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THS720: Difference between revisions
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There were two variants, the THS720 STD and the THS720A. | There were two variants, the THS720 STD and the THS720A. | ||
The primary difference is that the THS720A will trigger from the DMM input. | The primary difference is that the THS720A will trigger from the DMM input. | ||
{{MissingSpecs}} | |||
==Operation== | ==Operation== | ||
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An Intel E28F008SA120 Flash Memory chip is used for setup, cal and waveform storage. | An Intel E28F008SA120 Flash Memory chip is used for setup, cal and waveform storage. | ||
The switching power supply is run by a TL1451A, a TI two channel boost/buck controller. | The switching power supply is run by a TL1451A, a TI two channel boost/buck controller. | ||
The DMM is a | The DMM is a 3¾-digit Maxim MAX134CQH. | ||
The analog scope section starts with an attenuator hybrid driven by | The analog scope section starts with an attenuator hybrid driven by four channels of | ||
HP (now Avago) optoisolators and NEC relays. The hybrid contains the AC coupling | HP (now Avago) optoisolators and NEC relays. The hybrid contains the AC coupling | ||
capacitor and many laser trimmed resistors along with a custom Tek [[165-2545-00]] BGA. | capacitor and many laser trimmed resistors along with a custom Tek [[165-2545-00]] BGA. | ||
The signal then passes through a single-ended to differential transformer and | The signal then passes through a single-ended to differential transformer and | ||
goes to a custom labeled Maxim | goes to a custom labeled Maxim two-channel high speed A/D converter [[234-1503-20]]. | ||
Note that the differential signal layout for channel 2 is not as good as channel 1 | Note that the differential signal layout for channel 2 is not as good as channel 1 | ||
since one side of channel 2 goes through 2 vias not found on channel 1. | since one side of channel 2 goes through 2 vias not found on channel 1. | ||
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When confronted by scope calibration failures that say "Cal error, DC balance" | When confronted by scope calibration failures that say "Cal error, DC balance" | ||
and there are | and there are persistent DC offsets that increase with the attenuator settings | ||
try replacing U45 and U46. They are HP CNR201A analog optoisolators, now made | try replacing U45 and U46. They are HP CNR201A analog optoisolators, now made | ||
by Avago as the HCNR201-300E. They send a low pass filtered version of the | by Avago as the HCNR201-300E. They send a low pass filtered version of the | ||
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ths720std-attenuator.JPG|THS720 std attenuator with cover removed | ths720std-attenuator.JPG|THS720 std attenuator with cover removed | ||
ths720std-scopeanalog.JPG|THS720 std analog scope section | ths720std-scopeanalog.JPG|THS720 std analog scope section | ||
Tek | ths720std-runningboard.jpg|THS720 std operation without case | ||
Tek ths720a 1.jpg|THS720A | |||
Tek ths720a 2.jpg|THS720A | |||
Tek ths720a 3.jpg|THS720A | |||
Tek ths720a 4.jpg|THS720A | |||
Tek ths720a 5.jpg|THS720A | |||
Tek ths720a 6.jpg|THS720A | |||
Tek ths720a 7.jpg|THS720A | |||
Tek ths720a 8.jpg|THS720A | |||
</gallery> | </gallery> | ||
[[Category:THS series scopes]] | [[Category:THS series scopes]] | ||