(Topic ID: 238086)

Proto F-14 Tomcat - Blown fuse after Q33 issue / U20?


By baseraider

9 months ago



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  • Latest reply 9 months ago by wayout440
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#1 9 months ago

Proto F14 Tomcat here.

Transistor at Q33 recently blew after coil locked on.

Now if power is turned on; the fuse highlighted in the reference picture shows continuity to ground at right side. I noticed continuity to ground on pins 1J11-4 and 1J11-5 also. These conditions are only with power on.

Replaced the coil associated, Q33 and its pre-driver.

Since these all tie back to U20...Im assuming the 7408 @ U20 is most likely bad.

Any thoughts? Thanks in advance

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