G90 Repair

G90 Damaged RF Filter Toroid

A few days ago, I unwisely started moving things around to get ready to disconnect, before shutting off the radio. I was operating from a battery at the time, with fuses on the positive and negative on one cable (battery to powerpole) and a fuse on the positive only on the next cable (powerpole to g90's connection.) Something was loose enough that there was a short circuit, then a visible spark, a pop, immediate radio shutoff, and some smoke.

It turned out that the fuses closest to the battery were 30A, way too high for this application. The fuse closest to the radio was 10A, and it was blown. The negative side had no functioning fuse. Upon opening the radio I could see that the RF filter toroid next to the power into the main/lower PCB was visibly damaged, with one of the wires burned through. No other damage was visible. On groups.io I learned that the short had probably put voltage on the negative side, and the RF filter had essentially acted as a fuse.

Unable to locate a replacement part, I went ahead and desoldered and disassembled the wrapped toroid, after taking photos. I unwrapped it, measured, and re-wrapped it. I used 8" of 22awg enameled copper wire to create 8 turns ccw (there was excess, which I trimmed to size), to match the original. I soldered the repaired part on and re-assembled the radio... and everything is working great again! Tested digital and phone on multiple bands.

G90 Repaired RF Filter Toroid

The moral of the story is: use the right fuses and use them on both the positive and negative sides, and be careful of shorts! I'm pleased that the radio survived this little mishap, and was easily repairable.

G90 Burned Toroid
G90 Rewrapped Toroid

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