Stern PS-1000 bridge diodes upgrade

joeycuda

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I'm upgrading a clean, unmodified Stern PS-1000 board for my Berzerk restoration. I'd like to use this instead of a switcher, although I know some say this board is crap.

I've already replaced the 3 larger filter caps and plan to replace the headers and smaller caps.

The +5 bridge consists of three "8038" (CR1,CR2,CR4) and one "8041" (CR3) diodes.

It's the only part of the PCB that has some discoloration from heat, so what would be the "upgrade" diode for this and I can mount them a little farther from the board.

Thanks in advance.
 
Those numbers you give are the date code of when the diodes were manufactured. The schematic says diodes CR1 through CR4 are type MR500.

You can upgrade to type 1N5402 or 1N5404. These can be bought at Radio Shack as part # 276-1143 and 276-1144 respectively.
 
Oh crap. Well, I learned something. I do see MR 500, but I wasn't familiar with that type.

Thanks for the advice!
 
In general, replacing the diodes won't help them run cooler though. Something needs to dissipate the heat. You could mount them farther from the board, but the heat will still travel down the legs, and that may actually cause the diodes to burn up (because they'll run hotter, since currently the large copper traces are acting as a heat sink). You could add an external heat sink, but that's probably overkill.

The discoloration is really no problem... it's just from years of hot diodes running all day every day... you're not going to get rid of the discoloration, and odds are that in a home use environment, you're not going to add much to the discoloration.

I personally don't think those power supplies are bad... they have a very simple design, and once you resolder all the headers, they're fine (though I've never seen one that didn't need its headers resoldered ;) ). I'd never replace one with a switcher.

DogP
 
In general, replacing the diodes won't help them run cooler though. Something needs to dissipate the heat. You could mount them farther from the board, but the heat will still travel down the legs, and that may actually cause the diodes to burn up (because they'll run hotter, since currently the large copper traces are acting as a heat sink). You could add an external heat sink, but that's probably overkill.

The discoloration is really no problem... it's just from years of hot diodes running all day every day... you're not going to get rid of the discoloration, and odds are that in a home use environment, you're not going to add much to the discoloration.

I personally don't think those power supplies are bad... they have a very simple design, and once you resolder all the headers, they're fine (though I've never seen one that didn't need its headers resoldered ;) ). I'd never replace one with a switcher.

DogP

Well thanks.. I kinda thought, if upgrade diodes were a couple of bucks, why not. I may just leave them alone, and yes, my stuff never stays on for more than a few hours every once in a while. I will be replacing all of the headers with new and repinning the connectors with trifurcon pins.
 
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