Hmmm... what did you fit in the end, 1uf ? You could perhaps try something like a 1.2 or 1.5uf although this seems to be fiddling the fault rather than fixing the reason.
The main mechanisms a PSU would use for sensing a problem would be either measuring the mains directly and comparing it to some reference. This doesn't add up though... an SMPS surely wouldn't be designed to work over a narrow voltage range, it defeats the object. It could sense current in the switching elements via a low value resistor. Or it could look at the flyback pulse. Why would that give a no start situation though... very odd.
The main mechanisms a PSU would use for sensing a problem would be either measuring the mains directly and comparing it to some reference. This doesn't add up though... an SMPS surely wouldn't be designed to work over a narrow voltage range, it defeats the object. It could sense current in the switching elements via a low value resistor. Or it could look at the flyback pulse. Why would that give a no start situation though... very odd.
Hi,
Sorry to heard it didn't worked as expected. I would check pin 10 after you powered the amplifier. It should read zero and if it read high means that something it is telling the PS to shutdown. Also I will check pin 16. It is the reference voltage for the oscillator. The problem here it is that the datasheet do not explained how to set up the PWM. I do not know if there it is an application data sheet on how to setup the PWM. I do not like to work by guessing.
Sorry to heard it didn't worked as expected. I would check pin 10 after you powered the amplifier. It should read zero and if it read high means that something it is telling the PS to shutdown. Also I will check pin 16. It is the reference voltage for the oscillator. The problem here it is that the datasheet do not explained how to set up the PWM. I do not know if there it is an application data sheet on how to setup the PWM. I do not like to work by guessing.
The ST datasheet is a little different than the ON datasheet. Maybe page 7/12 has a clue:
https://www.jameco.com/Jameco/Products/ProdDS/1394427.pdf
This looks like a similar chip, and has more information:
Application Note Power Supply And Power Management SG3525 AN250 Datasheet Download
Maybe also look at the datasheets for the following:
SG3525 ANALOGOUS:
https://www.jameco.com/Jameco/Products/ProdDS/1394427.pdf
This looks like a similar chip, and has more information:
Application Note Power Supply And Power Management SG3525 AN250 Datasheet Download
Maybe also look at the datasheets for the following:
SG3525 ANALOGOUS:
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Hi,
Thank you Gootee for the information link. I was searching using the ST-Microelectronics SG3524P for information and always got the same data sheet. The second link have more information that may help to troubleshoot the problem.
By looking at the application note we need to find out the following pin voltages.
Pin 10 -shutdown = 0
pin 16 -reference = 5.2 volt
pin 15 -Vcc = 8 to 40
pin 5 - osc. control voltage ?????
Thank you Gootee for the information link. I was searching using the ST-Microelectronics SG3524P for information and always got the same data sheet. The second link have more information that may help to troubleshoot the problem.
By looking at the application note we need to find out the following pin voltages.
Pin 10 -shutdown = 0
pin 16 -reference = 5.2 volt
pin 15 -Vcc = 8 to 40
pin 5 - osc. control voltage ?????
Check out the detailed explanation of SG3525 pin function & operating condition from this good guy:
Tahmid's blog: Using the SG3525 PWM Controller - Explanation and Example: Circuit Diagram / Schematic of Push-Pull Converter
Drive your SMPS from an isolation transformer
Then start probing the pins of your SG3525. You’ll get an idea where the problem is.
You may need to pay attention on the feedback lines, the problem may lie at the low voltage output section (rect diodes, capacitors) of the SMPS.
George
Tahmid's blog: Using the SG3525 PWM Controller - Explanation and Example: Circuit Diagram / Schematic of Push-Pull Converter
Drive your SMPS from an isolation transformer
Then start probing the pins of your SG3525. You’ll get an idea where the problem is.
You may need to pay attention on the feedback lines, the problem may lie at the low voltage output section (rect diodes, capacitors) of the SMPS.
George
Interesting. Pin 10 grounded means the unit is on all the time. Unit came with a .1uf on the pin 8 soft start, meaning a quick-ish start, although not per spec sheet. Pin 6 has a 6.8k resistor, so within reason, unlike soft start capacitor. Have not measured the Ct cap to determine oscillator frequency, but assume all is well here anyway.
I can take the variac and start the module at around 95vac, and then, as I slowly increase the voltage, drops out at around 115vac, sometimes I can get to 122vac (my line voltage) and will stay on, which is probably why adding 1uf to the pin 8 worked sporadically.
I will take more voltages later when I return.
Happy Thanksgiving all, by the way...
I can take the variac and start the module at around 95vac, and then, as I slowly increase the voltage, drops out at around 115vac, sometimes I can get to 122vac (my line voltage) and will stay on, which is probably why adding 1uf to the pin 8 worked sporadically.
I will take more voltages later when I return.
Happy Thanksgiving all, by the way...
OK, voltages on all pins are same when operating and when shut down. Now I am confused... So its not this chip / circuit??
I did notice that the 6.8k resistor tied to pin 6 (Rt) was intermittently going to open (a bad solder joint?), causing the amp to pulse or not start, so I replaced it, and took the soft start cap and made it 1uf. Maybe that's the reason it was having issues? We are back to working properly now with the 6.8k resistor replaced and 1uf cap of soft start.
Pin voltages (DC referenced to primary ground) all look good. Like I said, even when the modules shuts down I have same voltages...
1 - 0
2 - 5.16
3 - .027
4 - .273
5 - 2.027
6 - 3.76
7 - 2.025
8 - 4.9
9 - 6.17
10 - 0
11 - 5.16
12 - 0
13 - 12.6
14 - 5.17
15 - 12.6
16 - 5.17
I did notice that the 6.8k resistor tied to pin 6 (Rt) was intermittently going to open (a bad solder joint?), causing the amp to pulse or not start, so I replaced it, and took the soft start cap and made it 1uf. Maybe that's the reason it was having issues? We are back to working properly now with the 6.8k resistor replaced and 1uf cap of soft start.
Pin voltages (DC referenced to primary ground) all look good. Like I said, even when the modules shuts down I have same voltages...
1 - 0
2 - 5.16
3 - .027
4 - .273
5 - 2.027
6 - 3.76
7 - 2.025
8 - 4.9
9 - 6.17
10 - 0
11 - 5.16
12 - 0
13 - 12.6
14 - 5.17
15 - 12.6
16 - 5.17
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