Surprise !!!
I am actually studying SMPS, will start using them.
I´m losing lots of sales to "brick" sized Ampeg PF350/500 , Markbass and TC Electronics miniature 300/500/700W SMPS fed Class D heads so I´ll have to design my own.
I´m halfway through a *very* practical, hands-on repair manual, which now will try to post here.
Zero math, some shotgunning involved, minimal instruments, but, hey!!! , probably what "Joe PC supply repair Shop" uses on an everyday basis.
Only major point I diasagree with it is that they are somewhat kamikaze: ground scope to hot mains ground, consider an isolation transformer optional, trust home GFCI to cut power quickly before they die, claim grabbing a 310V charged main cap with both hands "may make you drop the TV or monitor you are repiring , picture tube will explode and sharp glass can cut you" but "shock is too short to kill you"
In that aspect it´s a suicide manual, BUT you know better, WILL use an isolating transformer and be careful with dangerous HV.
Download and read it, in your case they suggest first to measure a lot of parts, they give you a check list, replace if suspect, **separate secondary side from mains/primary side** and in your particular case: there is a starter medium power resistor (think around 2 W) which feeds the PWM controller IC straight from +300V for a few seconds until an auxiliary winding feeds it in a more efficient way.
Since it has to supply said 6 mA , or whatever starting current is needed, typical value will be around 300/0.006=50K , in fact I often see (in the book, didn´t tackle any real SMPS yet) values such as 2 x 150k resistors in parallel which means we are in the ballpark.
Obviously the 1k to 10k values you have tried so far will both burn any IC and explode themselves .... not by chance what happened so far.
Look for IC datasheet examples.
OK, I´m trying to attach the SMPS book now:
FAIL
Book size is a 15MB PDF, way too large to upload here.
Zipped it: same thing.
Split ZIP in 5 segments, named xxx.zip , xx.z01, .... xxx.z04 and Forum software does not recognize z** as valid extensions ... oh well.
If somebody can suggest some Cloud type place accessible by anybody, I´ll upload it there.
Please not Google Cloud or any one which requires you to open an account, register, give them your blood type or free access to your home banking or similar unwarranted privacy invasions.
I am actually studying SMPS, will start using them.
I´m losing lots of sales to "brick" sized Ampeg PF350/500 , Markbass and TC Electronics miniature 300/500/700W SMPS fed Class D heads so I´ll have to design my own.
I´m halfway through a *very* practical, hands-on repair manual, which now will try to post here.
Zero math, some shotgunning involved, minimal instruments, but, hey!!! , probably what "Joe PC supply repair Shop" uses on an everyday basis.
Only major point I diasagree with it is that they are somewhat kamikaze: ground scope to hot mains ground, consider an isolation transformer optional, trust home GFCI to cut power quickly before they die, claim grabbing a 310V charged main cap with both hands "may make you drop the TV or monitor you are repiring , picture tube will explode and sharp glass can cut you" but "shock is too short to kill you"
In that aspect it´s a suicide manual, BUT you know better, WILL use an isolating transformer and be careful with dangerous HV.
Download and read it, in your case they suggest first to measure a lot of parts, they give you a check list, replace if suspect, **separate secondary side from mains/primary side** and in your particular case: there is a starter medium power resistor (think around 2 W) which feeds the PWM controller IC straight from +300V for a few seconds until an auxiliary winding feeds it in a more efficient way.
Since it has to supply said 6 mA , or whatever starting current is needed, typical value will be around 300/0.006=50K , in fact I often see (in the book, didn´t tackle any real SMPS yet) values such as 2 x 150k resistors in parallel which means we are in the ballpark.
Obviously the 1k to 10k values you have tried so far will both burn any IC and explode themselves .... not by chance what happened so far.
Look for IC datasheet examples.
OK, I´m trying to attach the SMPS book now:
FAIL
Book size is a 15MB PDF, way too large to upload here.
Zipped it: same thing.
Split ZIP in 5 segments, named xxx.zip , xx.z01, .... xxx.z04 and Forum software does not recognize z** as valid extensions ... oh well.
If somebody can suggest some Cloud type place accessible by anybody, I´ll upload it there.
Please not Google Cloud or any one which requires you to open an account, register, give them your blood type or free access to your home banking or similar unwarranted privacy invasions.
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