Sal,
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I have a 5335A that has been sitting on the shelf that has been awaiting attention for some time.? It was once fully functional but developed a couple of error messages unexpectedly.? And, as I indicated, I still have to open it up and look around to see what is happening.
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When first powered up there is a fail message 4.6 (MRC COUNTING PROBLEM IN REG-E OR T).? If any button is pressed the fail messages changes to 5.1 (START INTERPOLATOR PROBLEM) and the display and other indicators begin to flash erratically.
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Perusing the schematics I get the impression that there is possibly a clocking problem around the Multiple Register Counter (MRC) U6 that also fees the Interpolator counters via the start-stop control circuitry.? All of these items use the 10 MHz clocking.
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If you have the manual (mine is P/N 05335-90021 3rd edition March 1983) I recommend starting at the troubleshooting flowchart on page 8-57.? It will lead you to the proper following pages describing the troubleshooting techniques plus voltages & waveforms.? A good overview of the whole unit is shown in the block diagrams on pages 8-97 (for options 010, 020 & 030) or page 8-99 (if your unit includes option 040).
The circuitry that I referenced earlier is located in the upper right corner of these block diagrams in the ¡°A4 MAIN LOGIC¡± block.
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Sorry that I cannot assist any further since I have not had the time to really investigate the failures this unit is showing but I hope that what I have written will serve as some rudimentary guidance should you have to dig deeper into locating your problem.
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Regards,
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Greg
