| Electronics > Repair |
| Tektronix TCP202 current probe repair - Schematic and suggestions needed |
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| KrudyZ:
The earlier versions of Tektronix current probes had a home brew looking switch assembly in it made from stamped metal pieces to let the amplifier know if the slider was closed. I'm not sure if they kept that "great" design in the TCP202, but that's where I would be looking. |
| Tantratron:
Here is a status on my attempt to calibrate-repair the TCP202. First I've completely de-constructed the probe head to observe any visible issue then re-constructed the probe, so far I did not see any problem (electrical or mechanical) which could explain the non-flatness response when sensing a 1KHz square signal (see attached some pictures of the de-construction). After that, I decided to connect a 100W incandescent lamp to the 230Vac-50Hz grid then probe with my P5210 and my TCP212, see pictures again where everything seems OK. So if we go back tony initial test, see both pictures where I'm using the tektronix 015-0672-50 calibrator 50 turns current loop, how can we obtain better flatness and rise time speed ! I've not opened yet the termination box of the TCP202 but do you think the circuit has some tuning or calibration to solve the issue ? |
| Tantratron:
P.S. regarding the tektronix 015-0672-50 calibrator 50 turns current loop, does anybody knows the schematics or circuit... does the calibrator really generates a super fast rise and fall 1KHz signal from the TDS front panel ? P.S.2. If someone owns the same tektronix calibrator and same TCP202 connected to a TDSxxx oscilloscope, could it be possible to make the same test which I did earlier to check the resultant waveform ? |
| MarkL:
It seems odd that you would get a perfect waveform when the jaws are not locked CLOSED. In your photo of the disassembled probe, are you showing all the parts? There should be a coil spring inside a metal sleeve which forces the upper sliding piece forward, and there should also be a tiny ball bearing. The ball bearing is important. It puts pressure on the wavy piece of spring metal to make sure the sliding transformer piece is seated firmly against the lower transformer. It's also the thing that "clicks" when you move the lever to the CLOSED position. Does your probe click? Also make sure the wavy spring metal is in the correct orientation. Screen shot from the TCP202 Instruction Manual attached: spring metal thing (10), coil spring and sleeve (2) and (3), ball bearing (12). I'm pointing these out explicitly in case someone else before you lost them. You may not know they're supposed to be there. |
| MarkL:
--- Quote from: Tantratron on October 12, 2020, 03:09:01 pm ---P.S. regarding the tektronix 015-0672-50 calibrator 50 turns current loop, does anybody knows the schematics or circuit... does the calibrator really generates a super fast rise and fall 1KHz signal from the TDS front panel ? ... --- End quote --- Looking at the compensator output circuit I wouldn't call it "super fast", but it should be faster than what you're showing on the TCP202. It doesn't seem likely it's the calibrator output but you can verify it's shape with a voltage probe. Schematic snippet from http://w140.com/tekwiki/wiki/TDS540 |
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