In Reply to message #367923 by sh3rman
Member Member jerleeb is not online, or is invisible.
10/19/2015 5:42:38 AM
jerleeb Member #: 101781 Registered: 5/20/2015
Posted: 2 View all posts by jerleeb
Location: United States
Re: Fuses Keep Blowing
finding partial shorts are the worst!! I have a few ideas that may speed things along:

1. Assuming the amp has more than one leg, start by ohming each one individually. This is easily done by pulling the faceplate of the first passive outbound and checking the resistance on the pins. Calculate the design resistance as built by using the coefficients for cable, passives.

2. TDR each leg to look for problems. You are looking for a downward deviation in the trace. Pay attention to all of them as partial shorts can simply be multiple "mini-shorts" combining into one BIG current draw.

3. Weather- Is this happening constanly or only sporadically? Heat causes expansion. During the day, long spans can have the center conductor expand up to 1/2". Over-length conductors can buckle and cause a short during the day then shrink back at night. Also, once shorted, the conductor will shrink back enough to allow a new fuse to be installed and work fine...only to reoccur the next warm day. Also, rain or dewy mornings can soak the cable and cause a short. Look for squirrel chew, cracked cable, kinked cable, etc.

Using the TDR will cut your time spent down immensely. I know this involves effort, but keep your subs happy and look like a hero and fix it!!

Good luck, brother...
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10/20/2015 1:21:17 PM