I'm repairing a dead philips VR 600, the SB340 diode on one PSU output gave s/c both directions, I don't have one in my spares box...anyone know of a suitable equivalent?
datasheet:
cheers, B
I googled "3A 40V shottky barrier" and got several results on the first page.
It's a very common problem on Philips PSU's. Replacement type is not critical. Just about anything of similar rating, intended as a smps secondary reccy, will work perfectly well in my experience.
Arfa
just tried a BY255, but got erratic operation and overheating - probably couldn't handle the frequencies of the SMPS..... today I bought an exact replacement schottky so will post back when installed. Ben
??????????????? I guess I wasn't clear enough when I said
"intended as a smps secondary reccy".
The *exact* type is, as I said, not critical. The *generic* type of course
*is*. A secondary-side reccy in a smps *must* be a high speed job, typically a Schottky type, as you were originally asking about. Sorry if I implied otherwise ... :-)Arfa
Very occasionally some manufacturers get it wrong with SB rectifiers, its sometimes helpful to check the peak reverse voltage using a simple peak detector consisting of nothing more than a rectifier and capacitor in series directly across the rectifier under test, the measured peak voltage must be added to the rectified voltage - the sum of which must be less than the SB rectifier's rated voltage.
If the voltage is excessive check the primary snubber first, if that's OK then the manufacturer has got it wrong - the options are fit an SB rectifier with sufficient voltage rating or add a shunt resistor to the capacitor in the peak detector and leave it in place as an individual snubber just for that rectifier.
Sometimes manufacturers are not too sure of their own design, one Philips DVD I worked on had holes and screen print for either the 3A leaded package or a TO220 type. The 3A type had failed so I made use of the TO220 position with a 6A rectifier - the repair didn't bounce.
On Tue, 30 Sep 2008 12:47:27 -0700 (PDT), b put finger to keyboard and composed:
What about a 1N5822?
- Franc Zabkar
-- Please remove one \'i\' from my address when replying by email.
no worries Arfa, my misunderstanding. Anyway I fitted an SB 560 and all seems well. thanks for all the responses! B.
Glad you got it going. There's usually no other issues with that failure mode in those machines. Just the diode, and that's it.
Arfa
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