SST03 problem

[h3ndrix]

heaveno,

I have a problem with the SSt03 soft start. I tested with 24V and then with 230V, what happens is the output receives voltage for about 500msec and then loses the voltage. This happens everytime. I put a jumper in place of the switch and have a basic green led at the LED position. How can I troubleshoot the board? thank you.

[peranders]

Have you used my BOM or any difference? Did it work with 24 V DC?

[h3ndrix]

Hi,

There are some differences in the BOM, as I was not able to gather some of the parts, here is what I used instead:

- The 330nf 275V caps are ECQ-UAAF334K caps which are polypropylene
- The 1uF 63V caps are Epcos B32529C105J poly film
- The relays are Finder 41.52.9.024.0010 which are 24V 8A relays but are short-type

The other items are as you specify in the BOM.

[peranders]

If you connect 24 V DC to the rectifier bridge, will not even K1 active?

[h3ndrix]

No, no, I think I was not able to explain it well...both the relays seem to work, I hear both the relays "click" , but when I tried it with a basic 60W light bulb and when I connected a switch and turned it "on", the light bulb turned on for ~500msec and then turned off, the LED of the circuit stays on, I also feel some heat at R6-R7-R8-R9 (they burn my fingers) and DZ1.

[peranders]

Did you touch the resistors with 230 VAC applied? If yes, LETHAL. Don't do that. Where do you connect the bulb? The terminal for a LED should be shorted if you don't use a LED. Nothing else should be connected there.

Does the K1 activate and stays in this condition?

500 ms later K2?

[h3ndrix]

I connected the light bulb to the mains output, to see if the circuit worked. I connected a green led to the LED terminal, the led works fine, but the light bulb only works for ~500msec.

[peranders]

What happens then? Low voltage or no voltage?

[h3ndrix]

no voltage

[peranders]

Are the relays activated? Voltage across the coils?

[h3ndrix]

Both the relays have 3.2V across the terminals when 220V is applied. I also hear a very light buzzing.

[peranders]

How much du you have after the rectifier? Do you really have 330 nF? Not 33nF? A picture would be good. It seems that you don't have the right parts.

Does it work properly when you have 24 VDC applied?

[h3ndrix]

Yes, they are 330nf, did you see the parts in my second post?

[peranders]

Do you really have 4 x 120 ohms in series? Voltage across them? If it works correctly with 24 VDC you know that the fault might be in the capacitor circuit before the rectifier bridge. I'll recommend that you debug the circuit with 24 VDC first.

[h3ndrix]

heaveno again,

I checked the resistors again, they are all 120 ohm, very high quality vishay resistors, 1% type. The voltage I read across the 120 ohm resistors is 22V on 230V mains. I also checked each finder relay with 24V from DZ1 and individually, the relays seem to work, they make the "click". I measured the 330nf caps on 230V main voltage, both the caps read 230V. What else should  I check? Thanks.