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Hantek MSO5102D

 
crustytv
(@crustytv)
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I have a bit of a soft spot for test equipment and in particular scopes, so any excuse to get one and I'm there. Over the years I've had many analogue scopes from a huge boatanchor Solatron CT46 , Telequipment's and of course Tektronix. Eventually I moved over to DSO.

I started off dipping my toe in with the colour OWON PDS5022s 25MHz 100s/s. As an entry level scope its was OK, the screen not great and there wasn't any USB capture but it was perfectly adequate and served me well on my TV repairs. Always being a bit of a Tektronix fanboy, my next acquisition was a mono Tektronix TDS1002 60MHz 1GS/s. Now this blew the OWON out of the game a much better scope despite being much older. Next came the chance to get my current workhorse a new colour, widescreen Textronix TBS1052B 60MHz 1GS/s. As I say this is my main scope and I absolutely love it. OK its under 100MHz but for the most part that's all I need for the type of work I get involved in.

So like me, you might think that's where it stops, other than perhaps spending a small fortune and getting a much faster TEK. Well I thought so too however dipping into the world of 1st generation Laserdisc players, the introduction of IC madness and microprocessors with all their inherent "Low" "High" or binary 1 and 0's malarkey, set me off once again.

It started because of working on the Pioneer LD1100 fault and hitting this "new to me" state of "low and high". Without any prior experience or detail in the manual to assist with what is "High or Low", I was left baffled. John kindly pointed out that "H" was roughly 4V and above, "L" roughly 1V and below. The problem being trying to check this all out with multimeters was far from ideal. I tried hooking up the three DSO's and that was as far as I got in trying to diagnose what states the various chips were in and why I was not getting focus lock and spindle drive.

Then I had a thought, what about getting an MSO (Multi Signals Oscilloscope) basically a DSO with a built in logic analyser. OK It might be overkill, It might not tell me anything or I might be too stupid to know what its telling but I decided why not. So I've bit the bullet and bought a HanTek MSO5102d, a colour widescreen 100Mhz 1GS/s MSO. Good thing is it hackable, this means I can update the firmware making it a 200MHZ MSO. Basically all the product range are the same and its just a software setting that drops the speed. It needs to be done carefully, taking a backup of the machine just in case but from what I've read over on EEVblog it works well.

Anyway back to the main reason for buying it, being an MSO it also has a built in 16 channel logic analyser. A logic analyser doesn’t measure analog details, instead it detects logic threshold levels. It looks for just two logic levels, when the input is above the threshold voltage (Vth), the level is said to be “high” or “1” conversely, if the level is below Vth “low” or “0”. Now that to me will certainly help as mentioned above, I’ve struggled to know exactly what state the various circuits were in and what in the pioneer is considered Low (0) or High (1). This in theory will at least clearly show what states the various parts of the pioneer are in.

Bit of a learning curve coming up with regards to setting up the LA side of things and how you get it all to trigger.  I'm hoping this should allow me to now not only simultaneously see what various waveforms are present, but also the important logic states of this Pioneer Laserdisc problem.

And if not? Well its another toy ........

mso 1
mso 2
mso 3
mso 4
mso 5
mso 6

 

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Topic starter Posted : 29/05/2019 11:09 am
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Terry
(@terrykc)
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Posted by: crustytv

... however dipping into the world of 1st generation Laserdisc players, the introduction of IC madness and microprocessors with all their inherent "Low" "High" or binary 1 and 0's malarkey, set me off once again.

It started because of working on the Pioneer LD1100 fault and hitting this "new to me" state of low and high. Without any prior experience or detail in the manual to assist in what is High or Low I was left baffled. John kindly pointed out that H was roughly 4V and above and L rough 1V and below.

... It looks for just two logic levels, when the input is above the threshold voltage (Vth), the level is said to be “high” or “1” conversely, if the level is below Vth “low” or “0”. Now that will to me will certainly help as I’ve struggled to know exactly what state the various circuits were in and what in the pioneer is considered Low (0) or High (1). This in theory will at least clearly show what states the various parts of the pioneer are in.

Bit of a learning curve coming up with regards to setting up the LA side of things and how you get it all to trigger.  I'm hoping this should allow me to now not only simultaneously see what various waveforms are present, but also the important logic states of this Pioneer Laserdisc problem.

What is most likely to confuse you, Chris, is that different logic families have different logic level limits!

Although they come in identical black packages, the circuitry needed to achieve the desired objective is completely different inside those packages. You are well accustomed to handling valve and transistor circuitry, sometimes in a hybrid piece of kit but you instinctively know that that big glass bottle can't possibly be a transistor anymore than a microscopic metal can or three legged blob of plastic can be a valve, and treat each differently and appropriately, probably without even realising it. 

All TTL (and LSTTL) is operated from a 5V supply and, with the exception of those with open collector outputs, conform to the same set of logic levels.

CMOS devices, however, can operate over a wide range of voltages, typically 3V to 15V, and the logic levels are relative to the supply voltage. Even at 5V, though, these limits differ from TTL limits. Both families can operate together though, if absolutely necessary, if care is taken in the interfacing.

If you find all of this somewhat daunting, fear not, I'm sure the information contained in this article will explain the situation much better than I ever could!

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Posted : 29/05/2019 12:14 pm
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crustytv
(@crustytv)
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Hi Terry, 

Thanks for that and also the link, very useful, I shall swot up on all it has to offer. ? 

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Topic starter Posted : 29/05/2019 12:36 pm
Terry
(@terrykc)
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Chris, one thing that might be confusing you is that you are used to measuring analogue voltages, looking for suspiciously high or low values. With digital circuitry, all you are interested in is the logic level, irrespective of what the actual voltage is. 

Ironically, an analogue device is better for analysing logic levels than a DVM!

Assuming TTL or CMOS fed from a 5V supply, take a 'scope, set the zero reference to the bottom of the screen and sensitivity to 2V/cm so that the top of the screen is 5V.

Now use you probe to check the output of various gates. If they are TTL, if the 'scope reads one division or less. it's a logic 0. If it reads one division above the centre line or higher, it's a logic 1. Anywhere in the no-man's land between these levels needs investigation.

CMOS gates will, of course, show levels of (virtually) zero and (virtually) 5V but the principle is the same.

You might say "Ah! But the minimum input to a TTL gate for a logic 1 is 2V and that's below the centre line!" So it is, but it isn't right - the difference between the input and output levels is purely intended to ensure a clean switching action. The inputs of most gates are directly connected to the output of another gate. If the output of that gate is correct, the input to the next gate must be the same - 2.7V or higher!

The same reasoning applies to CMOS gates.

Remember, Chris: Think Logic, not Voltage!

It's not as difficult as it looks!

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Posted : 29/05/2019 2:45 pm
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crustytv
(@crustytv)
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Well one week on from purchasing the Hantek MSO5102D I'm pleased with it. The Logic analyser side of the MSO was put to good use to observe the focus signals generated on a recalcitrant laserdisc player.

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Topic starter Posted : 05/06/2019 11:23 pm
Nuvistor
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Logic Analyser, not seen one for years, occasionally had to use one in capture mode when looking for very intermittent problems. I would probably have great difficulty in using one now.

 

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Posted : 06/06/2019 7:36 am
jjl
 jjl
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I use logic analyzers from time to time in my professional life, but nowhere near as much as back in the '80s.

These days, I'd typically use one to look at a SPI interface i.e. with clock, select and serial data in and out lines - modern LAs have the ability to decode serial data as seen on SPI or I2C.

In the '80s they would often be used to capture all of the bus signalling of a microprocessor and would be able to disassemble the instruction stream of whichever processor was in use. Hewlett Packard quaintly called this "inverse assembly" at the time. With modern processors, the signalling is either much too fast to capture with anything other than stratospherically priced instruments or in the case of system on chip devices the signals you'd like to look at don't leave the processor package at all and you can't get at them.

 

John

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Posted : 06/06/2019 8:20 am
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