- Dec 6, 2011
- 1,630
I was helping a buddy get a piece of amateur radio equipment going last night. I installed an upgrade board for him which was more mechanical dis-assembly and reassembly than actual electronics work. I sent him home with it and it refused to fire up. Went over to his house and we spent the next two hours trying to figure it out.
The long story short is that he has a device that lets him conveniently access 12 V from his high current power supply (commercially available as a RigRunner). There were two open ports on it, each port has its own ATC fuse. We were seeing 12 V on the power cable but the device refused to power up. Plugging the upgraded equipment directly into his power supply got it to work so this really left us dumb founded. Until I leaned over the power strip and noticed a glow behind both fuses when we tried to use those ports. The RigRunner has LEDs to indicate a blown fuse. Pulled the first and it was obviously popped. Pulled the second and it looked fine but a check with the multi-meter showed it was open. The design with the LED lets the 12 V still appear on the port but is limited to probably a few microamps. Unfortunately I don't have a schematic for the RigRunner to see how they set that up. Fine, light a LED to tell me the fuse is blown but don't let me see 12 V at the port!
So don't rely on saying the fuse looks good and wonder why your device ain't getting power, CHECK THE FUSE WITH A METER! That's been said before on the Nation but here's a real life example.
Fortunately my buddy had a stash of ATC fuses and we got everything up and running.
The long story short is that he has a device that lets him conveniently access 12 V from his high current power supply (commercially available as a RigRunner). There were two open ports on it, each port has its own ATC fuse. We were seeing 12 V on the power cable but the device refused to power up. Plugging the upgraded equipment directly into his power supply got it to work so this really left us dumb founded. Until I leaned over the power strip and noticed a glow behind both fuses when we tried to use those ports. The RigRunner has LEDs to indicate a blown fuse. Pulled the first and it was obviously popped. Pulled the second and it looked fine but a check with the multi-meter showed it was open. The design with the LED lets the 12 V still appear on the port but is limited to probably a few microamps. Unfortunately I don't have a schematic for the RigRunner to see how they set that up. Fine, light a LED to tell me the fuse is blown but don't let me see 12 V at the port!
So don't rely on saying the fuse looks good and wonder why your device ain't getting power, CHECK THE FUSE WITH A METER! That's been said before on the Nation but here's a real life example.
Fortunately my buddy had a stash of ATC fuses and we got everything up and running.
