3.If A14J17 pin 1 does not appear to be correct, verify that the sweep ramp is reaching the Main/FM/VCO Sweep Switch as follows:
Change the oscilloscope’s amplitude scale to 1.25 V/d’iv and monitor the A14J15 pin 14. The waveform should be a 0 V to
Check that state of the Main/FM/VCO S weep Switches as indicated in Table
Note | Switches | U324A and U318C can change the polarity of A14U404B. This | ||||||||||||||||
| allows the Roller Oscillator to sweep backwards when the YTO is locked to | |||||||||||||||||
| a lower sideband of a Sampling Oscillator’s comb tooth. The YTO always | |||||||||||||||||
| sweeps forward (lower frequency to higher frequency), but the Roller Oscillator | |||||||||||||||||
| sometimes sweeps backwards (higher frequency to lower frequency). The FREQ | |||||||||||||||||
| DIAGNOSE menu will indicate a negative Main Roller frequency in this instance. | |||||||||||||||||
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| S o u r c e C C h o n 1 1 |
| C- S l o p e 1 | A u t o S c a l e C E n a b l e d | 1 |
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| Leve I | C | A d j u s t | 1 |
| - 2 . 5 0 0 v | O n E v e n t | 0000 | 1 |
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| P r o b e C | 1:l | 1 |
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| Coup1 i n g | Cdc | 1 Cl | Mnl | ||||||||
| X S e l e c t e d |
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| C u r s o r | 0 | +” |
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| C u r s o r | O - X |
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| 0 . 0 0 | v |
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| 0 . 0 0 | s |
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| SK1107 |
Figure
Table
Switch | Switch State | Switch Control Line | Control Line State |
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U318A | Open | 1 | High |
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U318C | Open | 9 | High |
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U318D | Open | 16 | High |
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U324A | Closed | 1 | High |
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U324B | Closed | 8 | High |
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U324C | Closed | 9 | High |
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Synthesizer Section 1