EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: McBryce on September 11, 2015, 10:19:19 am
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Hi all,
this week I got myself a Pintek DP-100 Differential Probe from a liquidation sale. This is a 6.5KV 100MHz diff probe. Unfortunately it was only the unit, no probes or PSU included as the liquidation company in their infinite wisdom went and sold the probes as part of a "Test-lead lot" and the PSU probably went with some other non-related bundle :( Not a major problem for me, but it does mean that the teardown is only the main unit. So here goes...
First up, the outer case. It's big - 23cm (not including the BNC connector at the end) by 8.5cm (widest point). On the back there's the expected UL/IEC/EN certifications and a made in Taiwan sticker. On the front you get an on/off/attenuation selector, which feels really solid and has very defined "clunky" positions. No mistaking that you've changed the selection. Attenuation can be set to 100x, 200x, 500x or 1000x. You also get two LEDs for power and low battery. The case passes Dave's bend/squeak test. The screws have proper enbedded metal holes, not self-threaders.
Inside it's obvious that some very similar design techniques to the DP-25 were used. The upright PCB for the banana sockets are similar, however it's split in two here, the DP-25 just had one for both sockets. There's also no metal coating on the case surface as seen on the 25. The schematic is completely different, with quite a bit more on the PCB. The battery compartment has some cheap sponge inluded to stop the battery from rattling. It's cheap, but it works well.
The PCB looks well planned and designed, with the required cut-outs at the high-voltage end. The soldering quality is also top-notch. All ICs are soldered except for the 8pin DIP IC at the 9V input stage marked CPA - P136AP4 (have to check what that is). The critical capacitors are from OS-CON (Panasonic).
Not much more to say about it at the moment. I won't get to test it until tomorrow. Any questions, just ask. Enjoy the pictures...
McBryce.
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More pics...
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Thanks for sharing, and excellent close up shots too ! :-+
Looks like its still using thru hole components.
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Yup, other than the input coupling capacitors it's all thru-hole, no parts on the bottom of the PCB.
McBryce.
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thanks for sharing the clear and nicely angled shoot pictures... you can easily build the probe and specify the performance. if its not acceptable, try adding some resistance on the probe tip and see how its improves... ymmv...
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Very nice teardown and pictures, thank you.
It is a surprise that in these days they would not make all parts SMD.
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The guy I bought it from told me there were one or two more of these when they cleared the lab. He says he'll get back to me when he's found them. If anyone (probably best just within Europe due to postal costs) is interested in one, they should send me a PM.
McBryce.
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It is a surprise that in these days they would not make all parts SMD.
i suspect the original design came not from these days and they dont have enough time or resources for a new RnD...
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That's an interesting view of the underside of the input section - I've never seen smd caps bridged over slots that extensively before, I wonder what its vibration / shock tolerance would be. Actually from the vias on the underside it look as if it might have been designed to accommodate through hole ones as an alternative. Better HF performance with smd I wonder?
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First time I'd seen that too, which is why I made sure to get some good pictures of it. Yes, there are holes for thru-pin on each finger too. The capacitors have serious blobs of solder on their terminals as if they were hand soldered, so they should withstand quite a bit of vibration and general bashing.
McBryce.
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I received my Pintek DP-100 this week from McBryce - thank you so much for a very smooth transaction.
First thing to notice is really the sizes, because it is larger than one would expect from the pictures.
Built quality is really nice and the turn switch moves very smooth.
Just hooked it up to a 400 to 500 Volt inductive switching signal and it works perfectly alright on my MSO7054B Agilent scope.
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Curious, what is the common mode rejection of this differential probe at 100 Mhz?
Bernice
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Hmm that might be a rookie question, but how come this probe is 100 MHz with just ordinary banana jacks? 6500V, 100 MHz, that is a massive slew rate.
I always thought that even at these frequencies even stupid crocodile ground clip of a passive probe causes trouble and you might get lucky with the spring attachment. More likely one would rather use low-Z0 terminated to 50 Ohm or, as a matter of last resort, a proper active probe.
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Being a Tek P6046 user for decades and knowing what is absolutely required to achieve reasonable Common Mode Rejection at even one Mhz, how does this diff probe achieve any reasonable CMR using banana jacks, let alone being rated at 100 Mhz?
Is there a published chart-curve for CMR and does this diff probe meet the published spec?
Bernice
Hmm that might be a rookie question, but how come this probe is 100 MHz with just ordinary banana jacks? 6500V, 100 MHz, that is a massive slew rate.
I always thought that even at these frequencies even stupid crocodile ground clip of a passive probe causes trouble and you might get lucky with the spring attachment. More likely one would rather use low-Z0 terminated to 50 Ohm or, as a matter of last resort, a proper active probe.
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6500V, 100 MHz, that is a massive slew rate.
the trick is in the 1/1000X attenuator...
...a proper active probe.
this thread is about differential probe, not active probe...
Being a Tek P6046 user for decades and knowing what is absolutely required to achieve reasonable Common Mode Rejection at even one Mhz
what is required? is the user has to make sure both nodes' impedance that to be measured have to be the same? both probe's cable have to be as close as they can get? matched length and occasionally being calibrated? or the user has to know what to do and what to not do, to make proper measurement maximizing cmrr not relying 100% on the measurement device?
how does this diff probe achieve any reasonable CMR using banana jacks
using some test setup to calibrate and specification. but i believe at 100MHz, the CMRR is abysimal, regardless of brand name in low to middle class price tag..
I always thought that even at these frequencies even stupid crocodile ground clip of a passive probe causes trouble and you might get lucky with the spring attachment.
let alone being rated at 100 Mhz?
the keysight did claim so using banana jack, so can the china not so far behind!
http://www.testequity.com/products/1727/ (http://www.testequity.com/products/1727/)
maybe we can knock there door to ask how they did it. resistive cable maybe? or in the compensation network? maybe...
Is there a published chart-curve for CMR and does this diff probe meet the published spec?
did they even make it published? i did try to find it sometime ago to no avail, so the spec can be anything...
i for one, also looking forward to somebody to specify this china kind of device to see how they perform CMRR-wise...
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Thanks for the peek inside looks nice.
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Looks like input stage is just huge attenuator -> bjt differential amplifier -> op-amps to amplify it back :)