Help needed with PM 6100 floppy drive

[powermax]

Capacitor issues?

That's quite possible - the board still contains eleven ancient SMD caps, three of them are located near the FDD connector.

I'll try to replace these three caps first. What's the best replacement for them? All electrolytic caps are 47µF, 16V. Various Internet sources advocate the use of tantalum capacitors, although it comes with its own set of problems (bigger sizes, polarity, derating). Some people use modern SMD caps as well as radial electrolytic caps...

 

[Unknown_K]

I use the same types when I recap and new ones are pretty cheap to buy (and I have them in stock so when a problem comes up I can fix it before I lose motivation).

 

[powermax]

I use the same types when I recap and new ones are pretty cheap to buy (and I have them in stock so when a problem comes up I can fix it before I lose motivation).

Can those modern SMD caps be used as replacement for the old ones? Why do other people prefer tantalum caps instead?

 

[Compgeke]

Those can, but using a modern tantalum means the caps won't ever leak again. There's nothing stopping you from using those but just note, in 20 years you might be going down the exact same path again of needing to replace.

Tantalum can fail but they usually fail in a manner that destroys them physically (cracks and\or shrapnel). The up side is this doesn't damage the PCB. It also can take quite a while, I've had good tantalum caps in vacuum tube era gear.

 

[powermax]

There's nothing stopping you from using those but just note, in 20 years you might be going down the exact same path again of needing to replace.

To be honest, I doubt these boards will work longer than 10 years. Looking at the quickly progressing corrosion of my two PM 6100 logic boards, I'm sure they will start to fail here and there and I won't be able to prevent that. Let's think about a memory slot for a minute - if such a slot doesn't work anymore is it ever possible to replace it without destroying the PCB?

Plus, the fact that the CPU and several proprietary ICs like floppy controller or audio codec are already difficult to obtain and will quickly become completely out of reach in the near future...

Anyway, many thanks for the helpful information!