68kMLA Classic Interface

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Missing inductor on Thunder 24 card

Posted by: rickrob on 2023-12-01 18:53:01 I picked up a Thunder 24 rev A card from eBay. Seller said it might be missing a cap on the back side. Got it today and the missing part appears to be an inductor. Just above the left side of the the three rows of pins in this pic are two grey inductors labeled L2 and L4. On my card, L4 is missing. Can anyone point me in the right direction to find a replacement? I have an LCR meter on order to find the value of L2, my guess is they are both the same value. There are no markings of any kind on them.

Posted by: bigmessowires on 2023-12-01 19:01:23 There's also L1 and L3 to the right of the connector, and L8 and L9 at the far left, and (in smaller packages) L5 and L6 at near left. That's a lot of inductors! I would guess they're there to help filter out high frequency noise from power supply rails and other DC signals. My prediction would be that all of the larger ones are the same value, but if they're for filtering then the exact value doesn't really matter. You would be looking for something similar to a ferrite bead as a replacement.

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