Hy huys.
I have just built a SMPS using the attached shematic.
The problem is that instead of +/- 37 v i have +/- 60 v on the output.
R5 smokes up every time i power on the smps.
R5 is 460 ohm instead of 510 on the schematic
R7,15 are 1.8 ohm instead of 2 ohm on the schematic.
This 3 components i could not find like in the shematic. The rest is just like in the schematic diagram.
Could those 3 values that are not exact cause the fault ???
Thanks in advance for help.
I have just built a SMPS using the attached shematic.
The problem is that instead of +/- 37 v i have +/- 60 v on the output.
R5 smokes up every time i power on the smps.
R5 is 460 ohm instead of 510 on the schematic
R7,15 are 1.8 ohm instead of 2 ohm on the schematic.
This 3 components i could not find like in the shematic. The rest is just like in the schematic diagram.
Could those 3 values that are not exact cause the fault ???
Thanks in advance for help.
well, you have a lot of current going through that poor diode, no wonder it's smoking. You want the diode in the optocoupler to pass just enough current to get the duty cycle correct for the LM3524.
Make sure that the transformer is hooked up correctly. It's not hard to screw up the orientation of the leads in an SMPS power transformer unless you have wound it yourself.
If you are not going to isolate the primary and secondary -- you have them connected through 150R, you might just want to abandon the optocoupler anyway and feed the error amp from a resistive voltage divider attached to the positive leg.
Make sure that the transformer is hooked up correctly. It's not hard to screw up the orientation of the leads in an SMPS power transformer unless you have wound it yourself.
If you are not going to isolate the primary and secondary -- you have them connected through 150R, you might just want to abandon the optocoupler anyway and feed the error amp from a resistive voltage divider attached to the positive leg.
I'm not sure to be of aid but try to contact me privately i've just build this SMPS with some variation...
Mail: maxiz@inwind.it
ICQ: 47573544
DIY thread: http://www.diyaudio.com/forums/showthread.php?s=&threadid=19107
Mail: maxiz@inwind.it
ICQ: 47573544
DIY thread: http://www.diyaudio.com/forums/showthread.php?s=&threadid=19107
Here are some ideas
first, I drew in a couple black circles to indicate the polarity of the transformer windings.
second -- there should be a resistor on the compensation network -- poles and zeroes you know
third -- the divider to the inverting input of the error amp should provide (you can adjust it) 2.5V at 37 volts, equalling the 2.5V from the reference voltage divider
fourth -- forget about isolating the two halves, use the same ground (I didn't take it out)
first, I drew in a couple black circles to indicate the polarity of the transformer windings.
second -- there should be a resistor on the compensation network -- poles and zeroes you know
third -- the divider to the inverting input of the error amp should provide (you can adjust it) 2.5V at 37 volts, equalling the 2.5V from the reference voltage divider
fourth -- forget about isolating the two halves, use the same ground (I didn't take it out)
Attachments
If you don't have haste i'll post the schematic tonoght (for me) modifyed that i've build and run correctly.. anyway check if the buz become very hot in few second if so the problem is on the transformer.. Check that the winding are winded correctly, to cover all the surface.
Don't think i'm an expert but with the experience i've learned something...
I hope to be of help!
d
Don't think i'm an expert but with the experience i've learned something...
I hope to be of help!
d
My final schematic of SMPS!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Ford_V6,
This is similar to the PS I use in my gear.
Without giving it a full look over, something is definately wrong. Based on the values of the Zeners, it should limit to approx 70-75v across the rails.
Assuming that you have already double checked your work, I would have to say that you either have a bad component (A4N35?), wrong Zener values, or an incorrect design.
If you get it to work, I would reccomend a 47uf/16v cap across R20 to help minimize the on/off poping (- toward GND of course).
By the way, what the heck are you trying to power up that you need (6) Buz11's??
------------------------------
Learn it, Know it, Live it.
------------------------------
-CJB-
This is similar to the PS I use in my gear.
Without giving it a full look over, something is definately wrong. Based on the values of the Zeners, it should limit to approx 70-75v across the rails.
Assuming that you have already double checked your work, I would have to say that you either have a bad component (A4N35?), wrong Zener values, or an incorrect design.
If you get it to work, I would reccomend a 47uf/16v cap across R20 to help minimize the on/off poping (- toward GND of course).
By the way, what the heck are you trying to power up that you need (6) Buz11's??
------------------------------
Learn it, Know it, Live it.
------------------------------
-CJB-
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.