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eswets
09-07-2009, 10:07 PM
Started to assemble my dcssr from the group buy and noticed that BOM only calls for one 0.1uf cap but board has two????????. Do I need two or one and which one C1or C2?
Thanks
Eric

WWNF911
09-08-2009, 02:46 AM
Started to assemble my dcssr from the group buy and noticed that BOM only calls for one 0.1uf cap but board has two????????. Do I need two or one and which one C1or C2?
Thanks
Eric

Hey Eric,

Although I don't have a board to look at, judging from the one in the Wiki there is only one. Is your board same version or different?

WWNF911
09-08-2009, 03:02 AM
Oops double post. :oops:

eswets
09-08-2009, 08:54 AM
version 1.1 has a cap above U1 and Below U2.

WWNF911
09-08-2009, 12:19 PM
Hmmmm. It would appear that Wjohn has updated the board without also doing so on the Wiki or the BOM. I will post an update on the Group buy thread. There was an errata posted on the Wiki (at the bottom of the assembly instructions) but that was for the 1.0 version board as well.

budude
09-08-2009, 02:48 PM
Can someone describe the connections of both caps on their v1.1 boards? I am using LabRats DCSSR which was apparently based off the v1.0 layout/schematic and it only has one cap. I haven't noticed any ill affects from the the three I have built so far however. Worst case we would need to tack on a cap on the back of the board if really required.

n1ist
09-08-2009, 03:14 PM
I'd guess one between pin 1 and 2 of the regulator and one between pin 2 and 3.
/mike

LabRat
09-08-2009, 03:40 PM
I'd guess one between pin 1 and 2 of the regulator and one between pin 2 and 3.
/mike

Yeah.. that would be my guess to. The new cap would go between pin 1 and pin2 on the 7805.

mheuer
09-08-2009, 03:47 PM
I purchased from parts co-op too.

Here's a labeled picture of the bottom of a v1.1 board I got from wjohn, if that helps.

4556

I kind of want to know an answer about this too, before I plug them in.

LabRat
09-08-2009, 03:53 PM
Well the picture supports the theory that it's between the "other two pins" of the 7805. Unfortunately, from this side of the board it's hard to tell which is the input to the 7805 and which is the output.

Need to know if the "tab" of the 7805 is closest to the cap you have already installed or not. Then you can identify which is pin1 and which is pin3, to know which of the 2 caps you've already installed.

mheuer
09-08-2009, 04:57 PM
Well, I'm still a newbie, so another picture could explain it better than I could.
The flat side of the 7805 is facing the MOSFET section, if that helps.

4557

I just figured since I had a few v1.1 boards, I would post a picture.

Edit:
I don't know the answer, I just soldered the CoOp cap into C1, because thats that way it was done for the v1.0.

LabRat
09-08-2009, 05:29 PM
Well, I'm still a newbie, so another picture could explain it better than I could.
The flat side of the 7805 is facing the MOSFET section, if that helps.

4557

I just figured since I had a few v1.1 boards, I would post a picture.

Edit:
I don't know the answer, I just soldered the CoOp cap into C1, because thats that way it was done for the v1.0.

Looks to me that you have the CAP on the regulated side of the 7805 which matches the V1.0 of the board.

I haven't opened my 7805's from the co-op yet (as I had a bunch on hand previously). Am I wrong but did you have to bend the legs on the 7805 to get it into the U1 position? If yes, then I suspect it could just as easily have been placed in the U2 location without bending the legs.

I think you are safe to apply power with that one cap missing. That's how the V1.0 boards were run. It might operate more reliably with the cap there, but if you have clean power to begin with.. I suspect you will be ok.

n1ist
09-08-2009, 05:46 PM
If you look at the back side of the board in the C2 position, you see three holes. Two are connected together. C2 goes between either of those two and the other one.
/mike

mheuer
09-08-2009, 05:50 PM
Thanks for the info :).
I'm glad to see that these will work without the extra part.

As for the 7805 legs, nope, I didn't bend them.

They look bent, but that is the way the legs were configured when I got them the co-op.

That's where they fit without modification, so that's where I put them :).

eswets
09-08-2009, 11:40 PM
I tested the board last nite and it worked fine w/out the second cap. Just want to make sure before I start using them. Maybe John can shed some light on this topic if he is around.

WWNF911
09-09-2009, 04:18 AM
Well John is on Holiday but graciously responded:

"The current board is vers 1.1. The change was minor (fliped the regulator position). The datasheet suggests a min of one cap to stop the regulator oscilating under certain conditions. Being safe, you can have one either side if fitting one' I'd place it on the Output pin side I am away on vacation with limited acess so I can't update the Wiki until next week."

My thanks to Wjohn!!!

lizard050
09-22-2009, 10:51 PM
This may sound like a stupid question but.... These are powered by DC input Not ac being converted to DC. Also the Dc input power (ex 24vdc) will equal the output dc (24vdc).

I have so many different boards going that I am learning about Im starting to confuse what I read.

lizard050
10-16-2009, 10:57 PM
I've seen 2 dif pictures with the 78lo5 in either u2 or u1. The ones I have fit in u1 pos. but should the go there?