Layman's method for troubleshooting CD4016 analog switch IC help please

[yul]

Hello! I need to troubleshoot some of these IC's on a synthesizer keyboard and would need advice please.

I do not have equipment although would like to know if a basic multimeter with a small circuit tracer would be capable for this task?

I believe the available truth tables might be helpful but not sure here.

I would really need to know a quick and dirty way to check them please?

Hopefully there is a layman method. There are about 4 of these IC's

Thanks so much!!!

 

[kellys_eye]

Google the datasheet for the device.

http://pdf1.alldatasheet.com/datasheet-pdf/view/11947/ONSEMI/CD4016.html

Identify the power pins and check they are getting the right voltage (pins 7 and 14)

Identify the inputs (pins 1, 4, 8 and 11) and
outputs (pins 2, 3, 9, 10) of each 'switch' along with its
control signal line (pins 13, 5, 6 and 12).

Check that the input signal to the 'switch' appears at the output when the control signal line is active-high.

Note that these devices do not have ESD protection on their inputs so if you have to replace any take the necessary precautions for handling static-sensitive devices.

 

[yul]

Thanks!!! Would a basic multimeter based tracer signal work in this case? Much appreciated.

 

[kellys_eye]

You can check it with DC voltages if you want - the switch passes AC or DC. Use a series current limiting resistor if injecting DC (1kΩ will do). Connect the resistor from pin 14 to the input pin of each switch and check for the same(ish) voltage coming out when the gate is 'activated'.

Any standard multimeter with volts range will work.

 

[yul]

I just saw a basic circuit tester (the pen type) with one lead to ground and a LED. Would you say this would be applicable in this case? Thanks again so much this is very appreciated.

 

[kellys_eye]

In the absence of an oscilloscope, a true measurement of DC would be a better test as this will allow you to determine the switch 'on' resistance - some faults in such circuits may be caused by the switch not being 'perfect' rather than simply 'not working'.

The LED-type tester is a go/no-go test method rather than one that can reveal a switch that is only 'part-working'. Rather depends on the type of fault you're experiencing.

 

[yul]

OK in my case it's really a NO GO situation meaning total absence on functionality. Since there are 3 more similar IC's I would compare the results. Thanks again I will give it a shot and report back!! So much appreciated. Cheers

 

[yul]

Hello again !! Would you say that the current provided from a 9V battery powered multimeter with an integrated continuity tester/audio signal would requiire a resistor before testing this switch in your opinion? The datasheet says supply range is between 3.0 Vdc to 18 Vdc. Should be fine ? Would you still consider a resistor in this case? Thanks!

 

[kellys_eye]

Depends on the switch 'on-resistance' as many multimeter continuity buzzer ranges only work on sub 100Ω values (or less - check your meter spec sheet).

Best check it by measuring the DC across the switch in it's open/closed state.

 

[yul]

Very interesting!

It seems the ON resistance for this switch at 9VDC would be around 200-300Ω.
Buzzer specs are 3 volts signal around 50Ω. Doesn't sound like it would do the job..

Would you say it would be better/simpler to just probe around the switch in operation looking for DC with the meter then instead?

What about a transistor based signal tracer? Would that be helpful?

Your previous method for injecting would require meter, resistor and a battery I assume? Seems similar to the signal tracer kits then?

Thanks again so much!!

 

[kellys_eye]

You aren't understanding the principle of the 'on resistance' properly.

The value you quote (200-300Ω at 9V) is the resistance (in-to-out) of the switch if it is powered from 9V DC i.e. the chip ITSELF is powered by 9V DC. I don't know what your system (circuit) supply is but it's likely to be higher than 9V consequently the 'on' resistance will be whatever the data sheet specifies it is at those voltages.

If you used the switch as the resistance in one leg of a voltage divider (for example) you could calculate the exact expected voltage at the junction of both resistances as you would know the values of the two resistors forming that divider (one being your 'on resistance') and know for certain, by measuring the actual voltage, whether the device is operating correctly.

When it is in circuit you can only measure the value of the signal going in and out when the circuit is under power and a signal (voltage or waveform) is present at the 'in' of the switch.

If you then measure the 'out' of the switch you can check to see if the operation is correct by comparing the two measurements before and after the control voltage (to the switch) is applied.

You can force a signal (voltage) to the input of the switch - like when I mentioned to use a resistor from the supply rail and connected to the switch input - then check the output of that switch to see if that voltage appears/disappears with the application of the controlling voltage.

Equally you could take the device out of the circuit, power it up and measure the static resistance between in/out whilst applying a control voltage to the appropriate pin. The resistance should lie within the spec as advised on the datasheet.

 

[yul]

Thanks I will review your comments carefully.

It would remain in circuit (possible powered on) for the whole time and I don't know the actual circuit supply right now either. ON resistance in the datasheet go up to 300Ω in the 15 Volts range. In any case the buzzer may not work from what I understand.

It looks like a standard meter would work by doing some voltage comparison when in operation (hopefully it will).

I will experiment with my meter hopefully with some findings for now and thanks again for your precious help!!