broken or missing diode on spare whirlwind board what do I need?

[David P]

This is just a spare board I bought off ebay for my whirlwind found a broken diode wondering what is It? what is needed to replace it?

Thank You

[mcdefjef]

should be in the manual:
http://mirror2.ipdb.org/files/2765/Williams_1990_Whirlwind_Operations_Manual_Br_With_Schematics.pdf


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[BloodyCactus]

someones had a go at that board, your going to have to replace that nice fat IC next to the blow diode too. what else is missing or has been removed?

[David P]

someones had a go at that board, your going to have to replace that nice fat IC next to the blow diode too. what else is missing or has been removed?

U41 and u42 I have replacements for both - the blow diode as your calling is just has a B beside it there are several all over the board same one with -B- next to I can't find this part in the manual on the CPU parts description it is not an actual part number..hmmmm

[BloodyCactus]

well the note on the schematic says "All capacitors with value 'B' are bypass capacitors with value of 0.1uf"

[David P]

well the note on the schematic says "All capacitors with value 'B' are bypass capacitors with value of 0.1uf"

Thank you after looking at this spare board not sure it is worth fixing it has been beat up pretty bad!

[iankellogg]

That looks like a bypass cap. If you want to replace it put in a 0.1uF 20-50V ceramic. It is most likely not required for the board to operate and is more of a best practices thing in board design.

[KJ4IPS]

Real quick, that is a bypass cap, it is used to filter out high frequency junk, almost every high speed IC will have one (CPU, RAM, ROM, PIA, and more) If an IC is populated, it's associated bypass cap should be present.
They should always be very close together. According to BloodyCactus they originally were .1uf (which is a pretty common value). If that IC is not going to reinserted, just desolder and remove the broken part, otherwise the IC can be reinstalled while the cap's replacement is on order, but you should still reinstall it eventually.