Need help with a part for SE

[stevep]

Well I did a really stupid thing and unplugged / moved an ADB wire while the SE was on. Now I have no KB or mouse. Dead Mac Scrolls indicates I blew a filter - Apple Part 155-0007-E. Mine has no E however.

Would anyone be able to help me source this chip? I googled the Apple P/N but didn't get far before loosing my way.

This is the SE I am returning to the double 800K FD configuration (it had a HD hack job, but I want it to be orignal), and I was testing it after the drive change. I suspect there are other issues as well which lead me to swap ADB ports. I don't want to give up on this one yet

 

[wally]

Tokin D-16C

 

[stevep]

Thanks Wally!

Any idea where to buy one or two? All I can find are places with $250.00 minimum orders...

 

[wally]

Never had to order one. If they will not send one engineering evaluation and qualification sample part to your chief engineer, you might have to procure a parts board and salvage a filter. According to the Guide to the Macintosh Family Hardware Second Edition, the SE, SE/30, II, IIx IIcx, and IIci use the D16-C or equivalent filter. I have seen an unmarked non-common mode filter on a IIci, looks like a multi-aperture square ferrite block with eight vertical holes and four inverted u shaped exposed wire straps of one turn each. So I think Apple had another filter that passed the emissions suppression requirements while not generating quite so much ADB disconnection inductive kick voltage that tends to short out the other filter design.

Before procuring a replacement EMI filter you could remove the one thought to be faulty, test it for opens and shorts, and temporarily strap across the board pads to see if you can get the keyboard and mouse to work again. If the ADB tranceiver chip or driver transistor blew you might need still other salvaged replacement parts.

 

[tomlee59]

Definitely follow Wally's advice to test the filter before going to the hassle of obtaining a replacement. Testing is very easy. The filter consists of four inductors in an 8-pin package. Check for continuity between each pair of pins whose pin numbers sum to 9 [i.e., 1-8, 2-7, etc.].

These filters are pretty low-tech and relatively hard to kill, so it's important to make sure that the filter is actually dead. If testing reveals that it is dead, do as Wally suggests and simply bridge across the dead inductor winding(s). If nothing else blew up, then your ADB should spring back to life. You can run it this way until you find a replacement filter.