Rigol's New DHO800 Oscilloscope unbox & teardown

[norbert.kiszka]

...
Mine is from this link and is working fine.
It came with Chinese power cord, which can be replaced and with Chinese menu, which can be switched to English or any other supported language.
I bought it for about 380 euro, including the shipping, from the EU warehouse, now it is under 340 euro with a coupon...

Same with mine, purchased almost a year ago -- it's working without any problems. Interesting fact: The current offer lists the power brick not included, maybe that's the reason for the lower price. Maybe these are really manufacturer rejects that get shipped incomplete due to a QC failure? Just wondering...

And maybe that's the reason of problems with such scopes from such sellers.

[Martin72]

I also think these are returns/grey imports that are being sold off there.
That's why the brand name has been omitted.

[ptluis]

...
Mine is from this link and is working fine.
It came with Chinese power cord, which can be replaced and with Chinese menu, which can be switched to English or any other supported language.
I bought it for about 380 euro, including the shipping, from the EU warehouse, now it is under 340 euro with a coupon...

Same with mine, purchased almost a year ago -- it's working without any problems. Interesting fact: The current offer lists the power brick not included, maybe that's the reason for the lower price. Maybe these are really manufacturer rejects that get shipped incomplete due to a QC failure? Just wondering...

And maybe that's the reason of problems with such scopes from such sellers.

Mine burn in 10 minutes...

[dietert1]

Today we got a DHO924S that we ordered yesterday. It does decode I2C - which fails on another Rigol we have.
Image shows measurement of a 22 mV signal from the built-in generator. I made an attenuator with a 50R and a 1K resistor, so the signal at the scope input is 1 mV. The image looks good, but a video would reveal more low frequency noise. Trigger is stable with that small signal. Nice tool!
I managed to download a firmware update, something that also failed with the other Rigol.

Regards, Dieter

[dietert1]

Upgrade and subsequent self-calibration have been finished. Today i got this nice FFT check, so that appears to work as well. For that i changed the signal generator waveform to rectangle. With the new firmware the diagrams got those x and y axis labels that weren't there before. One can turn them off under Menu -> Display.

Regards, Dieter

[nightynight]

Hello everyone, I'm in the process of troubleshooting a DHO804 oscilloscope. I'm trying to identify the integrated circuit marked in the attached photo — it's located near the USB-C port, in the corner of the board. Does anyone recognize this IC or know what voltage should be present at the marked test point? Based on the surrounding components, I suspect it's a buck regulator, but without a second working unit for reference, it's hard to determine the expected output voltage. Any insights would be greatly appreciated.

[zelectronicauy]

It's a NB680gb from MPS
https://www.monolithicpower.com/en/nb680.html?srsltid=AfmBOophQA-gj_hHKE2nS0nuOrFQanKn1zTm925VQ_3c7Tv0xzWEGGyz

[norbert.kiszka]

I measured all those three point on my DHO924S.

Those series quite often has cold joints. Try to resolder this IC with leaded solder and with some good flux. Maybe also other smallest components around it.

[nightynight]

Thank you all for your support. I’ve desoldered the IC — it has a short circuit between VIN, SW, and PGND. I’ve placed an order for a replacement, but due to limited availability, I was forced to source a few units from a well-known online marketplace starting with 'A'.

[vik-lob]

 
Please tell me what kind of microcircuit is circled in red?

[norbert.kiszka]

For 99% this is LDO for ADC.

[vik-lob]

Can anyone tell me the datasheet for it?

[any1ne]

Maybe someone knows?

Maybe MPQ8904DD?

[vik-lob]

Looks very much like the truth. I'll check the pinout on the board and give a report. Thanks in advance.

[vik-lob]

The MPQ8904DD chip corresponds to the chip on the T3SJ board. (In the photo above).

[vik-lob]

I soldered a 330 kOhm resistor on top, to the resistor near the microcircuit (19C). And the voltage returned to normal - 1.2 V.

[jackcheng]

HI AndyBig,

How did you increase the bandwidth to 420Mhz? I have update the vendor.bin to model 924 and enable all the option. But only get about 250Mhz (1.4ns rising time).
Could you share how did you do this? Is it related to inductance?

[SP3TA]

 There is some info on Russian forum, that decreasing inductances in front of ADC (all 4 of them - this is CLCL balanced lowpass, see photo: two channels on the right are modified) to 12nH* will rise BW to about 500 MHz - at least at 446MHz is on the similar level, than 100MHz, for reference.

* exact PN used: Murata LQW15AN12NJ00D



But I have another question: Has anybody identified all DC converters IC powered directly from USB-C connector? I'm building converterless battery pack and wondering, if I should play safe and stick to 3S configuration, or use 4S with 16.8V on fully charged pack. 🤨

[norbert.kiszka]

Some DC-DC converters are powered directly from USB-C and some are after one transistor which is used to power on/off (almost) whole scope.

From what I seen on this forum, 15.5 V is the maximum safe voltage. 12 V makes those converters less noisy and more efficient.

I suggest to use LiFePO4, because those are much much safer.

If You want to modify or bypass LC filters, You need to maintain proper line termination, otherwise You will have bad pulse response and reflections.