Batboard

I have an Astro Spectra VHF High power radio configured for VRS operation using the VRS 750. It worked flawlessly until today. Now I'm getting the Fail 01/90 code with the unit connected to the Spectra on power up. Disconnect the VRS from the Spectra and the radio works fine after it detects the missing VRS. Any idea if there's an internal fuse on the VRS that might be causing the problem? Tried the VRS on another Astro Spectra with same results.

Thanks, Tom