Hi Jon,
The 2712 has been in dedicated power supply ripple QC duty. It is fed by a jig with 0.1 uF caps blocking the 14 V supply DC, so it only sees any RF on the SMPS supply rails. It is possible that one of the supplies being checked had a bad output filter and very high ripple, but I do not remember one.
Well, if that first mixer is burnt out I wonder if the CR256B or CA130 diodes have failed? I did a search through the archive for 2712 issues and did not find any other reports where the fault was found. I guess I'll have to pull the can and do some measuring.
Cheers!
Howie
