Hello , this is my first time using Fritzing and i like the simplicity of it. However i am wondering what i am doing wrong.
I made a schematic then went to PCB view. I moved the pieces around and did all my single sided routing. Now when i go back to the schematic it is a complete mess ! components all over the place traces missing. now here is the frustrating thing. if i fix the schematic the PCB is now got missing traces!
Is there a setting to uncouple the schematic and PCB?
It has been 30 years since i have done any PCB design and am well out of practice, but i had a nice schematic and then a nice PCB but it looks like i cant have both…please help.
Basically you only work in one view, ie SCH, and then trust it in the others. FZ doesn’t really work in two directions like it should. You must have changed components in the PCB, which will muckup the SCH, or didn’t trust the ratsnests from the SCH and made the traces different in the PCB.
From experience of helping others, at this stage it would probably need an expert to fix the original. I would start again with a new one using the original next to it to copy.
If you want to upload the orig here using the 7th button, I can have a look at it.
thats ok. i made a copy of the project and will fix the schematic in that one. save it as a pdf. if i can…
then just leave the original as the PCB.
seems very stupid to alter the schematic because the parts on a PCB are moved around. this is a simple LM386 amplifer module with around 10 components. glad i found out the limitations before i tried a larger project.
BTW ther is something wrong with the LM386 that comes in the default components. On the schematic the "wires"wont connect correctly to pins 2 or 7.the wire seems to connect 1 grid above the pin 2 location and on pin 7 which is at the bottom of the graphic the "wire"connects half way up. looks bad . might need another program to do the schematics and just do the PCB on fritz…
It shouldn’t alter the SCH if you only moved parts around in PCB, that’s why I suspect you changed something in PCB like picked a different part with the Inspector - parts are 3 view groups, so you can’t just change a PCB footprint without affecting SCH because it’s a new part -, added a part - it’s a mightmare if you don’t add it to SCH first -, deleted a ratsnest, or something like that.
I can’t see much wrong with pin2 but pin 7 connects halfway in SCH.
LM386 amp small.fzz (13.8 KB)
i bet thats what i did. i removed a ratsnest when it refused to connect correctly…
any way here is the project
The PCB looks nice. It’s not essential for this case but everyone has switched from 90º corners to 45º corners because it causes problems in high frequency circuits.
Wow that SCH is a bit of a mess. If you look at some of the solid traces they have ratsnests bypassing them, and if you look at the components they have red pins so they aren’t actually connected. One trick is to make sure all the connections are green, and that if you move parts around the traces stay connected. Like you could have a 4 wire junction where trace 1 is connected to 2, and a 2nd junction sitting on top where 3 is connected to 4. All pins will show green, but 1,2 isn’t connected to 3,4.
The usual way is do the SCH first, and make sure everything is actually connected. Then go into PCB and click on the pin you want to run a trace from, and every place where it can connect to will turn yellow. Then run a solid track between the 2 points you picked and that ratsnest should disappear.
If you are happy with the PCB, you might be able to go to SCH/routing/select all traces/delete, and just redo the traces knowing what you know now. Try it on a copy so you can compare it to the orig.
cheers, like i said it has been 30 years since i did this stuff for a living… tools have changed and this was the first attempt… this is an audio amp for a Cigar Box Guitar so no high frequencies involved. after this i learnt how to get the ground plain to work so i might redo the whole thing… but its a small board and it should work just fine. schematic not really needed at this point. i did a single transistor preamp after this and it went smoother…
Unfortunatly you are correct. Many of the components are user submitted and quality varies. The good thing is that they are available as source and can be fixed (although fixing or making parts isn’t easy it is possible if we care to) and can then be replaced or used. As an example after reading this I cloned a copy of the lm386 part in core, looked at the schematic svg and determined the author had used a path for the two broken terminal elements (which is why it defaults to the middle of the pin element) and replaced them with more appropriate elements to create a corrected part. You can download and import the corrected part in to fritzing (where it will appear in your mine parts bin). You can then use it in place of the broken part in core to get a correct schematic. No need of another schematic package.
LM386_fixed.fzpz (6.4 KB)
Peter
thank you. Very much. i did have a look at editing it myself but i dont have the time to put in to understand it at the moment… one day.
You are welcome, it was fairly trivial for me and its a double win, because I wasn’t aware that a path was an illegal entity type for a terminal definition and am working on a python script to flag errors in parts files so I’ll add this to the error detector.
Peter