Electronics > Repair
Tektronix TCP202 current probe repair - Schematic and suggestions needed
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Pic:
Thanks' to these posts I was able to fix my broken TCP202 :)  I did a short when I removed the probe from an unisolated 400V wire.  :(

I want to share some hints for everyone who did the same mistake.
I exchanged the two SOIC-8 opamps. But it still did not work. Degauss, offset was working fine but the offset adjustment was quite sensitive. I figured out there was no voltage supplied to the HALL. The two 220R and two 1k resistors in series to the supply, next to the connector have gone high impedanze. I replaced them and now - everything is working again.

Many thanks' to you folks!
Tantratron:
Hello,

So far I've been using for most of my projects AC current probes P6021 and P6022 but lately I have new specific projects requiring DC-AC current probes.

What is the global return of experience using these TCP202, are they quality, calibrated stable with little failure if used correctly ?

Thank you, Albert
MarkL:

--- Quote from: Tantratron on April 07, 2020, 05:54:46 pm ---...
What is the global return of experience using these TCP202, are they quality, calibrated stable with little failure if used correctly ?

--- End quote ---
I think they are great probes.  I have two of them, one is about 20 years old now purchased new, and the other one used about 2 years ago.  I've had no performance issues with either of them.

The only failure I can recall is that the older one developed a crack in the bottom plastic surrounding the core about a year ago.  It hadn't quite reached the point of breaking off completely, and some plastic welder fixed it with no further cracking since then.  I've seen several photos of used probes with this bottom piece missing, so it makes me believe it's a common weak point in the design.

You might already know this, but being a powered probe, it does need a TekProbe II connection on your scope (or equivalent adapter), or an external power supply such as the Tek 1103.
Tantratron:
I've finally purchased one TCP202 probes from eBay in Austria, it came with a calibrate done by the vendor last week but for some reason, it does not work here in France.

When I connect the probe to my TDS540C, the corresponding channel will shift automatic to 50ohms input impedance, it will display A (Amperes) instead of V (Volts).

However when connected to a ballast source running at 250KHz, the signal is always zero plus it seems impossible to DC balance so no idea if the degauss works. The DC bias output stays always circa 20 mA flat.

I've then tried connect the probe to my spare tek 1103 power supply adapter then my tek 2465, same story with no output whereas it should display circa 1.5A peak sinewave generator at 250 KHz.

Do you know if the probe termination box circuits has some plug connector who could have moved or got loose during the shipment between Austria and France ?

Any suggestions or guidance, thank you
MarkL:
I'm assuming you mean you can't get it to zero with the knob on the compensation box.  Did you try the coarse balance adjustment on the underside of the probe body?

See page 3 here:

  http://w140.com/tek_tcp202_instruction.pdf

Also sounds like you're not getting any signal out of it.  Can you see any deflection with just a test DC current of 1A?
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