Astro Spectra Control Heads

[penstar]

I've got an astro spectra W9 that gives me the imfamous FAIL 01/90 upon power up. Changed out the vocoder board and still got the fail. Swapped vocoders with a good W9 (same band and power) and had no problems upon powerup on the good radio. I was able to enter the radios service menu by depressing the home key 5 times and it says that the control head is 21; actually cntlhd21.

Question. What's the difference between cntlhd21 and cntlhd24? I've seen them both on W9's. Could a cntlhd21 cause a fail 01/90 on radio with cntlhd24?