Icom R8600 Blown Fuse

[srletend]

I powered off my R8600 last night via the Power button. It's connected to an Astron 13.8v power supply (RS-20M) via the fused power cable. The power supply drives two other radios. I left the power supply and one of the radios (R75) switched on overnight.

This morning, the R8600 would not power on... Trouble-shooting led to a blown fuse on the black ground cord between the radio and the power supply. I'm new to using linear power supplies, but nothing like this has happened in the few weeks I've owned the R8600. Or any other radio I've had over the last 15 years.

Questions:
(1) Are there some obvious things (or not so much) I should check to ensure there are no issues with the radio-power supply connection?

(2) I have no idea why a 3 amp fuse would have blown... I have not seen the power supply ammeter ever go above 2.1A (when driving all three radios)--any ideas for what may have caused a blown fuse?

 

[ve3ext]

try a second fuse., if it blows then there is definitely an issue
Let us know., for the next steps
Jerry VE3EXT

 

[srletend]

I replaced the fuse with the spare from Icom in the original box. Working fine the last few days but still wondering what could have caused the overcurrent???

 

[N8YX]

Ground loop between the negative lead and some other "ground" such as a coax shield.

Is the negative lead of all equipment in the shack common to one point, or is it distributed (as with usage of multiple Rig Runners)? How about chassis grounding of all equipment?

 

[srletend]

Here's the setup:

Astron PS rear red/black posts to red/black R8600 and Uniden SDS200 with separate fused cables
Astron PS front powerpole red/black connector to R75 DC Power jack without fused cable (9ft run)

The R8600 chasis ground screw connected to the Astron PS ground screw; Astron has typical 3-prong 120V A/C to wall outlet.

The R75 did have a separate ground going to the ground terminal next to the Antenna 2 terminal; this ground ran to a copper water pipe in the house.

 

[Willy_Pete]

I powered off my R8600 last night via the Power button. It's connected to an Astron 13.8v power supply (RS-20M) via the fused power cable. The power supply drives two other radios. I left the power supply and one of the radios (R75) switched on overnight.

This morning, the R8600 would not power on... Trouble-shooting led to a blown fuse on the black ground cord between the radio and the power supply. I'm new to using linear power supplies, but nothing like this has happened in the few weeks I've owned the R8600. Or any other radio I've had over the last 15 years.

Questions:
(1) Are there some obvious things (or not so much) I should check to ensure there are no issues with the radio-power supply connection?

(2) I have no idea why a 3 amp fuse would have blown... I have not seen the power supply ammeter ever go above 2.1A (when driving all three radios)--any ideas for what may have caused a blown fuse?

I had a very similar thing happen to my R8600 except I was present at the time and realised what happened.

Like you, I have my R8600 plugged into a 12V DC linear power supply - in my case a Yaesu FP-1030A. I also have a small break out box with multiple banana plug sockets in it for attaching accessories such as Bias-T's for Antenna pre-amps etc. What I did wrong was to unplug one of the barrel connectors out of the pre-amp to disable it. (I know - I should have pulled a banana plug) The socket was of poor quality (and design inside a diecast housing) and the plug created a short circuit during unplugging. Instead of blowing the fuse on that circuit, the inline fuse on the negative side of the DC power feed cord to the R8600 blew.

I suspect that the fuses Icom supplies are fast-blow or are actually below the rating marked on them. I was as surprised as you are. The only logical explanation was that because the pre-amp was still connected to the antenna, and that the co-axial braid is electrically connected through the antenna socket to the chassis on the R8600 - that the 'short' took a longer route through the coaxial cable through the R8600 power jack.

Some Icom receivers have the metal chassis connected to the negative rail of the 12V DC power supply - I know the R75 does - so I'm guessing the R8600 is wired the same.

Hence, any short circuit, lightning strike large or small, or voltage blip through an Antenna coaxial cable will be enough to take out one of those fuses on the R8600.

Just my 2c worth