no voltage on output of capacitor

[Big Red]

well I'm still trying to get my easyvibe working so I made a new pcb and rebuilt it. to my dismay it still didnt work. so this evening I got out the dmm and started tracing. the first cap on the +9V is getting voltage but the negative side is showing 0v. I used a sharp point to scrape all around the pad to make sure there is no short.
now I'm stumped. does this sound like a bad cap or could something after this cap be shorted and causing this? (I've scraped all instances that look like they may be shorts)

[Papa_lazerous]

Ok I havent seen a schematic and dont know what cap you are referring to but....

Amongst other reasons for using a cap one main reason would be to isolate the DC voltage.  like when you bias a transistor you'd use caps to let the signal through as its AC but the DC voltage wont pass through.  So putting the DMM across it may not actually measure anything as its not meant to pass DC.

I dont know if I have explained that too well but hopefully someone will fill in if I havent said everything quite right.  Hopefully you get my point.

[petemoore]

the first cap on the +9V is getting voltage but the negative side is showing 0v.
 Could be we're talking about a DC filter cap intended to be connected between V+ and V-, correctly connected: V- = 0v?
 Without the schematic I think it's a fairly good guess.
 

[Big Red]

ah yes, you guys are right. thank you.
back at square one I suppose

[Papa_lazerous]

ok square one it is, mabe a link to the schematic and some clues as to whats happening or not happening and someone can help

[R.G.]

The schematic is here:
http://www.hollis.co.uk/john/easyvibe.jpg

Did you use this PCB layout?
http://geofex.com/PCB_layouts/Layouts/easyvibe.pdf

The real answer is to go read the sticky thread at the top of the forum entitled "Debugging: What to do when it doesn't work" and follow those directions. This procedure almost always fixed new but dead pedals.

[axeman010]

Hi

Be aware that if you are using the layout that R.G. showed above there is a short in the tracks that should not be there.

I feel sure that somebody has already posted a diagram on the forum with this high lighted !

Good Luck !

Axeman.

[R.G.]

Be aware that if you are using the layout that R.G. showed above there is a short in the tracks that should not be there.

Can you point that out for me? I'll correct it ... if I haven't already.

[Big Red]

yes its the version from Geofex.com
I know all about that trace. I've read all I could in the archives (aka used the search button) before I took on this project.
I'm just waiting on a fresh battery and I'll post voltages in the propper format. I just had a eureka moment last night when I seen that 0v and wanted a professional opinion 

[rockgardenlove]

This is just something that popped into my head...
Maybe RG fixed it already, and the trace should be there?  Some of the posts on this forum are REALLY old, and RG may have fixed it a while ago.

[axeman010]

Hi R.G.

Can you point that out for me? I'll correct it ... if I haven't already.

I hope I'm right about this but when I made the Easy Vibe a few weeks ago there was a link on the board
between R18 and the -ve pin of C9 - of course I could have just made the board badly, but I am sure I found
this somewhere else on the forum too.

Sorry could not work out how to copy the layout and mark the problem and post it back 

Regards

Axeman.

[Big Red]

This is just something that popped into my head...
Maybe RG fixed it already, and the trace should be there?  Some of the posts on this forum are REALLY old, and RG may have fixed it a while ago.

I dont think thats the case

R.G. I believe this is the trace in question

[R.G.]

That's probably it. However it's not shorted on my artwork if you'll look closely at the PDF. I think that the printers just can't handle it.

I'll see if I can open that up a bit. 

[axeman010]

Hi  R.G.

Many thanks !!!!!

Axeman.

[TELEFUNKON]

that distance between the eyelet of R18 and the horizontal trace
which becomes viewable with PDF zoomed to >200%
is really close enough for a cigar.

[R.G.]

Well, I never claimed that my work was perfect - 

I'll see if I can find the layout files and update it. 

[R.G.]

Found it. It's updated now.

I had to get it from an old CD backup. I'd forgotten that it was five years ago that I did that.

I found why that area is touchy as well. The original PCB file has plenty of clearance. I had to make that PDF by printing the layout to a file on a postscript printer driver, then import the postscript into a corel draw drawing, add the explanatory material, then export it to PDF. One or more of the conversions along the way fattened up the black areas a bit. There's still a clearance, but it's not much and any tolerance from printing or spreading of toner under heat can make a short.

Have fun with it.