I have a bad chip here, on a plug in switching walwart supply. the chip is bad, an 8 pin dip pwm chip. the chip munber is sd4844p. I have not found a source for the buyers to get one here. I found another small switcher with an 8 pin dip, number VIPer12. the chips are almost identical, with the same ratings and such, but with the supply and feedback pins reversed. why do mfgrs have to do that? especially when they dont have distributors around the world.
cliff

 

It is an absolute requirement of low cost commodity product manufacturing. Making it easy for you to repair makes it easy for competitors to make a copy and undercut your price. The economical thing for you to do is to buy another whole unit instead of wasting your time trying to acquire a replacement part and repairing the failed unit. Get over it and move on.

 

because some things are a bit more specialized, and are not available at walmart. its bad enough that the mfgrs will not usually supply any repair info, but for a parts mfgr to not have a distribution network is irresponsable.

 

No, it's just good business. If their business model is never to sell to anyone but large volume OEM's, they don't need the cost or hassle of distys. In the 80's and 90's, many chip companies making parts for PC graphics boards, disk drives, and sound cards had no manufacturing or distribution. If you didn't want 100,000 pieces, they wouldn't even take your call. If you did, parts were drop shipped from their outsourced foundry direct to you.

ak

 

I found your chips on ebay and Digi-key

http://www.ebay.com/itm/SD4844P-Original-New-Silan-Integrated-Circuit-/121107160055

VIPer12 is available from Digi-Key

 

No chip manufacturer is going to stay in business selling parts in single quantities. A full reel is typically the min buy. If you need less than a full reel you are looking for a distributor, and you are paying a premium for that service.

On a B2B basic a manufacturer will typically sample several parts for free, but there can be a gap between that and a full reel when one needs to make a prototype run. I had a problem with Maxim a few years back for a device not in distribution: awesome 30MHz op amp no one carried and I needed a few hundred. Eventually they did sell us the partial reel but they were not happy to do so.

 

digikey dosnt have the sd4844. I already searched and found the viper12 at a few aproved vendors. I only found the sd4844 at asian dealers not on the aproved vender list.

 

digikey dosnt have the sd4844. I already searched and found the viper12 at a few aproved vendors. I only found the sd4844 at asian dealers not on the aproved vender list.

If it was me, I would buy two of the viper12s, then install the chip with the two power pins either bent up or straight out (not into the board), then wire short pieces of 28 gauge hookup wire and cross connect to the holes on the board (assuming it was mounted on a circuit board) reconnecting the power and ground. Should work. The purchase of the second chip is because if you have a spare, you will never need it, and it doesn't cost any more to ship two than it does for one. That is how it works for me. Joe