BK PRECISION 4051 Multi-Function Generator

[ADC-1995]

I just purchased BK PRECISION 4051 Multi-Function Generator. Its being shipped and I should have it in the next couple of days. It is discontinued and was priced at $1125. Here are the general functions and decent specs:

20MHz Sweep Function Generator
35MHz Universal Logic Probe
80W Triple Output Switching Power Supply
Auto-ranging Voltmeter
Auto-Ranging Frequency and Totalize Counter

http://www.tequipment.net/BK4051.html

Has anyone had experience with this model?

[ADC-1995]

I received my used unit today and it was in decent shape. I heard a some rattling pieces inside the case. So I wanted to see what it was ("Lets take it apart!") 4 machined screws removed from the base and the unit was open. It turned out it was some type of plastic swarf and the boards looked to be in great shape. I removed the swarf, reassembled, and power it, and NOTHING. The screen was lit up with every imaginable option and froze. DOH!

Powered off-on-unplugged and toggled power to dissipate caps-plugged in again and nothing and still locked. I noticed a reset button on the front panel, thought why not and stuck a paper clip in. Then it booted up and has been working perfectly.

[ADC-1995]

A feature available on this MFG is the DVM. The problem was it did not come with a probe and nothing was available online for this mini Din S-video connector. So I contacted BK and they were really helpful and the tech researched the product and came to a dead end. So we started reviewing the pin out and he said it looks to be the same as an S-video adapter. I had one laying around and plugged it in and it fit. He also send me a schematic of the 4051 to verify pin out!! Talk about customer service, that was great. I will post that also for a reference.

I did notice on my 0-scope noise was generated with the MFG signal and I want to repair it in the future. Anyone have any idea where to start?

Anyhow for $240 its hard to beat. The MFG appears to be built from 2004 and up, additionally the supported the MFG until 2011.

[ADC-1995]

The seller has another for sale and I have no association with this seller other than purchasing my 4051 discussed in this review.

http://www.ebay.com/itm/BK-PRECISION-4051-Multi-Function-Generator-with-Manual/221995070751?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D34494%26meid%3Dbb5fcb2ed50b4732ac11dfcc8eb03889%26pid%3D100011%26rk%3D1%26rkt%3D1%26sd%3D221988022503

[ADC-1995]

 BK 4051 Logic Probe Lead 30Mhz

This probe lead is currently not available, so I need to try and figure out what part of the logic probe is contained in the hand held lead before connecting to the internal circuit. I am trying to identify the electrical construction of this logic probe lead. This probe is not independent of the 4051 and according to the specifications, there is some type of  'protection' circuit within the probe (which I need to build) prior to accepting the signal input. However, it is also used with the DVM feature when switched to the DVM mode.

The attached schematic is a bit grainy but that is what BK provided. It is page 2 of the schematic and I think I am on track. If the internal circuit of the logic lead probe can be identified it should be an easy assembly. Any Logic Probe advice with this chip set would be helpful.

[radhaz]

Looks familiar:
http://infoscantech.com/IST-5800.html

[ADC-1995]

I did notice on my 0-scope noise was generated with the MFG signal and I want to repair it in the future. Anyone have any idea where to start?

I tested the signal on some cheapo leads. That was the problem, the MFG has solid signal quality out of the BNC.

Looks familiar:
http://infoscantech.com/IST-5800.html

Wow, Its identical, in every way except the name. The brochure is virtually exact except pictures, even the error regarding dimensions length has the same type-0 at 53".  I wonder if BK sold this design for IST  line. Thanks for the lead.

[joeqsmith]

Dang, it's a whole lab in a box.   

[ADC-1995]

Looks familiar:
http://infoscantech.com/IST-5800.html

I contacted IST and they now make this MFG and retails for $1200. I told them I was interested in the probe and they quoted me $70 which is a bit higher than I wanted to spend. I think it will be an option that I will need to watch on auction or build the probe.

[Muxr]

Function generator, power supply, logic analyser?, voltmeter and frequency counter all in one. Pretty unique piece of gear.

[Performa01]

The inputs are similar to a primitive scope, with an input impedance of 1Mohm // 50pF, VIN1 dc coupled, VIN2 ac coupled at fc ~ 1Hz.

Basic input protection up to 500VDC is already there.

I would build an adapter, Mini-DIN(m) to BNC(f), where you can connect a cheap oscilloscope probe, preferably one that is switchable between x1 and x10.

[ADC-1995]

The inputs are similar to a primitive scope, with an input impedance of 1Mohm // 50pF, VIN1 dc coupled, VIN2 ac coupled at fc ~ 1Hz.

Basic input protection up to 500VDC is already there.

I would build an adapter, Mini-DIN(m) to BNC(f), where you can connect a cheap oscilloscope probe, preferably one that is switchable between x1 and x10.

Thanks for the feedback. So the probe tip is coupled to VIN1 and VIN2, that would make sense. Therefore which ever feature selected on the MFG (Logic or DVM) would then set the probe's internal circuit to the appropriate input value you want to test?

I found a picture of the probe. Not sure purpose of LED. Possibly logic levels??

[alsetalokin4017]

Looks like 74LS374 to me.

Check the data sheet, note the number of pins and the pin designations on your schematic.

[Performa01]

Thanks for the feedback. So the probe tip is coupled to VIN1 and VIN2, that would make sense. Therefore which ever feature selected on the MFG (Logic or DVM) would then set the probe's internal circuit to the appropriate input value you want to test?

I found a picture of the probe. Not sure purpose of LED. Possibly logic levels??

No, your probe circuit doesn't make sense, nor does the connection to both VIN1 and VIN2 at the same time.

You want either AC or DC coupling, so you could make a switchable adapter that connects the center pin of the BNC(f) to either one of the two inputs.

Regarding the probe, the diode absolutely doesn't make any sense here. It would obviously prevent you from measuring low positive voltages and negative voltages at any level up to the reverse breakdown of the diode, and it would introduce some serious offset error on higher positive voltages. For the same reason the distortion on AC waveforms would be incredibly high.

If the diode were a LED, it would never light up at logic levels, because you need some 215V in order to get 1mA of DC current through it - if the input circuit you've shown earlier is correct, that is. And then what would be the point in having a fancy instrument if the logic probe is nothing more than a LED that has to be powered from the signal itself?

What you've shown here, could be a stand-alone logic probe. Instead of connecting the probe output to both inputs of the MFG, just connect it to circuit ground. With a 1k resistor the LED would turn on if the probe tip touches a logic high level in a >3V logic system.

For a DVM probe, as stated before, you cannot have a diode in series and you don't need another resistor either, as a x1 probe will have some intrinsic resistance in its lossy cable, and a x10 probe will have a 9M resistor in series anyway.

As for the logic probe, maybe there are more pins of the mini DIN connector to be used for that? In any case I would expect the logic level indication to be on the MFG, otherwise I really cannot see a reason why not to use a stand alone logic probe as they have been common some decades ago.

[ADC-1995]

Dang, it's a whole lab in a box.

Function generator, power supply, logic analyser?, voltmeter and frequency counter all in one. Pretty unique piece of gear.

So far the measurements aren't  bad for general testing.

[ADC-1995]

I found a picture of the probe. Not sure purpose of LED. Possibly logic levels??

No, your probe circuit doesn't make sense, nor does the connection to both VIN1 and VIN2 at the same time.

You are correct. I see my error in my simplistic drawing. I though there might be an internal circuit change as you toggle from DVM to Logic testing.

You want either AC or DC coupling, so you could make a switchable adapter that connects the center pin of the BNC(f) to either one of the two inputs.

Regarding the probe, the diode absolutely doesn't make any sense here. It would obviously prevent you from measuring low positive voltages and negative voltages at any level up to the reverse breakdown of the diode, and it would introduce some serious offset error on higher positive voltages. For the same reason the distortion on AC waveforms would be incredibly high.

That was suppose to be an LED that didn't turn out so well. I had to hand draw in the “emitting” portion in the probe. I should have posted it up on KiCAD.

If the diode were a LED, it would never light up at logic levels, because you need some 215V in order to get 1mA of DC current through it - if the input circuit you've shown earlier is correct, that is. And then what would be the point in having a fancy instrument if the logic probe is nothing more than a LED that has to be powered from the signal itself?

Exactly. That is what I am trying to determine. I would hope not as unit itself costs $1100 and should integrate with the options better. I hope.

What you've shown here, could be a stand-alone logic probe. Instead of connecting the probe output to both inputs of the MFG, just connect it to circuit ground. With a 1k resistor the LED would turn on if the probe tip touches a logic high level in a >3V logic system.

This is what I am thinking it is also. They keep using the term “Universal Logic Probe” for reference. The manual states to adjust the MFG to TTL or CMOS when using the probe. What I have found is I cannot select either option which makes me think two thinks. Its either not sensing the probe and does not give the option of either state or the “Logic” button/feature is broke on the MFG (hence put on ebay).

For a DVM probe, as stated before, you cannot have a diode in series and you don't need another resistor either, as a x1 probe will have some intrinsic resistance in its lossy cable, and a x10 probe will have a 9M resistor in series anyway.

I went back and ohmed out the o-scope (150hz) cable and I have a x1 resistance of 290 ohms and x10 resistance at 9 Meg as you stated. It worked fantastic with the DVM. I like it much better than my S-Video cable.    I attached a pick of my self-adapted Din to BNC. It was for testing but if I keep it I will clean it up a bit.

As for the logic probe, maybe there are more pins of the mini DIN connector to be used for that? In any case I would expect the logic level indication to be on the MFG, otherwise I really cannot see a reason why not to use a stand alone logic probe as they have been common some decades ago.

Agreed. The upper left and bottom left pins are for the DVM. The upper and lower right dont do anything for providing measurements. I ran a wire and tried to see if the MFG would sense voltage it might respond with some reading and it didnt. Nothing changed and possibly the two right pins are not working or they only work with the probe attached or the logic feature is broke. I am thinking latter.