Capacitor replacement on a VP22 Mainboard (16902a Logic Analyzer) - Short HowTo

[DocBen]

You will need:
- the service guide for the 16902a (if thats where your vp22 lives) to get a lay of the land

- capacitors:
6x 1500uF 6.3V 105°C caps (while your at it might as well be Low ESR) - for example Panasonic FR series or Yageo SC series depending on your budget
2x 1000uF 16V 105°C
1x 680uF 6.3V 105°C polymer capacitor 6SEPC680M (dont be fooled: these things have about ten times the ripple current of low esr electrolytic caps -> much smoother output current)
all 5mm lead spacing, any diameter <= 10mm should be fine

- some kind of soldering tweezers because the caps are soldered to power planes without thermals.
- a desoldering pump is quite handy

- scalpel with a sturdy handle to cut the elastic between the capacitors and under them where it touches the board, otherwise it is very difficult to remove the capacitors, this stuff really doesnt want to let go.

disassembly is hindered in a few places:
both the motherboard and the pci/backplane connector card are held in place by a metal stub. I needed to compress it slightly to get them free (and remove the screws of course)
all the standoffs of the mainboard i/o connectors are screwed through the rear panel, so you have to remove those too before you can remove the board

the rest is easy: remove old caps, solder in new caps, reverse dismanteling, power on and pray nothing explodes. done.