exxos's Atari, Amiga & retro forum

@ziggy The EMI socket is interesting on these PSUs, neither of my Megas have this kind of filtered socket (Well, none of my machines has one full stop, not even my MSTE and I've never seen one at all!), but here you have one for a Mega, and exxos' PSU page shows one in a normal ST mount.

Makes me wonder if the EMI filter is older or newer? Atari were big money savers and I expect that EMI socket cost a few cents more, so did they change it later for a basic one, or add it later in order to resolve problems?

Curious :)

Look at Ebay for 2SC3459

@rubber_jonnie
I never paid attention to it.. maybe I should check al the other ST, MST, STE, MSTE, TT for these filter sockets. And you're right, Atari definitely saved every cent possible :D

@frank.lukas

I find them to be a little "expensive", with >7€ for NOS transistors :? Some newer model still in production is most likely cheaper and more efficient, or is that a wrong assumption?

Greetings

NTE2348 is a equivalent to the 2SC3459
Farnell show stock

Tom

The EMI socket is never found in an Atari for one good reason. Its not needed. Most often they are found in high end test equipment and medical equipment where measurements made are low level and increased rf interference would degrade those measurements. Putting one in an Atari is akin to putting a catalytic converter on a leaf blower. Its not going to hurt anything but its not going to provide noticable positive effects.

PaulJ wrote: 07 Jun 2020 23:13 The EMI socket is never found in an Atari for one good reason. Its not needed. Most often they are found in high end test equipment and medical equipment where measurements made are low level and increased rf interference would degrade those measurements. Putting one in an Atari is akin to putting a catalytic converter on a leaf blower. Its not going to hurt anything but its not going to provide noticable positive effects.

The only one I've ever seen is in the picture of the Mitsumi on exxos' PSU page. I've got 13 different PSUs here (I actually went off and checked) and none have it. Seems to me it's something a user may have fitted rather than something that Atari ever supplied.

Love the catalytic converter analogy @PaulJ

The closest I've seen in an Atari is the toroidal ring on the ground wire on some of the power supplies. A far cry from a EMI socket. Matter of fact the bracket on a normal ST power supply there is only room for a generic HP style power connector due to the metal bracket is flat and the board starts 1/8" after the power terminals. On a mega St bracket the power receptacle is raised so an elongated power connector would have additional room. I guess the EMI socket is for the Ataian that has everything!

Yes a review of my psu shows a basic socket. The chokes appear to be on the power supply. I guess it saved a nickle. What are radio waves anyway


Tom

PaulJ wrote: 08 Jun 2020 00:34 The closest I've seen in an Atari is the toroidal ring on the ground wire on some of the power supplies. A far cry from a EMI socket. Matter of fact the bracket on a normal ST power supply there is only room for a generic HP style power connector due to the metal bracket is flat and the board starts 1/8" after the power terminals. On a mega St bracket the power receptacle is raised so an elongated power connector would have additional room. I guess the EMI socket is for the Ataian that has everything!

Yes, I've seen that toroidal ring, and also the clip on version in a plastic shroud. I had to replace the power switch in my MSTE recently, and I can tell you it's a tight fit even with just a basic socket, let alone one of the EMI type.

Maybe @exxos fitted the EMI socket for his PSU measurements? Guess I can reinstall the old socket then and wait for my switching regulator to arrive :)