THS720: Difference between revisions

Revision as of 05:36, 15 March 2023

Tektronix THS720

150 MHz 4-ch digital scope

Produced from (?) to (?)

Manuals

THS710, 720

THS710, 720, 730

User 070-9731-05
Other versions: -03 / -01
Reference 070-9741-01
Other versions: -00

THS710A, 720A, 720P, 730A

User 070-9731-05
Service 070-9752-02
Other versions: -01 / -00
Programmer 070-9751-01
THS720A Component-level Information Package

Other

Tektronix THS700 Series Product Brochure (2006)

(All manuals in PDF format unless noted otherwise)

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.

Key Specifications

please add

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 600V 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 Std displaying probe compensation waveform
THS720 std top of main PCB
THS720 std main board MCU and DMM
THS720 std main board BNC inputs and power supply
THS720 std back of main PCB
THS720 std attenuator with cover removed
THS720 std analog scope section
THS720 std operation without case
THS720A
THS720A
THS720A
THS720A
THS720A
THS720A
THS720A
THS720A

@@ Line 1: / Line 1: @@
-[[Image:Ths720std-comp.jpg|thumb|400px|right|Tektronix THS720 Std probe compensation]]
+{{Oscilloscope Sidebar
+|manufacturer=Tektronix
+|series=THS series scopes
+|model=THS720
+|summary=150 MHz 4-ch digital scope
+|image=Ths720std-comp.jpg
+|caption=Tektronix THS720
+|introduced=(?)
+|discontinued=(?)
+|manuals=
+'''THS710, 720'''
+* [[Media:070-9247-02.pdf|User 070-9247-02]]
+* [[Media:070-9246-03.pdf|Service 070-9246-03]]
+* [[Media:070-9245-00.pdf|Programmer 070-9245-00]]
+'''THS710, 720, 730'''
+* [[Media:070-9731-05.pdf|User 070-9731-05]]<br/><small>  Other versions: [[Media:070-9731-03.pdf|-03]] / [[Media:070-9752-01.pdf|-01]]</small>
+* [[Media:070-9741-01.pdf|Reference 070-9741-01]]<br/><small>  Other versions: [[Media:070-9741-00.pdf|-00]]</small>
+'''THS710A, 720A, 720P, 730A'''
+* [[Media:070-9731-05.pdf|User 070-9731-05]]
+* [[Media:070-9752-02.pdf|Service 070-9752-02]]<br/><small>  Other versions: [[Media:070-9752-01.pdf|-01]] / [[Media:070-9752-00.pdf|-00]]</small>
+* [[Media:070-9751-01.pdf|Programmer 070-9751-01]]
+* [[Media:070-9750-02.pdf|THS720A Component-level Information Package]]
+'''Other'''
+* [[Media:061-4241-00.pdf|THS720/THS730 Release Notes 061-4241-00]]
+* [[Media:THS7XXAPDiag.pdf|THS700 Schematics]]
+* [[Media:3MW-10566-6.pdf|Tektronix THS700 Series Product Brochure (2006)]]
+}}
 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.
@@ Line 33: / Line 62: @@
 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.
-==Repair Issues==
-The service manual shows how to remove the calibration protection jumper.
-The DMM calibration step requires a good calibrator capable of doing 850 V<sub>DC</sub>
-and 600 V<sub>AC</sub> at 500 Hz.  Scope calibration is much simpler requiring only a
-square wave pulser and a DC voltage source.  Note that after a cal fail, there
-is an error log in a nearby menu indexed by power on count.
-When confronted by scope calibration failures that say "Cal error, DC balance"
-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
-by Avago as the HCNR201-300E.  They send a low pass filtered version of the
-input signal across the isolation barrier to give the DC levels that can not
-cross the high frequency transformer isolation barrier.
-The battery pack is, of course, custom.  It appears to be 4 C cell NiCd pack
-with the positive terminal moved to a ring around the bottom (most negative) cell.
-If you are not concerned with interchanging packs or using the separate charger, the
-cells can simply be soldered into the lower housing.
-See [[THS700]] for the manuals.
 ==Pictures==