Jump to content

MB6582 J73 and documentation


Recommended Posts


Just a quick question on the documentation for the J73 bridge. In this wiki page it says it needs to be soldered for PSU options A and B:


On this other page it says that J73 is for option C only (note 3):


I guess the correct info is the one in the first page, but just wanted to make sure.

Link to comment
Share on other sites

Hi urtzurd,

Well, for options A and B J73 should be bridged to route +5V from an external PSU; and for Option C J73 is can be used to route to/from the on board +5V regulator. So for all options the J73 footprint is used, just in very different ways depending on how you plan to supply power. I think that on the parts list, it is saying that the use of a header is mainly needed for option C, as A and B only needs a wire bridge. Of course one could use a header and a shunt for A and B, OR not use a header for C and solder jumper wire directly to the solder pads.

There are so many options to supply the board that it can be confusing but with a little study of the schema and reading the forums it will make some sense.


Link to comment
Share on other sites

Looking over the documentation, I'm convinced that J73 is basically vestigial, left over from when the design of the MB-6582 was mostly hypothetical. Wilba seems to have really tried to make the power section as versatile as possible, to allow for a number of different power configurations, but in the decade since the design was released, most folks seem to have opted almost exclusively for one of about three common options.

The only scenario in which you don't need J73 is one where you're using a PSU that supplies separate voltage rails right out of the box, *and* you're not using the on-board switch. In this scenario, you'd just connect all respective supplies to J4, which is a direct connection to the different rails and bypasses the entire power circuit and switch. Even in this scenario, bridging J73 is unlikely to make any difference, as it will only connect a couple smoothing caps to the 5V line (if they're even stuffed). Those extra caps may be beneficial (smoothing out the 5V rail somewhat) or they may cause problems (if your 5V supply comes from a switcher that doesn't like excess capacitance), but no matter what, it's quick and easy to get working.

Basically, unless you're doing something funky in your power section, just put J73 in.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...