First madbean build- lowrider- problems

[claytushaywood]

I just did a combo of all the stuff listed and actually didnt see madbeans last post until just now.  wish i woulda thought about leaving solder in there so I wouldnt have ruined so many pads.  i only had to cut off one pot though.

but it looks like I lost some pads, which ive never dealt with on a double sided board.  i usually just follow the trace and it's super easy, i was using guitar pcb boards so i havent had to deal with this for a while.

how do i go about fixing this?  I lost the following pads

component side- upoc1 #2 maybe doct 2 #1
trace side- Doct2 #3 up oct #1 & 2

and maybe a few others, that are still partially connected but look like they could still make contact if pushed down and soldered in.  major bummer, am I gonna have to solder wires to where they go to components on the board?

[claytushaywood]

okay, i dont really need it all spelled out completely.  here's a couple concise quesitons.

if the pad is okay on the top and gone on the bottom (trace side of the board) or vice versa, do I need to jumper it to where it's supposed to go?  Cuz if one of the sides will work I'll only maybe have to do Uoct1's 2nd terminal to R49 which is right next to it.

if i do need to hardwire all these bad pads, i know where they need to go for the most part.  only question is on Doct2 terminal 3 makes a connection with VR+ can I just tap that from anywhere on the board or should I make a jumper to the 9v pad on the board?

regarding the two pads in the 9V solder pads on the upper right corner of the board.  is the square pad V+ and the circle pad ground?

[nzCdog]

Good that you got them off...  Bummer that it ruined some pads.

if the pad is okay on the top and gone on the bottom (trace side of the board) or vice versa, do I need to jumper it to where it's supposed to go?  Cuz if one of the sides will work I'll only maybe have to do Uoct1's 2nd terminal to R49 which is right next to it.

If you make a good solder connection, it should make continuity between the top and bottom if the pads aren't completely removed

if i do need to hardwire all these bad pads, i know where they need to go for the most part.  only question is on Doct2 terminal 3 makes a connection with VR+ can I just tap that from anywhere on the board or should I make a jumper to the 9v pad on the board?

VR will be different from 9V.   If you have a DMM (Digital Multi Meter) you can check continuity to determine where intervention will be needed...  You may consider wiring the pots to the board rather than soldering directly, which will give you the option of connecting to equivalent points other than the busted pads...

regarding the two pads in the 9V solder pads on the upper right corner of the board.  is the square pad V+ and the circle pad ground?

From memory the Square one is 9V... not sure about the circle...

Good luck

[claytushaywood]

so... I'm not understanding your answer if the pad is missing on one side completely, the other side wont make a connection to where it is supposed to go?

i guess i dont really understand how double sided pcb's work.  it looks as though the pots are only connected to individual traces

-Where is VR then?  i'm a noob.

also is there a chance these pots are ruined due to a little bit of excessive bending? everything is still connected and whatnot.

[nzCdog]

so... I'm not understanding your answer if the pad is missing on one side completely, the other side wont make a connection to where it is supposed to go?
i guess i dont really understand how double sided pcb's work.  it looks as though the pots are only connected to individual traces

The dual layer pcb pad-holes have 3 sides; top, inside and bottom.  There may be enough conductive matter left in the pad hole still to complete the connection if a good enough solder joint is made.

-Where is VR then?  i'm a noob.

VR is a voltage reference in the schematic.  Just like all the GNDs (ground)are connected, all the VRs are connected too.  However VR is not neccesarily the same as 9V.

also is there a chance these pots are ruined due to a little bit of excessive bending? everything is still connected and whatnot.

Yes, you can test it with a DMM, using the Ohms/resistance measuring function.  Measure lug 1 and 2 whilst turning the pot a full rotation. The readings should change relative to the turn of the pot from '0' the maximum value of the pot (in this case 100k)... do the same with lugs 2 and 3...

[claytushaywood]

i'm still  a little confused on how I tap a VR if the pad is missing. 

I see all the VR points on the schematic, but I'm not really sure how I would go about tapping into it for the broken solder pads.

Could I for example: Lug 1 of the Clean pot is connected to VR- Can I just wire my missing solder pad of Lug 1 of Up Oct 1 to lug 1 of clean pot?  that's all i'm trying to figure out... but it seems like that would also be connecting the two lugs together, but i guess they are pretty much connected... correct?

If the bottom pad is completely gone, do you think i should just try to solder the pots in normally (correctly) and make a good connection or do you think i should just go ahead and tap the points where they are connecting.

I understand the basic concept of a double sided pcb.  but i'm curious as to the purpose of the 3 solder pads, when the schematic appears to show that each point i'm looking at is only connected to one other point.  i thought it was more for arranging components in paralell and points with multiple connections more easily on a pcb.

Sorry this thread has become so long!  I really appreciate all the help guys!

[nzCdog]

Could I for example: Lug 1 of the Clean pot is connected to VR- Can I just wire my missing solder pad of Lug 1 of Up Oct 1 to lug 1 of clean pot?  that's all i'm trying to figure out... but it seems like that would also be connecting the two lugs together, but i guess they are pretty much connected... correct?

Yes that will work, you could just run a wire between the two pots

If the bottom pad is completely gone, do you think i should just try to solder the pots in normally (correctly) and make a good connection or do you think i should just go ahead and tap the points where they are connecting.

You'll have to decide that... but I would try the pots in the correct spot first... My preference is to use wire and make a really good connection... get it hot, and load that sucker with all the solder it can eat, whilst keeping the wire and board completely still.  A good joint will protrude healthily both sides of the board (without becoming a big mess)  Do that, and hopefully the connection will 'self repair' and work out fine. 

If that fails, run a wire from the pot to the next component down from the busted lug, and share that hole with the other component.  (Meaning more careful desoldering first)

I understand the basic concept of a double sided pcb.  but i'm curious as to the purpose of the 3 solder pads, when the schematic appears to show that each point i'm looking at is only connected to one other point.  i thought it was more for arranging components in paralell and points with multiple connections more easily on a pcb.

Depending what the pot is used for, it can sometimes use either 2 or 3 lugs.  When designing the pcb for board mounted you have all 3 for rigidity in assembly, there are other reasons also but all the madbean pcbs have all 3 pads per pot, even the non mounted or single sided designs.  I don't really know if that answered your question or not... lol

Sorry this thread has become so long!  I really appreciate all the help guys!

Your welcome

[claytushaywood]

I understand the basic concept of a double sided pcb.  but i'm curious as to the purpose of the 3 solder pads, when the schematic appears to show that each point i'm looking at is only connected to one other point.  i thought it was more for arranging components in paralell and points with multiple connections more easily on a pcb.

Depending what the pot is used for, it can sometimes use either 2 or 3 lugs.  When designing the pcb for board mounted you have all 3 for rigidity in assembly, there are other reasons also but all the madbean pcbs have all 3 pads per pot, even the non mounted or single sided designs.  I don't really know if that answered your question or not... lol


Here, I'm not talking about the 3 lugs on the pot... I'm talking about the apparent 3 pads you mentioned inside of each individual pad of the double sided pcb.  I'm saying- I thought a double sided pcb would allow for multiple connections to made, like parallel components or something.  but on this schematic it seems that my broken solder pads are only connected to one other place.  Why would I need all of the solder pads (as in the top and bottom and apparent pad inside the board) to connect?

again, not talking about lugs 1,2,3 of a potentiometer---solder pads individually

[madbean]

Let me see if I can clarify: each pad you see on the PCB is a singular pad. It connects to either components on the top side of the board or bottom side through traces. The traces on the top and bottom usually go to different places, so a top trace may connect the pad to one end of a resistor (via another pad), and the bottom may connect to a capacitor somewhere else. The pads themselves are "plated though". This means whenever you solder an actual lead or wire to the pad, it makes all the connections at once because the top and bottom portion of each pad is connected via s small amount of plating in each pad hole.

So, if you rip up or melt off a pad on the top, for instance, you may lose the connection to whichever component the top trace routes to. But, the bottom connection should be okay, because assuming the pad is intact on the bottom, the trace attached to it is also still in place.

However, it's much simpler than that. Whenever you lift a pad, top or bottom, all that is required is to figure out what trace that pad connected to, and then use a wire to jumper from the lead on the lifted pad to the "end of the line".

Here's a pictorial example from the LaVache. The green area I've highlighted is where we are going to make the example.  The pad that the end of D2 goes in is routed on both the top and bottom to different places. On the top (red) it goes to D1 and C3. On the bottom (grey) it goes to the middle pad for the Shape switch.

If you lifted the pad on the top, then you would run a wire (on the bottom of the board) from that D2 pad to where the top trace connects to D1 or C3 (meaning their pads). If you lifted the bottom instead, then you would connect the wire from the lead of D2 on the bottom to the middle pad on the Shape switch. If you managed to lift top and bottom, you would need to run wires to BOTH places (always do it on the bottom of the PCB--it's easier).

Hopefully, that makes it clear. BTW: the large grey areas on the bottom are all part of the ground plance. The connect to grounded pads via little tiny slivers of traces (called Thermals) which you can just make out in the pic.

Let me know if there is still any confusion

[madbean]

I just noticed the LR doc doesn't have a pic of the trace layouts. I've been including these more recently. Here it is...will probably help you a lot!

[claytushaywood]

Ballin!  I get it!  I get it!  You guys are amazing people!  I have been inspired to help when I can. I hope one day I can be of 1/100 as helpful as the people on this forum!  Thanks!