THS720

Manuals – Specifications – Links – Pictures

The Tektronix THS720 is a portable 100 MHz, 500 MS/s (each channel) dual-channel digital oscilloscope with isolated inputs. There were two variants, the THS720 STD and the THS720A. The primary difference is that the THS720A will trigger from the DMM input.

The THS720P includes features for electrical/power electronics measurements.

THS700 series high voltage isolated front end design was done by Murlan Kaufman.

Key Specifications

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Operation

Due to the isolated inputs, the probe ground must be connected even when compensating the probes with the "PROBE COMP" output. It can be used with any BNC probe but the scale factor pin found on many Tektronix probes is not used. The vertical menu has a scale factor entry (1×, 10×, 100×, 1000×) which can also be used for direct BNC inputs.

Recommended probes are the P5102 and the P6113B, both are 10× probes with protected grounds for isolated measurements. The P5102 has the best isolation, allowing 600 V between reference ground and earth ground.

Internals

Primary microprocessor is the Motorola/Freescale MC68331CFC16. 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 DMM is a 3¾-digit Maxim MAX134CQH.

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 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 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 since one side of channel 2 goes through 2 vias not found on channel 1.

Pictures

THS720

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  THS720 STD displaying probe compensation waveform

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  THS720 STD top of main PCB

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  THS720 STD back of main PCB

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  THS720 STD attenuator with cover removed

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  THS720 STD operation without case

THS720A

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THS720P

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  THS720P Top of Main PCB

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  THS720P Bottom of Main PCB