Friedel Bruening: > There must be at least one feet back, normally there are 2. The > first will be the current measurment of the switching transistor, > the second mostley comes from the secondary side, which is > got to be isolated, the use opto's most of the time.
It doesn't have to be isolated and a low voltage DC/DC switcher probably won't be. If the primary is at mains voltages you usually need to do so for obvious reasons. > Have you verified the switching cap to have low ESR ? > I had experience with faulty switching transistors, which > looked just fine to simple checks, but just did'nt work > in this PWS anymore. I've repaired a few SMPSs (and designed a few). Top of the list of failures I've seen are capacitors. Either the ouput voltage smoothing ones or ones which stablised the voltage supply to the controller on the primary side. Next on the list is shorted switching transistors or ones that have otherwise failed. I've also seen a couple of unstable control ICs (they shows signs of working but weren't 100% right) where the PSU worked once they were replaced. The inductors normally survive but I've never dealt with one like yours. RP -- Author: Richard Purdie INET: [EMAIL PROTECTED] Fat City Hosting, San Diego, California -- http://www.fatcity.com --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB CHIPDIR-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
