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this is gonna be the dumbest...
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this is gonna be the dumbest...

by Must!Delicious on Tue Jun 07, 2005 4:29 pm

okay, so i am almost finished with with the ps and voltages are weird. this is okay-not freaking out yet. the problem is that i think it is a result of a screw up in step one or two. now, in step one it says to do this:

Test that the votage across the jack terminals is 12VAC or so.

so, i realize that votage = voltage, but the first paragraph, which explains how the voltage comes in 9vac and is doubled to 18 and then split up makes sense. i don't understand why or how the jack terminals would be showing 12vac. more importantly, if that is not a typo, then i need help making sure i am testing the right points, and setting the right settings on the multimeter, and so forth, because i am getting 9.3-9.9 - which makes sense, but not according to the manual.

also, if i ignore that and move on...
things seem okay until step 6:
The voltage at pin #1 of J4 should be 5.333V.

my problem here is that when i turn the pot up to increase the voltage it maxes out below 5v. somewehere in the high four range i think.

thanks all.
m!d
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by altitude on Tue Jun 07, 2005 4:57 pm

edit: I need to read the whole post
Last edited by altitude on Tue Jun 07, 2005 5:02 pm, edited 1 time in total.

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Re: this is gonna be the dumbest...

by adafruit on Tue Jun 07, 2005 5:01 pm

Must!Delicious wrote:Test that the votage across the jack terminals is 12VAC or so.

so, i realize that votage = voltage, but the first paragraph, which explains how the voltage comes in 9vac and is doubled to 18 and then split up makes sense. i don't understand why or how the jack terminals would be showing 12vac. more importantly, if that is not a typo, then i need help making sure i am testing the right points, and setting the right settings on the multimeter, and so forth, because i am getting 9.3-9.9 - which makes sense, but not according to the manual.


voltage = voltage, but specification != voltage. a "9VAC" wall plug is rated for 9VAC at maximum load. which means it can be as high as 15VAC when not powering anything.

also, if i ignore that and move on...
things seem okay until step 6:
The voltage at pin #1 of J4 should be 5.333V.

my problem here is that when i turn the pot up to increase the voltage it maxes out below 5v. somewehere in the high four range i think.


check your parts, particularly the 1% resistors

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by Must!Delicious on Tue Jun 07, 2005 5:07 pm

i am reading 9v and change instead of 12 or there abouts at the jack - is this bad?

also, thanks...i had r4 and r5 mixed up.
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by adafruit on Wed Jun 08, 2005 12:39 am

yeah. you probably put one of your capacitors in backwards

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by Guest on Wed Jun 08, 2005 4:30 am

actually, i know i sound like an ass, but i am just bad with the written notes here....my caps were put in fine. just like the picutres with positives where they belong. so as i said, all other voltages okay, as the manual says, its just the first step that's got me a little nervous.

the resistors that i flipped, those were corrected and 5.33 reads perfect (i'm so dumb dumb), but seriously, if the caps are right and its still reading low, is it possible one was fried or bad, or should i continue and as i mentioned earlier, should i try re-reading this a different way. the pic was hard for me to see in that step and maybe the reading i got sucked or maybe i have no idea how to get things right on my radio shack meter....

forgive my poor skills as my only experience is with vector graphics arcade games with bad monitors.
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step one caps for the ps

by Guest on Wed Jun 08, 2005 4:39 am

btw, i'm getting around 13v on c5 and c3. is this fine?
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by adafruit on Wed Jun 08, 2005 12:21 pm

i think something is shorted or put in wrong, as that would cause the voltage at the jack to dip so low. in theory...if it works and you get the right 5.333V, 6V, 12V power then theres no reason to not keep going.

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See for yourself!

by Jonnay on Wed Jun 08, 2005 12:42 pm

Check the pictures at http://www.ladyada.net/make/x0xb0x/fab/ps/index.html

In short... Yes. 13 V at C3 and C5 are fine.
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Please be positive and constructive with your questions and comments.