that has been used for capacitor C47.
• In this application, you can use a capacitor of a higher rated voltage, e.g, 16V, 25V, 35V, 50V.
• In this application, you can use something higher than 22µF.  For example, 33µF.
• To keep a short profile, ideally, use an axial style (one leg out of each end).  That will reduce the possibility of the capacitor touching an adjacent expansion card.