Hello guys, I have some equipment that uses a control board in which the original HEF4093 ICs burned and in place I put a texas CD4093BE. However, the circuit does not work correctly. I don't know much about electronics, but someone can help me.

What would be the function of the 200pf capacitor connected to the ground and the U17C?

On one side of the capacitor is gnd 0V, on the other is it if I had nothing connected to the U17 input?

 

Hello,

I would have expected the pins 8 and 9 being connected, to create a delay circuit.

Bertus

 

Yes I agree it should be joined to pin 8 to make a short pulse with R81, to trigger the timer.

 

U17 would be an oscillator if it had a resistor from its output to the input with the capacitor.
As shown, that input has no important DC high or low.
Here is a Cmos Schmitt Trigger oscillator:

 

I”ll join the chorus; it must be a drawing mistake on the schematic.
On the board itself, check exactly how the device is connected. As Bertus mentioned, very likely pins 8 and 9 are connected together.

 

The diagram really lacks the connection between the 8 and 9 of the U17C, but the board is interconnected

The CD4093 is used position U17, U12 and U1.

Looking at the complete schematic does anyone tell me something that makes the Cd4093 from texas purchased from farnell not working properly?

 

hi
The HEF series is a much faster device than the CD4000 series, it may be a timing problem.

E

 

What would be the function of the 200pf capacitor connected to the ground and the U17C?

I agree with the others that there is a missing connection.

I don't put much stock in schematics drawn like that. Connection dots with wire humps and unnecessary wire bends are signs of someone who doesn't know what they're doing. Of course, some schematics are drawn by drafting people who know nothing about electronics...

 

If U17C is supposed to be a pulse generator with R81/C31, then D23 is also connected backwards.

 

I never connect two Schmitt Trigger inputs together like that to make a Schmitt Trigger inverter.
Since the input with the capacitor has no DC voltage reference then I guess some ICs will work and other ICs will not.

 

A detail that may help to solve the problem:

The equipment even works, but when the power is increased the LD8 Q-up limit must light up and not allow the power to be increased.

With the old IC the led lights up and does not increase the power anymore, with the new IC the led also lights up but the power continues to increase.

 

O esquema tem um erro, na placa real os pinos 8 e 9 estão conectados.


Mod: translate.
scheme has an error, on the real board pins 8 and 9 are connected

 

Problem update: The board uses the 4093 in position U1, U12 and U17. I did a test with some old ICs of the ST HCF4093BE, and that the CD4093BE of Texas does not give problem in the position U1 and U12, only in the position U17, in that position I left that of the ST and it is working.

However I have other cards and it is no longer manufactured in HCF4093BE in DPID-14

Where in U17 is the problem? No U17A, B, C or D?

Is changing the value of any component or making a change in the circuit with you a solution?

Remembering that pin 8 and 9 of U17 is physically interconnected, in the diagram no.

 

Problem update: The board uses the 4093 in position U1, U12 and U17. I did a test with some old ICs of the ST HCF4093BE, and that the CD4093BE of Texas does not give problem in the position U1 and U12, only in the position U17, in that position I left that of the ST and it is working.

However I have other cards and it is no longer manufactured in HCF4093BE in DPID-14

Where in U17 is the problem? No U17A, B, C or D?

Is changing the value of any component or making a change in the circuit with you a solution?

Remembering that pin 8 and 9 of U17 is physically interconnected, in the diagram no.

if D23 is connected like the diagram, it is wrong. It is connected backwards. The anode should be connected to pin 8.

 

Check on the board and the diode D23 is mounted as in the diagram.