Allen & Heath RPS11 random fuse blow issue
I have an RPS11 supply on the bench here and the customer says that it blows the mains fuse once out of 4 to 5 power on cycles. On the bench, I've not been able to get the fuse to blow at all. Currently, the customer is using another backup power supply for the same mixing console and hasn't had a problem since.
The unit specs a 5 amp time lag fuse but the customer used a fast-blo 5 amp. I've been using a 5 amp slo-blo for about 20 start-ups with no failures. Voltages are on-spec +/-16vdc and +48vdc.
The blown fuse the customer used was blackened (blew hard) on the inside of it. So first, I brought the unit up on the variac, successfully, and then had several successful cold starts. I inspected the casings of the power switch, AC inlet/fuse box and power transformer for compromised insulation which may cause a temporary arch shorting to ground but did not find any evidence of such.
Anyone come across anything like this before?