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.
Have you used my BOM or any difference? Did it work with 24 V DC?
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.
If you connect 24 V DC to the rectifier bridge, will not even K1 active?
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.
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?
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.
What happens then? Low voltage or no voltage?
no voltage
Are the relays activated? Voltage across the coils?
Both the relays have 3.2V across the terminals when 220V is applied. I also hear a very light buzzing.
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?
Yes, they are 330nf, did you see the parts in my second post?
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.
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.
Does it work properly with 24 VDC?
What is the voltage across the zener when having 230 VAC in?
Across DZ1 I am reading:
- 3.97 V DC
- 0.79 V AC
I measured both just in case.
Also the 120 ohm resistors are reaching 78 degrees celsius...is this normal?
B1 is mounted right? Not broken? Does it work with 24 VDC?
You should have 48 mA through the caps and the 120 ohm resistors so the total power will be 0.27 W per resistor. That's OK for 600 mW resistors. You have only a few volts you say and that means that the load is too heavy. Where does the current flow? You should first check with 24 Volts with current limitation so you don't fry any parts.
I have been trying to solve the problem, I even tried to do some simulations in proteus (isis), but I get weird results:
- when the switch is open I get 30V.
- when switch is closed (circuit working) I get 163V.
An here is the switch open:
Just discovered something weird, I figured I should check if there is any continuity in the relays when the power is supplied, so I checked and there seems to be problem. It seems like the relays first work and then jump back, so thats why I get no voltage in the output. Why would that be, seems like the relays are working and then jumping back.
Have you tested with 24 VDC? D4 working? Mounted correctly?
So I finally found a AC transformer with 24V out and tried it, here is what I found:
- When the circuit is swithed ON or OFF, it doesn't matter, I get 5V AC at mains out,
- Both of the relays receive 2.78V at their coil contacts,
- The LED does not turn on, if I turn the switch on and off a few times, every once in a while I get a very fast flash on the LED (I guess thats the caps)
- DZ1 measures 2.1V DC and 175mV AC
What do you think?
Another thing I don't understand, when I try to apply 24V directly to the K2 relay coil, I get sparks, I tried both ways just to make sure I dont mix anode and cathode and its the same.
You should have used a DC source with current limitation. If you apply AC directly to the coils you may destroy the D4. I think something if not correct mounted and possibly also broken. Could you please try to get a DC source for testing? You could also take a close-up photo and upload. Maybe there is something obvious?
I applied 24V DC to the coils, not AC, as I mentioned, one of the relays work and the other does not. I will try to take a photo today. Thanks.
Voltage across R13 when you have 24 VDC?
R14?
R10?
Found it! :)
I checked the voltages like you said and found out that the resistor in R13 was broken, for some reason. I changed it and it works:)
Thanks for all the replies and help.
Good! I was a bit worried because noone has failed to get this design working.