You need to install two 4700uf 65v capacitors, connected in parallel, from the +12v terminal to the common terminal. You can get these from Radio Shack. Make sure you get the polarity correct or the capacitors will very likely explode.
After rereading your post this may not be your problem. Sometimes a PS will shut off when you first try to power up the charger. The above solution should solve that problem. You may be exceeding the amp limit of your PS. Some PSs don't have much capacity on the 12v side. When selecting a PS for this application read the label on the PS and pick one with the highest +12v amperage rating that you can find. The ones I use typically have a 12A - 15A rating. A lot of the ones I've seen have an 8A rating. Not saying that it won't work, but personally I wouldn't use it for this application.
Last edited by calvin; 06-01-2003 at 10:59 PM.