First madbean build- lowrider- problems

[claytushaywood]

So I just finished up the low rider build.  had a few problems with the board creating traces between two components, or maybe it was me revealing a trace that was already there.  anyway, I had components making contact, but the schematic showed they were supposed to make contact so that was okay.  does anyone know what i'm talking about here?  i got like a little silver trace in between two resistors in places I had to desolder components.

here's the real problem... this is my first build with PCB mounted pots.  I got the short ones from mammoth and as I began to mount them on the board- they are showed on the drilling template that they need to be mounted back over the top of the board.  i took this to mean the pots on top of the component side of the board.  this did not work well at all!  there's a big 14 pin chip with a socket right below one of the pots, and even the trim pot forced me to lean the pot forward.  so now all the pots are leaning forward and the board definitely wont fit into a 1590bb.

Can i install the pots so they're hovering over the trace side of the board?  How am I supposed to know in the future?  there's no numbering on this build pdf or anything!  I'd really appreciate some insight on this

[Om_Audio]

Hey there- sorry you are having troubles- I'm sure the folks here can help you sort them out.
If you could link some pics that would be helpful. You can post them on Flickr or Picasaweb (google) and insert the links or just link to the external pics (easier but pics wont show here in the post)
C

[Loztboy]

The pots are supposed to be mounted on the solder side of the board. The pot holes are labeled in the doc.

[claytushaywood]

The pots are supposed to be mounted on the solder side of the board. The pot holes are labeled in the doc.

thanks man!  I woulda never saw those tiny little numbers there

[madbean]

claytushaywood ,

I'm sorry that you've had a frustrating time with the build. For future reference: all the MBP projects that allow for PCB mounted pots are fitted underneath the PCB. I could have more explicitly stated this in the document, but I relied on the pot numbers on the silkscreen in this case. I will try to remember to state that more clearly in future documents.

I'm a little unclear as to what you are describing in the first paragraph as far as the "board creating traces between two components". Can you clarify that a bit more?

[nzCdog]

Check out this cool idea for using normal pots in a board mounted style... props to Lacesensor
http://www.madbeanpedals.com/forum/index.php?topic=3222.0

[claytushaywood]

thanks for the help guys... that tutorial is actually what i was gonna do with the .50 cent tayda pots originally, then i was thinking about sanding down the pins to fit into the holes on teh pcb.

now, i started trying to desolder the pots from this board, and for the life of my i cannot get all of the solder out.  I absolutely cannot get them out, i already broke one pot in the process of it, i've had problems desoldering anything on this board really though.  i'm in fear of losing my whole board.  I might have to cut off the pots and try to jerry rig the other ones through... if only i had 4 right hands and 3 soldering irons

anyone got any tips on how to do this without ruining the board.  i am really fearing im screwed at this point, never had this much trouble desoldering

[nzCdog]

You need a desolder pump or solder sucker... heat the join then suck it out.  Be careful with the board, the right tools and patience will mean you can desolder a number of times no problem... good luck
here's a video demo
http://www.youtube.com/watch?v=Aw4lZGk90i4

[lloyd17]

I find it easier to cut off the pins before removing pots. rather lose a couple bucks in parts than the whole board. plus the pots can be used again lug style.

[claytushaywood]

oh i have a solder sucker which i use most of the time without a problem, i busted out the desoldering braid and desoldering iron with pump for this with no avail!

[nzCdog]

Oh bummer, I hate those tricky spots....  
Sometimes if you reflow the joint with solder and start again it can come loose.  Also you can try using a toothpick to poke out any fragments in there while the joint is heated by your iron. Even if you tear up a pad you can save the pcb, don't give up.

Good luck

[claytushaywood]

I find it easier to cut off the pins before removing pots. rather lose a couple bucks in parts than the whole board. plus the pots can be used again lug style.

do you cut off the tabs from the bottom and top?  i was thinking i could do that then maybe somehow poke something through the holes while applying heat to clear them out.  could you explain a little more, tricks are definitely welcome, id hate to lose such a large board

[claytushaywood]

Oh bummer, I hate those tricky spots....  
Sometimes if you reflow the joint with solder and start again it can come loose.  Also you can try using a toothpick to poke out any fragments in there while the joint is heated by your iron. Even if you tear up a pad you can save the pcb, don't give up.

Good luck

nice! reflowing solder seriously crossed my mind 5 minutes before i read this, must have caught it in the universal subconciousness.  those are exactly the kinda tips im looking for. 

i was thinking that it has been more difficult to resolder lately, not just on this board now that i think about it.  ive been using a hotter setting on my iron and a lot less time heating the joint.  i also switched from plain 60/40 to solder with silver content.  which has been great for drying quicker and the higher heat has really kept my component heating to a minimum (i also use a heatsink clip where possible) but i have been putting transistors in without sockets where i want to and not using sockets on diodes or chips with 100% success, until it comes time to desolder a wrong component.  could this be causing my difficulty?  or is it the double sided pcb?

[lloyd17]

I have trouble getting components out of double sided boards with any solder type lol. RE the pot legs I'd just cut t hem at the angle leaving enough to grab the pin with hemostats (my tool of choice for these tasks) and enough terminal on the pot for later recycling. I never try to remove solder until after the component leg is out. Actually I add solder when pulling components to ensure the whole joint gets gooey, then remove the lead, then clean up the hole.

[madbean]

How to remove the pots without breaking anything or even using a desolder braid: Secure the PCB so that it does not move when gently tugging the pots. Melt the solder on the right pin while very gently pulling the pot away. Quickly repeat with the middle then the left pin. If you do this gently the pot will start to pull away from the PCB without damaging it in any way. Just keep melting each pin for one or two seconds and then gently pull. Eventually the pot will come out. Don't force it or you may damage the actual pad. If any solder is left in the pad after removal, use a combination of solder sucker and poking the tip of your iron through it to remove it.

I do this all the time when my actual desolder pump won't fit in a tight space.