IBM fixed disk controller cap replacement

[RetroSpector78]

Hi,

I have an IBM 5170 with an IBM fixed disk controller card that prevents the computer from starting.



I would like to replace the 2 caps C45 and C46. I believe these are 22 uF, 15V capacitors by Kemet ("bullet" type tantalum cap ?) (looks like this : http://www.bgmicro.com/22uf-15v-20-tantalum-capacitor-by-kemet.aspx)

Can I replace these with a more common tantalum cap like this 22uF 16V cap ?

 

[T-R-A]

Shouldn't be a problem. Make sure you observe correct polarity when replacing. As long as a capacitors stated voltage is equal or greater (up to a point), then it theoretically should work.

 

[RetroSpector78]

Is there a specific reason they used radial caps for those ? Or is such a decision purely based on the PCB design / layout / spacing between components ?

 

[T-R-A]

Most designs are largely influenced based on cost. At that time, the likely requirements were cheaper with an radial capacitor than a axial one. The next highest priority is usually real-estate (space available) but that board doesn't look very crowded, so it likely wasn't much of a concern. And finally, commonality (often the most important factor) is likely as well. Just like when Ford built the original Mustang out of mostly Falcon parts, if the part existed on another assembly, it'd be logical (and likely cheaper overall) to use it again...

 

[Chuck(G)]

Given the values, I suspect a plain old electrolytic will do just fine.

 

[T-R-A]

And there's no reason you couldn't replace radials with axials (or vice-versa) either, as long as the leads are long enough and there's not any issue with clearance.