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Posted

im asking because i have some troubles with my core and i'm trying to replace every part before it is fixed. i have at the moment a 7805 2A. those 2A make me suspicious because when i searched the forum, a 1A was recommended.

however - with my old core i had alot of problems with a 1A 7805 when i had made a full blown midibox with 64 pots and 32 leds - it was resetting itself all over the place - changing the 7805 to a 1,5A one did the job and works perfectly until now.

the problem with the new core is that the ground seems totally insufficient - even when i ground all analog ports directly on the core i get a lot of feedback from them.

Posted

im asking because i have some troubles with my core and i'm trying to replace every part before it is fixed. i have at the moment a 7805 2A. those 2A make me suspicious because when i searched the forum, a 1A was recommended.

1A is the standard, but 2A should be fine, provided you're not trying to sink too much current with your LEDs/LCD/etc, in which case you're gonna hurt the chips

however - with my old core i had alot of problems with a 1A 7805 when i had made a full blown midibox with 64 pots and 32 leds - it was resetting itself all over the place - changing the 7805 to a 1,5A one did the job and works perfectly until now.

Yeh that was because the LEDs were using up all the juice. (but apparently not too much for the SR's)

the problem with the new core is that the ground seems totally insufficient - even when i ground all analog ports directly on the core i get a lot of feedback from them.

that shouldn't happen, sounds like you might have a data line somewhere shorted with the ground plane. This could be bad for the chips too, I'd pull all the ICs from their sockets, disconnect power, grab the meter, clamp one probe to a ground pin, and do a continuity test on all the data pins. Sounds like a lot but it'll only take a minute. Just drag the probe around until you hear the beep ;)

Posted

Well that's just a maximum tolerance... it means that any current draught up to 2A will be OK, but more than that will overload it. So long as you don't overload it you'll be fine.. . but if you're overloading it then you've got other issues, because you'll certainly be overloading a 1A max vreg ;)

I can tell you one thing you're doing wrong - you're trying to make everything work all at once. Take it back to just the core, then add LCD, then dinx4 one at a time, then doutx4 one at a time, etc, testing all the way... Make sure everything works before advancing..that way, when it stops working, you'll only have changed one thing, so you'll know that one thing is the cause of the breakdown :)

Posted

yeah you're right about this one - but it seemed fine all the way through so i didn't bother checking anything. the problems started after i tried to launch the sid where i realised that actually a few things aren' ok.

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