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geekhack Projects => Making Stuff Together! => Topic started by: hokie1991 on Sun, 07 February 2021, 11:34:02

Title: Model M SSK Repair
Post by: hokie1991 on Sun, 07 February 2021, 11:34:02

So I have this SSK Model M I acquired - (Untested) which I think i know why.  Anyway kid and I did a screw mod and everything is in good shape.  in looking at the circuit board I saw this (picture attached)  of one of the capacitors.  I think this is a capacitor like this:

https://www.ebay.com/itm/1000-PF-50V-MONOLITHIC-CERAMIC-CAPACITORS-100-pcs/172143589280?hash=item28148eb7a0:g:rrEAAOxy8F1RGHUt

I have not really been able to find a circuit diagram of the SSK Model M 1392934.  I thought about plugging it in to test as we have not done that yet... but I dont know enough tons about circuits  and I am thinking if that capacitor was in there... it had a purpose.

I would like to test the rest of the parts on the board as I can with a multi meter, and a diagram would be very helpful for this.  I could sent it to Unicomp to fix, but that seems like cheating and it is a good project for a teenager anyway. 

Any advice or know where I can find a circuit diagram for the ssk PCB?

Thanks

I fixed one old Model F that needed a new capacitor and got a lot of help on this site.

Title: Re: Model M SSK Repair
Post by: feltel on Thu, 11 February 2021, 07:30:36

I would just replace those cap and the board should work again. It looks like it was destroyed by mechanical force rather than any electrical fault.

Title: Re: Model M SSK Repair
Post by: yui on Thu, 11 February 2021, 09:48:03

likely it had a purpose when computer power-supply were much noisier, the M do not really need capacitor in its operation, at least i do not think, you will not fry anything by trying it out like that, and really any 102 capacitor should be able to replace it, when those fail they usually short and would catch on fire if across high current traces, not happening in a model M, it got hit and it ripped one of the legs, easy to fix and should be the only issue :)

Title: Re: Model M SSK Repair
Post by: micmil on Sat, 13 February 2021, 22:26:10

The purpose of the caps likely won't change all that much from one Model M to another. On the schems I've seen the only thing they're for is noise filtering. It should operate fine without them, but replacing with a same value cap would be ideal. The ones you show from eBay would work without issue.