Teardown and repair of Tektronix TDP1000 differential 1 GHz probe

Active probe such as Tektronix TDP1000 rated for providing 1 GHz bandwidth and designed to operate in single-ended or differential mode. It have good high-speed electrical and robust mechanical connection for probing. It is current generation probe designed for Tektronix oscilloscopes TekVPI™ probe interface or older TekProbe™ BNC ports.

Feature set of this probe:

  • 1 GHz analog bandwidth
  • less than 1pF differential input capacitance
  • 1 MΩ differential input resistance
  • ±42 V (DC+pk AC) differential input voltage and input offset range
  • Attenuation x5 or x50
  • Noise level <2mVRMS at x5 or <1mVRMS at x50
  • Rise time <350 ps (for TDP1000/P6251)
  • >18 dB CMRR at 250 MHz
  • Selectable 100 Hz, 10 kHz, 1 MHz or full BW
  • DC reject at 0.4 Hz (x5) or 4 Hz (x50)

I’ve bought this probe as broken/for parts. MSRP for the new Tek TDP1000 is around $4600 USD.

Diagnostics

Probe had no physical damage from outside, did not have any accessory bundled with sale. After connecting to Tektronix DPO7104 scope probe was correctly recognized and detected.

AC square-wave from scope’s calibration output showed up on scope just fine.

However further testing revealed that probe DC output level clipped high at +2.28 V no matter what settings used.

Both positive and negative inputs were able to pass signals, so it must be something damaged within active amplifier or power supply rail.

Also probe end with all high-speed die-bonded electronics getting really hot after few minutes of operation. It is normal for active probes to stay warm, but not burning finger hot.

Teardown

Probe has all auxilary electronics in connector head, that plugs into TekVPI oscilloscope port. There are two 4-layer PCBAs, mounted to each other and heatsink shields.
Typical to Tektronix probes, there is little ATMEL ATmega32 8-bit microcontroller to select various probe functions, provide digital identification for scope, store serial number, etc.

Onboard hardware handle programmable DC offset vernier function. It is implemented around BB DAC7612U which is dual-channel 12-bit fast voltage DAC. There are two dual ultra-low bias current high gain TI LMC6022 amplifiers

Second board is essentially power supply to convert input +12V Bulk from scope into auxilary rails used by probe electronics. Three is TPS73001DBV LDO for +5V rail, LM317MG in DPAK, TPS732 for negative rail and Linear LT1616 switch-mode supply for +/-15V.

TBC

Author: Illya Tsemenko
Published: April 12, 2020, 10:24 p.m.
Modified: April 12, 2020, 11:03 p.m.

References

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