owon: OWON two channel 100MHz Oscilloscope SDS1102: Brief review 3

In order to list the active components use in this equipment, I have done a complete teardown.

The two aluminium heatsinks covering two LSI chips are hiding the FPGA and the ADC.

The FPGA at position U7, is a popular Xilinx Spartan-6 XC6SLX9.

The ADC at position U45, is a Analog Devices HAD1511, 8-bit, 1 gSpS, A/D Converter, single/dual/quad channel. It uses the U46  8V97051 Wideband RF Synthesizer/PLL VCO to sample the analog signals coming from both vertical channels U53/U55 AU1A (similar to LMH6551) Differential High-Speed 370MHz Op Amp.

Besides the LMH6551 opamp, each vertical analog amplifier uses a SG5KA (similar to SGM8271) High Voltage Rail-to-Rail Output Operational Amplifier, a HVB  (similar to AD8337) DC COUPLED variable gain amplifier, a 3157 (similar to SGM3157) Single-Pole Double-Throw Analog Switch, a 3EM (similar to MMBTH10) NPN VHF/UHF transistor, a 52X (similar to BAV99) FAST SWITCHING DIODES for circuit overload protection, a 2AW (similar to BF862) N-Channel JFET, and a NEXEM UD2-4. 5NU RELAY.

Additional active components for auxiliary functions are seen in the main PCB, like a a C116S1 (similar to TPC116S1) 16-bit DAC, a SGM48751YS16 8:1 CMOS Analog Signal Multiplexer, two TP2274 ICs 36V CMOS OPAMPS with 4 opamps each at 7MHz bandwidth, and a bunch of NPN and PNP fast swirching transistors (mostly LY/KTC4075  and SY/2SA1162.

Quite a lot of local power supplies are used in the main PCB, on both sides, required to generate the different operating voltages of the active circuits. This approach optimizes the power decoupling and filtering, while allowing to use a single 15 Watt, 5.5 Volt, Switching Power Supply on a dedicated PCB.

This 5.5V SPS runs from 100-240VAC that is rectified by the BR1 JF ABS8 0192 (800V, 0.5A, 30A peak) full bridge, and uses a PN8149 8-pin PWM controller with power MOSFET IC that can handle a maximum of 24W, driving a step-down transformer (ref. 0201-0643). The loop uses a PH1 EL817 B017 4-PIN PHOTO-transistor coupler.  A single D3 SEMIKRON K45 R15  power switching diode (SK45 --> 4A, 50V) and three capacitors shapes the 5.5V output to power the Main PCB and KEY Board PCB.

 

The Main PCB, upper side, having the IC's heatsinks and Analog Amplifiers shielding removed:

 

Analog amplifiers exposed after removing the shield:

 

Main POCB under side:

 

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Dear Jore,

thanks a lot for giving us an insight into the OWON Oscilloscope. I have one in my workshop and made good experience so far. It is small and light weighted and has a good price/performance relation. For me the maximum limit of 400 V DC is for repairing of valve radios an interesting feature which is not given for most modern Oscilloscopes. 
For me it is fascinating to see the development of technology compared to first electronics from the 1920ies. 

Rüdiger 

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Dear Rüdiger ,

Thank you for your comments.

Indeed, the digital oscilloscopes changed the way we used to interact with a good old analog CRT oscilloscope. I still use my vintage humble Centrad 272e to read composed signals (modulated, video) that are easy to trigger with it when compared to a low cost digital oscilloscope.

Overall I am happy with this OWON SDS1102, it have so many features for the price. With 50 EUR more one could buy a oscilloscope from other popular brands, for instance from RIGOL, offering even more features, like larger storage capacity, but for my needs I felt that this OWON was more than enough. 

I had a small problem with my unit just one week after receiving it. Initially it worked fine. But one day it refused to power ON like there was no AC power supply applied. Pushing the Power Switch was not giving the espected red light on the Run/Stop key. I cheked the AC voltage at the power cord, it was fine. Replaced it with another power cord, same result. Pushed the power cord IEC plug against the oscilloscope panel plug, no luck.

Then I decided to open it for inspection, but it started working again by itself. Could not find an obvious cause. The main suspect was the power switch but it measured close to zero ohms on every test. PCB fuse was OK. Power supply DC output voltage normal. No lose connectors. Just in case, I resoldered all the power supply PCB connections, from the AC input to the DC output.

It has been working fine since then.

 

Cheers,

Jose

 

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