TDS784

Manuals – Specifications – Links – Pictures

The Tektronix TDS784 is a 1 GHz, 4 GS/s quad-channel digital storage scope.

There are four variants, all with the same specs but different hardware/software loads: TDS784A, B, C & D. Of these, the C and D models are the least problematic and most sought-after.

Specifications

Acquisition

• Sample rate: 1 channel @ 4 GS/s, 2 channels @ 2 GS/s, 3 or 4 channels @ 1 GS/s
• Analog bandwidth : 1 mV/div: 500 MHz, 2 mV/div: 600 MHz, 5 mV/div: 750 MHz, >= 10 mV/div: 1 GHz
• Resolution: 8-bit
• Record lengths : 50k samples per channel (500k with option 1M)
• Modes: sample, envelope, average, high-resolution, and peak-detect

Misc

• Display: color; Zoom
• Trigger modes Include: edge, logic, and pulse. Video trigger, with option 05 (NTSC, SECAM, PAL, HDTV, and FlexFormat)
• Storage: 1.44 Mbyte, 3.5 inch, DOS 3.3-or-later floppy disk. NVRAM storage for saving waveforms, hardcopies, and setups
• Units with option HD present (requires additional hardware) have a hard disk drive
• I/O: Full GPIB programmability
• Hardcopy output using GPIB, RS-232, or Centronics ports

Options

• 13 − Add RS-232C and Centronics hardcopy interfaces
• 1F − Floppy disc drive
• 1M − Extends standard acquisition length from 50,000 points per channel to 130,000 samples on three or four channels, 250,000 samples on two channels, and 500,000 samples on one channel
• 2F − Extended waveform math: FFT, integration and differentiation
• 2C − Communication Signal Analyzer; includes comm triggers and communication mask testing

Links

• Conversion of 500 MHz TDS744A to 1 GHz TDS784A
• Tek Forum threads:
  • Recovering the unit from a bricked state
  • Firmware updating
  • Backing up and restoring calibration data
• Simmconn Labs LCD replacement kits for CRT-based TDS O-scopes
• EEVBlog Forum thread on TDS options and how to enable them

Internals

For units with serial numbers prior to B04xxxx, the latest known firmware revision is 6.6e. For units with serial numbers B04xxxx and above, the last known version is 7.4e. Note that, due to differences in acquisition and CPU board hardware, release 7.4e will not work in the earlier revision units. Early revision units may have a CPU board P/N of 679-4172-00. The later revision is 679-4349-00.

It is also worth noting the TDS754 and TDS784 series are nearly identical, with the differences being in front-panel cosmetics and the presence (754) or absence (784) of a few capacitors on the acquisition board. The only other difference is the position of instrument ID jumpers, also on the acquisition board. In fact, it is entirely possible to convert a 754 to a 784 (see the 'Links' section).

Note that any kind of firmware updating of the 784 (and most other similar TDS scopes) requires very specific equipment, starting with an older computer (ISA slots required) running MS-DOS 5.x or later as well as Windows 98SE. To interface with the scope, you will need a National Instruments PC/GPIB-II ISA-based (8-bit) GPIB board or a National Instruments AT-GPIB (16-bit) board and appropriate drivers. The software required to do the update (Tektool or Tekfwtool) also runs under DOS (or a DOS box in Windows 98). Information on this tool can be found in the Links section in the thread describing firmware updates.

Actual calibration requires the above computer, the specific PC/GPIB-II card and drivers and an MS-DOS environment. You will also need an Analogic/Data Precision model 8200 DC voltage standard and a leveled sine-wave generator capable of going up to 1 GHz (if you're just doing a 754, you can get away with a 500 MHz top end). Naturally, Tek used the SG503 and SG504.

The reason for the specific model of voltage standard is because that's the model Tektronix wrote the calibration software for. During the calibration process, it issues automated commands specific to the Analogic.

Finally, for those with a dimming CRT, Simmconn Labs has developed a color LCD panel kit to replace said CRT in most of the TDS series which use them.