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.

Murlan Kaufman designed the THS700 series high voltage isolated front end.

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.

Firmware is updated using the 067-1436-00 Communication Pod with an adapter cable via an internal connector.

A THS710A and THS720A can be upgraded to a THS720P with the removal of a few resistors on the main board (see pictures for details). No adjustment/calibration is required after this modification.

NOTE: A THS710STD can be upgraded to a THS720STD, but due to main board differences, these models CANNOT be upgraded to a -A or -P model
Additionally, lower model scopes cannot be upgraded to a THS730A due to different input hybrid modules being used in the THS730A to provide the increased bandwidth.

Replacement Accessories

The DMM leads can be replaced with Mueller parts as used in the original lead kits 012-1482-00 for the standard set and ATLDX1 for the deluxe set as follows:

012-1482-00 DMM lead set contents (Mueller Electric part numbers):

  • BU-4061-M-39-0 - UL Listed, Threaded Test Probe to Banana, Silicone - Black
  • BU-4061-M-39-2 - UL Listed, Threaded Test Probe to Banana, Silicone - Red
  • BU-60TBO - Steel Alligator Clip with #8-32 Threaded Barrel (Two needed)
  • BU-62-0 - Insulator for BU-60 and BU-61 Series Clips - Black
  • BU-62-2 - Insulator for BU-60 and BU-61 Series Clips - Red
  • BU-00207-0 - Threaded Plunger Clip - Black
  • BU-00207-2 - Threaded Plunger Clip - Red

ATLDX1 DMM lead set contents (Mueller Electric part numbers):

  • BU-6161-M-39-0 - UL Listed, Test Lead Shrouded Banana Plugs Both ends Silicone - Black
  • BU-6161-M-39-2 - UL Listed, Test Lead Shrouded Banana Plugs Both ends Silicone - Red
  • BU-26101-0 - UL Listed, Test Probe Tip, Banana Plug Connection - Black
  • BU-26101-2 - UL Listed, Test Probe Tip, Banana Plug Connection - Red
  • BU-20431-0 - Right-angle Banana Jack, Hook Plunger - Black
  • BU-20431-2 - Right-angle Banana Jack, Hook Plunger - Red
  • BU-20433-0 - Flexible Rubber Coated Wire Grabber, Long - Black
  • BU-20433-2 - Flexible Rubber Coated Wire Grabber, Long - Red


The cigarette lighter adapter is a standard 1.8m (6 foot) long cigarette lighter plug to 5.5mm x 2.1mm (Type A) center positive DC 'coaxial power connector' plug with red led and 1 A fuse.


The console cable and adapter, part numbers 012-1364-00 and 103-0403-00 can be replicated using an 8p8c RJ45 to female DB9 rewireable adapter and a 2 M long 8-conductor telephone type cable (wired pin 1 to 1, 2 to 2, etc) or Cat-5 Ethernet cable with a ferrite clipped near one end, sourced from ebay or the like.

The pinout for the adapter is as follows:

RJ45 Wire Color Function DB9 (female)
1 Brown DCD- Data Carrier Detect 7 - RTS
2 Blue DSR- Data Set Ready 4 - DTR
3 Yellow DTR - Data Terminal Ready 6 - DSR
4 Green GND - Signal Ground 5 - GND
5 Red RXD - Receive Data 3 - TXD
6 Black TXD - Transmit Data 2 - RXD
7 Orange CTS - Clear To Send 7 - RTS
8 Grey RTS - Request To Send 1&8 - DCD/CTS


Included Accessories

  • P6113B - 10X, 100 MHz, CAT II, 300 VRMS Passive probes (THS710STD, THS720STD)
  • P6117 - 10X, 200 MHz, CAT II, 300 VRMS Passive probes (THS730A, THS720A, THS710A)
  • P5102 - 10X, 100 MHz, CAT II, 1000 VRMS Passive probes (THS720P)
  • 012-1482-00 - Meter lead set
  • THS7BAT - 4.8 V, 2.8 Ahr Ni-Cd Battery pack
  • AC Power Adapter
    • 119-4812-XX - North America
    • 119-4813-XX - Universal European
    • 119-4922-XX - United Kingdom
    • 119-4923-XX - Japan
  • 012-1364-00 - 2m RS-232 cable (8p8c RJ45 'console cable')
  • 103-0403-00 - 9-pin adapter (8p8c RJ45 to DB-9 adapter)
  • 016-1399-00 - Soft case
  • 070-9247-XX - User manual (THS710STD, THS720STD)
  • 070-9731-XX - User manual (THS730A, THS720P, THS720A, THS710A)
  • 070-9257-XX - Reference manual (THS710STD, THS720STD)
  • 070-9741-XX - Reference manual (THS730A, THS720P, THS720A, THS710A)

Optional Accessories

  • P5102 - 10X, 100MHz, CAT II, 1000 VRMS Passive probes (THS730A, THS720A, THS710A, THS710STD, THS720STD)
  • 012-1483-00 - Deluxe meter lead set (THS710STD, THS720STD)
  • ATLDX1 - Deluxe meter lead set (THS730A, THS720P, THS720A, THS710A)
  • THS7CHG - Battery charger
  • THS7BAT - Extra 4.8 V, 2.8 Ahr Ni-Cd Battery pack
  • 103-0090-00 - BNC to banana jack adapter to convert external trigger input to BNC (THS730A, THS720P, THS720A, THS710A)
  • 174-1734-00 - Cigarette lighter adapter
  • HC 411 - Thermal printer (006-7580-00 - Pack 5 paper rolls)
  • THS7HCA - Hard carrying case
  • A621 - BNC Current Probe, AC only, 2000 A max, 5Hz to 50 kHz
  • A622 - BNC Current Probe, AC or DC, 100 A max, DC to 100 kHz
  • A605 - DMM busbar-style current probe, AC only, 500A max, 48 Hz to 1 kHz, 1 mV/A
  • A610 - DMM busbar-style current probe, AC or DC, 500A max, DC to 440 Hz, 1 mV/A
  • P6129B - 1X-10X, 10 MHz/100 MHz Switchable passive probes
  • P6561AS - 10X, 100 MHz SMD probes
  • P6408 - Word Recogniser Trigger Probes - 16-bit word recogniser probe (trigger event recognition only)
  • S60DWAV - DocuWave DOS software (THS710STD, THS720STD)
  • WSTR31 - WaveStar software (THS730A, THS720P, THS720A, THS710A)
  • 070-9245-XX - Programmer manual (THS710STD, THS720STD)
  • 070-9751-XX - Programmer manual (THS730A, THS720P, THS720A, THS710A)
  • 070-9246-XX - Service manual (THS710STD, THS720STD)
  • 070-9752-XX - Service manual (THS730A, THS720P, THS720A, THS710A)

Software

Firmware

Pictures

THS720

THS720A

THS720P

Accessories