Teardown - Pintek DP-25 Differentail Probe

[poida_pie]

so, Dave sez "get a differential probe!", it will save your life - maybe - but most likely will save your CRO and device under test.
I selected this modestly spec'ed one based on price and my needs.

I wanted good isolation of both differential probe inputs from my CRO, this is good for Cat 3 600V between either and ground.
I also wanted some decent amount of attenuation so as to view high voltage without blowing my CRO inputs.
The DP-25 has 200X, 50X and 20X attenuation settings, an over range light warning and it requires an external 9V 35mA supply.
When connected to your CRO and you select 1V/div and these attenuation settings will then be 200V/div, 50V/div and 20V/div
respectively.

These D.P. are made in Taiwan, seemingly OK prices for what you get. See
http://www.triosmartcal.com.au/oscilloscope-differential-probes/2303-pintek-dp-40lv-10mv-650v-differential-probe-40mhz.html
or
http://www.globalmediapro.com/dp/A01LT0/Pintek-DP-25-Differential-Probe-25MHz-1000V/ (whoever they are)
or ebay, where I bought mine.

You get a DP-25, two reasonably good quality banana style cables, big alligator clips, long narrow nose type clips, a short BNC-BNC cable and a 240VAC 9VDC plug pack supply.
I was surprised to see the power supply uses 9V +ve on the outside conductor, not inside as is usual.
I must confess to powering it with reversed polarity when I first used it and it survived. No smoke!
So that's good idiot proof design in the DC supply end....

The banana plug input is important to me as I planned to use the excellent quality Fluke test leads and clips, probes etc that come in their meter test lead kit in place of the crap you usually get supplied with cheap gear.
Pintek surprised me with the higher than expected quality of the supplied leads.

So what's it look like and what is inside?

It appears to generate it's own isolated power via a SMPS, to power the differential attenuator/amp circuit.
This uses a 2N3958 JFET (the TO-71 can package) and a LM6365 opamp.
Shielding is from a metalized coating applied to the inside of the ABS plastic casing.

The input attenuation and isolation are shown in the below photos. I can't comment on the design and build quality, maybe
others here can tell if it's OK or dodgy or whatnot.

I show a 800V p/p signal from a tiny HV supply from a photocopier light. This voltage is too high for the DP-25 and it shows "over range", but does not clip. It seems it will clip when the input exceeds approx 8 divisions (1 V/div on CRO) for all three attenuation settings.
So the maximum input before clipping seems to be +/- 800V. The manual clearly states +/- 500V as the maximum.

Finally I show the DP-25 compared with a normal old 10X probe, connected to the CRO's calibration square wave.
There is a fair bit of noise unfortunately, but I suppose that is to be expected. We are comparing noise from the JFET, opamp, unshielded probe leads etc., with a shielded  piece of wire (10X 100MHz probe)
Test conditions: Ch1 DP-25 output, 10mV/div, 20X attenuation, Ch2 10X probe, 20mv/div, 500mV square wave cal signal from CRO.

So, there you go. The $250 differential CRO probe from Pintek.

[HackedFridgeMagnet]

Anyone further info, about this brand of probes anyone?

This brand of probe is in my price range at the moment.

[EEVblog]

Anyone further info, about this brand of probes anyone?
This brand of probe is in my price range at the moment.

It's almost certainly going to do the job ok.
I prefer the ones with built in batteries like the Lecroy AP-031 I showed, but it's hard to beat the value of that one:
http://www.ebay.com.au/itm/New-Professional-Differential-probes-DC-25Mhz-ADP25-Max-Voltage-1300V-1000V-RMS-/380411972965?pt=AU_B_I_Electrical_Test_Equipment&hash=item5892520d65
(I think) the OEM of the Lecroy one are reasonably priced:
http://www.triotest.com.au/shop/en/home/1531-sapphire-instruments-si-9001-differential-probe-25mhz.html

[LaurentR]

Reviving this thread on differential probes, hoping to get some owners to chime in, I found that there are basically 2 big OEMs of rthe less expensive (hesitating to say cheap) 25MHz differential probes:

The Pintek DP-25 from this thread (AC powered only) is found under the Rigol, Siglent and Instek names in the $300 range (although an EBay seller seems to sell a lot of the Pintek-branded version at $212 right now http://www.ebay.com/itm/New-Pro-Differential-probes-DC-25Mhz-Max-Voltage-1300V-Tektronix-OEM-Taiwan-CAT3-/300710178863?pt=LH_DefaultDomain_0&hash=item4603b9302f).

Note that Pintek also has low-voltage versions of that probe that may be better noise-wise (but they are far less common on the interweb).

The Sapphire/Testec that Dave shows (battery and AC) is found under LeCroy, Agilent, BK Precision, Cal Test, ProbeMaster and a bunch of other ones. These start at $300 also (Agilent and LeCroy are more expensive  ).

Any extra feedback on these 2? I looked at used brand names on EBay too, but things like the Tek P5200 is about the same price used. The HP 1141A can be found in that range too and could be a good deal, although it's a bit more involved (and better).

[EvanShultz]

How to safely get the PCB out of the chassis? It's held on by the knob, and I'm afraid to use too much force and cause damage.

[Arlo1]

Hi guys I know I am reviving an year old thread.   But its important.   I have a pintek 25mhz differential probe and a rigol ds1052 hacked to 100mhz.  I would like to get a second diff probe soon.  I am ok with the pintek but I would like a bit more bandwidth.  I am working with power electronics and I need to make sure I can see as much as I can.  I think 50mhz is enough and 100mhz would be more then enough.   

Is there any places to point me in the right direction?  I am on a budget but I will spend the money if I can justify it.

I am also looking to upgrade the scope soon.  Looking at the 70mhz 4ch rigol but open to others as I just started shopping.
Also ~1000v DC is enough
Any info or updates would be awesome.
-Arlin

[saturation]

Pintek has various models in that line with many kV and/or MHz ratings, choose the combo you need.

http://www.pintek.com.tw/

See under differential probes.

[alank2]

I got a new PINTEK DP-25 today and have played around with it.  The manual says x20=15 MHz, x50/x200=25 MHz so I thought I'd hook it up to my SDG2082X to see some signals on it.  What I noticed is that the switch between x20/x50/x200 modes is good at lower bandwidths, but at 20 MHz, it isn't pronounced. 

1 MHz - 10 vpp - 50ohm mode - bnc cable with pass through 50 ohm terminator to a bnc to banana adapter.

1 MHz, 20x = 10.56V, 50x = 10.60V, 200x = 11.52V
10 MHz, 20x = 9.36V, 50x = 11.10V, 200x = 19.52V
20 MHz, 20x = 6.48V, 50x = 11.90V, 200x = 36.80V

I used a BNC to alligators and didn't do the 50 ohm termination with hiz mode and the results were similar.  At lower bandwidths they are all very similar, but as the bandwidth goes up, the 200x mode seems to multiply.  Since the 20X mode is only rated to 15 Mhz, it is probably fine.

Any thoughts on why this is?

[TheSteve]

What voltage/power is your 50 ohm pass-through rated for and is it still 50 ohms?

[alank2]

You make a good point, it is a Pomona 4119 - says 50 ohms 2 W on the side of it.

[alank2]

Same test, HiZ, no terminator:

1 MHz, 20x = 10.64 V , 50x = 10.7 V, 200x = 11.52 V
10 MHz, 20x = 9.44 V, 50x = 11.3 V, 200x = 19.68 V
20 MHz, 20x = 6.8 V, 50x = 12.6 V, 200x = 39.2 V

[tautech]

Alan, I checked a DP-25 I have in stock and there might be some confusion when reading the manual.
There's mention of 50 load but with a DSO I'm using 50 input termination just stuffs things up. 
Now it does say in Features for a DP-25:
The DP-25 is designed to operate with 1M impedance oscilloscopes.
When combine (used) with 50 load the attenuation will be 2 times. (more)
http://www.pintek.com.tw/files/pintek/DP-MANUAL.pdf

Pintek supply a 50 1 meter BNC cable with the DP-25 YET plainly printed next to output BNC is:
< + 8V into 1M .

Now I've only checked it with my trusty old SDG1010 with 1 Mhz and 10 MHz sinewave @10V p-p using the DSO's OSD measurements which of course adds a further element of error. I honestly don't know when I'd use a differential probe at these frequencies, in all that I can think of would likely be below 200 KHz.


SDS2304X 1M input, SDG1010

Frequency   DP-25 Attenuation     DSO input attenuation       DSO V/div        DSO OSD measurement. (V p-p) 1 MHz                        x20                                10x                        2                                  10.48                                   x50                                20x                        2                                    8.56                                   x200                             100x                       2                                   10.88 10 MHz                      x20                                 10x                        2                                   11.2                                   x50                                 20x                        2                                   10.64                                   x200                               50x                       2.5                                 10.1

All settings were made to get a ~70+% amplitude waveform on the display in order for the OSD measurements to be somewhat accurate. Little experimentation with 20 MHz BW limit was used too and this affected measurements in some small way both + and -.
Both instruments Self cal'ed before test.

I like you am a little surprised by the errors and it could well be worthy of tests with some different waveforms............

[alank2]

I agree tautech, when reading the manual befoe it arrived I saw its mention of 50 ohm, but on it, it clearly states "output <= +/- 8V into 1 M ohm".

The biggest one with an issue is 200X, but perhaps no one uses 200X at higher frequencies.  Still, the way it performs doesn't agree with the specifications unless I am misunderstanding something or did the test wrong.  The way I see it, 50X is the best overall range, and 20X is fine up to 17 MHz or so which is a letter better than spec.  200X is fine at lower frequencies.

[alank2]

Power requirements are that it says "9V 200mA max", but they supplied it with a 9V 300mA wall wart that puts out 11.1V when it draws 100mA from it.  It has a larger startup current (560mA) briefly, then settles to 100mA.  If you limit the startup current to 250mA, it won't get past the startup, at a current limit of 400mA it would work though.  At 6.8V or above the waveform is fine, but when I go to 6.7V, it begins to move downward on the scope.  Their website site says "Regulation circuit is working properly at input 5V ~ 14V. When power lower than 5V, the output circuit will shut down automatically to make sure output is OK."!!

[Coyote]

I have one question. Looking on web they sell DP25 1400Vpp, 1000V CAT III. The accompanying pictures show a device with prints on: 600V CAT III, 1000Vpp, 350VAC rms.

This is the link of Pintek website:
http://www.pintek.com.tw/product_detail/landersound/index.php?Product_Site_Classify_SN=17072&Product_SN=19265&Company_SN=6002

They are contradicting themselves. Anybody knows what are the real specifications? It is 1400Vpp or 1000Vpp? Because with 1400Vpp the rms voltage would be 1400/(2*1.41) = 500VAC RMS, which is suitable for 400VAC network. 1000Vpp gives only 350VAC RMS.

[alank2]

More specs from their site:

http://www.pintek.com.tw/files/pintek/DP-25-spec.pdf

http://www.pintek.com.tw/files/pintek/DP-MANUAL.pdf

I think one says 1300 and one says 1400!

[Electro Detective]

Thread re-boot   

Any members clued if this DP-25 probe can be powered from a 9 volt battery with adapter cable/lead for a short time? 

or it just won't start up/kick over ?

I would like the option to avoid any mains related connection/wall wart etc


I suppose a small 6 volt brick or SLA 'should' do it,

12 volt SLA or car battery probably won't

Is the DC terminal a generic stock barrel type or...  ?

 

[tautech]

Thread re-boot   

Any members clued if this DP-25 probe can be powered from a 9 volt battery with adapter cable/lead for a short time? 

or it just won't start up/kick over ?

I would like the option to avoid any mains related connection/wall wart etc


I suppose a small 6 volt brick or SLA 'should' do it,

12 volt SLA or car battery probably won't

Is the DC terminal a generic stock barrel type or...  ?

The factory supplied wallwarts are 9V DC 300mA rated, linear type. No load open circuit:12.3V  5mm barrel connector, center negative.

[OldDogSleeping]

I power mine using a USB to 9v step up convertor cable. It seems happy plugged into the usb port on the front of my DS1054Z.

[tautech]

Defpom has a quick look at a Pintek 8 KV HV scope probe and the DP-25 differential probe.

[HarryMack]

This must be an older model but it still says Pintek DP-25 and has an internal 9V battery, I planned on running the one I just received with USB power bank with 5V to 9V adapter cable after opening up and reversing leads to center negative.