SSR01 problem

[Simon]

Hi

I have built three SSR01, and the 15V one is dine, but both 5V LM431 output 9.19V.

I have checked and rechecked the component list against the circuit diagram and they look ok. It outputs 9.19V regardless of inout voltage, so at least it is regulating!

The LM431 is installed as per the bold outline on the PCB.  Voltage drop at the LM431 is 2.49V

Any suggestions would be appreciated...

[peranders]

Are the SENSE connections tied to output and ground?

Used opamp, type?

Input voltage?

Voltage at the opamp

Pin 7
Pin 2
Pin 3

[Simon]

Hi

Yes, the sense connections are tied to output and ground - I have soldered the pads at the relevant points

The opamp is AD825, I purchased the boards with the opamps ready soldered.

Input voltage has been varied from 12v to 24v (I am using a bench power supply to test prior to installation).

The voltages at the opamp are:

Pin 2 = 4.57v
Pin 3 = 2.5v
Pin 7 = 11.38v

thanks

Simon

[peranders]

Since I use an iPhone I don't have the schematic. The opamp isn't active. The pin 2 should be at the same voltage as pin 3.

The transistor conntected to the opamp, do you have 0.7 V between base and emitter?

[Simon]

Do you mean Q2 or Q3?

[peranders]

The transistor which has it's base connected to the opamp output.

[peranders]

Ssince both regulators don't work I'll suspect a systematical error. Please check my photos very carefully.

[Simon]

Hi

I have checked against the photos, and they all look ok, with the exception that I have used a zener diode at DZ1 (instead of the LED in the photo and it is orientated correctly if I look at your other photos with the zener in this position) and R12. I have used a 470ohm resistor at R12 as per the cct diagram, but in the photo, it certainly does not look lie 470ohm - can you please confirm the correct value?

Also, can you please update the photo of the SSR02  -15V LM329? It is of a SSR01 at the moment.

thanks

Simon

[Simon]

Hi

Some good news, I have replaced the zener with the LED and it now works ok.. The BOM, etc could do with a note as it notes that either can be used and that appears to not be the case...

[peranders]

Glad to hear that you have solved the problem but the BOM states this in the Excel file  BOM-ssr01r0(5V, LM431).xls