BOMs for Quadra 950

[crmccluskey]

Hello all,

I have a couple Quadra 950s I want get running, and sooner or later I'll need/want to recap the PSU and mainboards. Anybody out there have any modern capacitor BOMs for the PSU and/or mainboard? If not I'll make some on DigiKey or Mouser and post them here once qualified.

I already know that one of the mainboards has a bad reset switch (the partner to the programmer/interrupt switch). Anybody have a line on where to get these old switches (or a modern replacement)?

Thanks,
Chris

 

[joshc]

The logic board capacitors in the Quadra 950 are tantalums from the factory, so they don't tend to need replacement unless they fail.

 

[Unknown_K]

Most of a IIfx (except for a couple in the startup circuit), Q650, and Q950 boards are all Tantalums and if they go bad they short and explode (hard to miss).

As far as power supplies go you probably just need to replace a few if it stops working. On a MDD PS I have I removed quite a few capacitors and the only one I found so that that's bad is a tiny .47uf 50V capacitor. Some caps are worked hard others are not.

 

[joshc]

@crmccluskey Something to bear in mind with the Quadra 900/950 PSUs is that they are known to be a bit 'fragile' and it is recommended to use them with a power strip with switches, so that it's plugged in on both ends before power is applied.

 

[markfendley]

@crmccluskey Something to bear in mind with the Quadra 900/950 PSUs is that they are known to be a bit 'fragile' and it is recommended to use them with a power strip with switches, so that it's plugged in on both ends before power is applied.

Hi @joshc - I would attest to this - mine is doing the same as in https://68kmla.org/bb/index.php?threads/quadra-950-power-on-and-off-after-a-few-seconds.37717/ - switching on for a second whilst hissing then going off again. This started happening after I fumbled to put the power cable in which was connected and switched on.

I have started taking the PSU apart and it sounds like the hiss is coming from the transformer labelled T1 (although I have yet to verify this for sure). I shall start replacing capacitors to start with...