7B92: Difference between revisions
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The 7B92A uses one other custom IC, the [[155-0049-00|155-0049-xx]] sweep control circuit. The internal jumper for mainframe selection (7800/7900/7100 vs. slower) actually increases the minimum holdoff time on the slower mainframe selection by adding a 214pF capacitor (C307 for 7B92, C835 for 7B92A) to pin 8 of the sweep control IC [[155-0049-00|155-0049-xx]] in parallel to the existing capacitors. This increases the minimum pulse width of the holdoff signal on [[7000_Series_plug-in_interface|pin B4]] so that the sweep logic of slower mainframes can handle it properly. The effect of this jumper is only noticeable for sweep speeds of 20 μs/Div. and faster, since there the smallest shunt capacitance is used on pin 8, and the holdoff time is minimal. | The 7B92A uses one other custom IC, the [[155-0049-00|155-0049-xx]] sweep control circuit. The internal jumper for mainframe selection (7800/7900/7100 vs. slower) actually increases the minimum holdoff time on the slower mainframe selection by adding a 214pF capacitor (C307 for 7B92, C835 for 7B92A) to pin 8 of the sweep control IC [[155-0049-00|155-0049-xx]] in parallel to the existing capacitors. This increases the minimum pulse width of the holdoff signal on [[7000_Series_plug-in_interface|pin B4]] so that the sweep logic of slower mainframes can handle it properly. The effect of this jumper is only noticeable for sweep speeds of 20 μs/Div. and faster, since there the smallest shunt capacitance is used on pin 8, and the holdoff time is minimal. | ||
==Links== | |||
* [https://www.youtube.com/watch?v=uBeYAcD7Dds Zenwizard Studios - Tektronix 7B92A Calibration and Checkin] | |||
==Pictures== | ==Pictures== | ||