[Premium-Rx] Harris RF-590 A12 800khz missing

[Gilbert Harris]

You likely received an A12-2 FAULT indicating bad BITE test located on the 800khz reference. This originates from U5 4mhz reference at pin 5 which is then divided by 5 at U6 with output at pin 5 (800 khz.)  U5 also provides 4mhz which is divided by U4 for the 1mhz reference output. This is tested PRIOR to the 800khz during FAULT testing so  the problem is after U5.  Go to U6 and measure its supply voltage, then if ok press on near by circuit board for cold solder joint, put oscilloscope on pin 1 ( input 4mhz) and pin 11(output 800mhz).  I'll bet you have done already. I may have a couple A12/A21 somewhere but can't access for 6 weeks.