I too have seen a failed power resistor. ?Other failed item maybe be a leaky diode that then shuts down the power supply. ?If the -40v supply is other than 0, -40v suspect a leaky diode, or shorted or leaky cap on the affected supply. ?
You will also get a similar symptom if you have an ext 10 MHz ref and it drops out, or you lose the internal 10MHz, or the 100MHz loop is down.
Don Bitters
