My final product was flawed
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ldanley 3 months ago
I did not pay attention to the PCB lay out but when I got my product the PCB layout did not match the Schematic and it had two positive out puts on both sides of a capacitor, which burned up my chip.. Please help..
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andyfierman 3 months ago
We cannot help you because your project is private so that not you can see it. In the Tutorial and the FAQ, we advise all users to check their work at every stage and especially before submitting for PCB manufacture. Sections (4), (5) and (6) of: [https://easyeda\.com/andyfierman/Welcome\_to\_EasyEDA\-31e1288f882e49e582699b8eb7fe9b1f](https://easyeda.com/andyfierman/Welcome_to_EasyEDA-31e1288f882e49e582699b8eb7fe9b1f) are devoted entirely to checks that should be carried out both before converting a schematic to a PCB and then before submitting a PCB for manufacture. I suggest you read: [https://easyeda\.com/andyfierman/Welcome\_to\_EasyEDA\-31e1288f882e49e582699b8eb7fe9b1f](https://easyeda.com/andyfierman/Welcome_to_EasyEDA-31e1288f882e49e582699b8eb7fe9b1f) for guidance on what you should have done and how to do it right next time.
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andyfierman 3 months ago
Sorry, Autocorrupt messed up the first sentence of my post: "We cannot help you because your project is private so that only you can see it."
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andyfierman 3 months ago
You also should update your version of Chrome. It is seriously out of date and may not only compromise your experience of EasyEDA but also the security of your computer.
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ldanley 2 months ago
I forgot how to make projects public. Please let me know... Sorry for the delay..
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andyfierman 2 months ago
[https://docs.easyeda.com/en/Introduction/Share-to-Public/index.html](https://docs.easyeda.com/en/Introduction/Share-to-Public/index.html)
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ldanley 2 months ago
it should be public now
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andyfierman 2 months ago
Please post the link to your project and indicate which clearly Schematic(s) and PCB(s) in that project you are asking about.
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ldanley 2 months ago
[https://easyeda\.com/editor\#id=eb1eea022cba4f50b796861a58df8929\|b9c41e4154dc42eaa92487547cad8f5c](https://easyeda.com/editor#id=eb1eea022cba4f50b796861a58df8929|b9c41e4154dc42eaa92487547cad8f5c) alpo alpo christmas
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andyfierman 2 months ago
@ldanley, Sorry but there is a lot wrong with your design. 1. The 555 timer and 74LS164 have no decoupling capacitor from the VCC to ground pin.  2. The decoupling capacitor, C3, from pin 5 of the 555 timer to ground is only 47pF, way lower than the recommended value. 3. It is not clear what type of capacitors you have specified for C1 and C2. Neither the Schematic Symbols nor the PCB Footprints have polarity identification markings. If they are electrolytic capacitors then they must have polarity identification markings. 4. Except for Q8, the pin mapping of all the transistor schematic symbols to their PCB footprints are wrong: collector and emitter pins are reversed. 5. Tracks are unnecessarily narrow. 6. The PCB is unnecessarily spread out. 7. Combined with the thin tracks and lack of decoupling this is likely to cause erratic behaviour due to switching currents especially from the 555 timer. 8. You have a copper plane on both the top and bottom layers. Both are assigned to the GND net but nowhere in your circuit is there a net labelled GND. So you have two copper planes that do not connect to anything and therefore serve no electrically useful purpose. 9. I do not understand why you say that "the PCB layout did not match the Schematic and it had two positive out puts on both sides of a capacitor". 10. The PCB layout does match the schematic. 11. I can see no nets that suggest that "...it had two positive out puts on both sides of a capacitor".
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ldanley 2 months ago
My circuit has been proven to work. using the schematic and a prototype board.. I came to EasyDA to produce a professional copy.. Again, the Schematic is sound...
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andyfierman 2 months ago
You posted on the forum because your PCB did not work. It did not work because there are mistakes in the schematic. One (fatal) mistake is that you did not notice that the Schematic Symbol pin to PCB Footprint pad mappings for the BC337 transistors is wrong. In an EDA tool, checking symbol to footprint mappings is an essential check. If you get that wrong then the PCB will be wrong. Just because a circuit "works" on a prototype board, that does not mean it is correct or will work on a different layout. Most people judge the success of their PCB by the fact that it does what they expect it to, not by analysing how close it is to not doing it. Omitting essential supply decoupling capacitors is one way of pushing any circuit firmly towards not working. Please study the datasheets and the manufacturer's recommendations for decoupling for the 74LS family of logic devices and especially, 555 timers. See also: [https://easyeda\.com/andyfierman/Power\_supply\_decoupling\_and\_why\_it\_matters\_\-451e18a0d36b4f208394b2a2ff7642c9](https://easyeda.com/andyfierman/Power_supply_decoupling_and_why_it_matters_-451e18a0d36b4f208394b2a2ff7642c9) To avoid making mistakes like this, we publish essential Schematic and PCB checklists. Please see the Tutorial or (4), (5) and (6) in: [https://easyeda\.com/andyfierman/Welcome\_to\_EasyEDA\-31e1288f882e49e582699b8eb7fe9b1f](https://easyeda.com/andyfierman/Welcome_to_EasyEDA-31e1288f882e49e582699b8eb7fe9b1f)
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ldanley 2 months ago
Before I came to easyeda , I design the circuit on a prototype board,. It' worked perfectly. I came to easyeda to upgrade the circuit to a printed board. It is not my schematic that's wrong.... Even if the transistors were wrong the 555 should work regardless under a test.
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ldanley 2 months ago
Please help
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andyfierman 2 months ago
Since all your board is through hole it'd be easy to connect up just the 555 timer section and power that up on it's own. Check the pin out between the datasheet and your PCB. If it's all wired up correctly but oscillates erratically, try a 10uF decoupling cap directly across the VCC and GND pins.
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ldanley 2 weeks ago
Andy, do you all do assembly and testing? If so at what cost?
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andyfierman 2 weeks ago
PCBA is on the EasyEDA roadmap but is some time away. EasyEDA does not do Test work. Depending where you are and your  price range, I might be able to help. Have a look at: [http://signality.co.uk](http://signality.co.uk) and contact me via there. :)
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andyfierman 2 weeks ago
@ldanley, If this is the project that you are asking about assembly and test for: [https://easyeda.com/ldanley/alpo](https://easyeda.com/ldanley/alpo) then I'm sorry but I cannot offer any support for it because you do not appear to have made any of the changes recommended in my earlier posts. You have also not provided any Design Requirements or How It Works information as recommended in: [https://easyeda.com/forum/topic/How-to-ask-for-help-and-get-an-answer-71b17a40d15442349eaecbfae083e46a](https://easyeda.com/forum/topic/How-to-ask-for-help-and-get-an-answer-71b17a40d15442349eaecbfae083e46a)
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MikeDB 2 weeks ago
@andyfierman Nice website - hadn't seen it before
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andyfierman 2 weeks ago
@MikeDB, Thank you! :) p.s. Must have an email chat with you about synth modules...
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