68kMLA Classic Interface

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Which component to replace LL1 on 630-0525 Classic II analog board?
Posted by: joshc on 2020-04-04 14:53:03 Which component should I order to replace LL1 on 630-0525 Classic II analog board? I hastenly removed LL1 along with all electrolytic caps, in hindsight LL1 could've stayed I think and I can't find any reference anywhere of what to replace it with! No obvious markings on the component itself.
Posted by: joshc on 2020-04-05 23:18:08 OK, so according to Larry Pina's Classic Mac Repair book, this is the 'Linearity Coil'. They don't seem easy to come by, I assume because they are only needed for CRTs: https://newly.en.ec21.com/Horizontal_Linear_Inductor_Coils--1949388_1949720.html I will probably solder the one I removed back on...
Posted by: trag on 2020-04-06 18:41:42 That's probably your best plan. If that is the component I think it is, (adjustable ferite core in center) then we looked at fabricating replacements for the Plus and earlier and the SE family and while it's probably doable it would be a bear. And I'm not sure we could match the impedance just right. For a start, it seems to be impossible to find ferrite cores of same diameter and length any more. Add to that that ferrite apparently comes in different grades adn we don't know what Apple used, and it just gets to be a nightmare. The wire in the coil isn't simple insulated wire. It's (IIRC) Misch wire, which is several individually insulated strands bundled into each apparent strand. What guage and strand number they used for that is another resolvable, but challenging issue. Reproducing it would be a lot of effort for something that just doesn't need replacement very often.
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