Tektronix TCP0030A Current Probe

[Evan.Cornell]

I took a risk on an un-tested Tektronix TCP0030A current probe. Unfortunately, when I plug it into my MDO3014, the "Jaw Open" led just blinks red. I don't find any reference to this error mode in the user manual. Does anyone have any idea what this means, and if it's fixable?

Thanks!

[Evan.Cornell]

Yes, it is closed. I have a known good model right next to it.

I found disassembly instructions in TCP0030 manual.. is the micro switch in the jaw unit itself?

[Evan.Cornell]

So I unplugged and re-plugged, and the probe seemed to come up more normally (5A range on, Degauss light flashing, Jaw open light off). But degauss button doesn't respond, and the scope doesn't see the probe. I unplugged and re-plugged again, and it's back to Jaw Open blinking. That sort of seems like a logic fault of some sort...

[Evan.Cornell]

I rebooted the scope with both TCP0030As plugged in. The known good unit has the 5A and Degauss LEDs light up dimly, until after the scope boot sequence completes and the probe is recognized. The bad probe has no LED illumination at all. That to me points a little bit to a power supply issue in the current probe.

I just checked the TekVPI interface. The +5V pad doesn't come up immediately on scope boot, but the BULK (~12V) rail does. So I am guessing that there is a 12V-to-something DC-DC in the probe that isn't working properly.

[TiN]

Ah, it was you who got that one out of me

I'd start with disassembly to find out if anything obvious broken like open joint or loose wire.

[HighVoltage]

I have repaired many Agilent / Keysight current probes and they all have a micro switch inside.
Although, I had one broken micro switch, most times it was a metal lever that did not reach the micro switch all the way and with a little adjustment of the switch position or the metal lever, it worked again.

This problem should be easily fixable.
   

[MarkL]

If the TCP0030A is anything like Tek's older models (TCP202A, A6302, and others), there's a set of sliding contacts in the probe head that detects when the jaw is locked.  And if you end up taking it apart, be careful not to lose the tiny metal ball sitting in a recess which is the thing that "clicks" when the jaw is locked (at least on the older models).

But it sounds like you have issues in the probe box and not in the probe head.  That's where I would start.  And if you already have a working one, you can compare voltages at various points inside the two boxes.

[Evan.Cornell]

Hmm. So i opened up the probe calibration box today, got the unit disassembled, unplugged the connector for the probe jaw and one of the wires came loose from the crimp. Soldered back into the crimp, re-assembled, still no luck.

So, I disassembled again, and one of the pogo pin connectors on the TekVPI interface (3pins) popped right off the board. Not enough solder-paste, not a good reflow perhaps? J15 on the board. One of these three pins is +12V from the scope, so I suppose that could be the culprit.. Does anyone happen to know if that fits with the failure mode (blinking jaw open LED) ?

[Evan.Cornell]

And reflowing the 3-pin Pogo pin from the TekVPI interface seems to have brought this probe back to life!