13.If the Transfer Oscillator drive signal is not present, check the XFER AMP BIAS at J303 pin 3. The voltage should measure +2 Vdc to +4 Vdc.
14.Check that the voltage at U424B pin 7 is nominally
15.Check that control signal XFEROSCSW is near 0 V (U424B pin 5). If XFEROSCSW is not near 0 V, check the Roller Interface Latch U401 and its address decoder U303. Refer to function block AG of Al4 Frequency Control Schematic (sheet 5 of 5) and function block B of Al4 Frequency Control Schematic (sheet 2 of 5).
16.If the signal amplitude at U109 pin 1 (refer to step 11) is within range and near 2 MHz in frequency, measure the signal with an oscilloscope at U109 pin 7. The voltage should nominally be 100
17.The waveform at U106 pin 7 should be a square wave with a lower limit between 0 V and to.5 V and an upper limit between +3 V and +5 V. Refer to function block AL of Al4 Frequency Control Schematic (sheet 5 of 5).
18.The signal at U105 pin 1 should have a similar waveform as U106 pin 7, but may be different in amplitude from the Offset Oscillator Dividers U103 and U104.
19.The Offset Oscillator Divider, function block AJ, is probably at fault if the signal at U105 pin 1 is not present and the Offset Roller is locked.
20.If the input signals to the Main Roller Phase Detector U105 (measured in steps 17 and
18)are in range, check for narrow (<O.l ps) pulses 0.5 ps apart on U105 pins 2 and 13.
21.Short U115B pin 5 to ground and check that U115B pin 7 is nominally
22.Short U115B pin 6 to ground and check that U115B pin 7 is nominally +9.1 Vdc.
23.If ERR 304 is displayed and the Main Oscillator PLL is locked, troubleshoot Roller MUX U305, MUX Amp U328, and MUX Gain Control Switch U326B. Refer to function block AG in Al4 Frequency Control Schematic (sheet 5 of 5).
24.If U305, U328, and U326B are working properly, suspect a malfunction of the A3 Interface Assembly or the W2 Control Cable.
25.Remove the jumpers.