Schools Experimenter Board problem

[peterb62]

I have built the above board and programmed the Picaxe for the first project where 3 LED's light up in succession.(this is the first project one does as a beginner)
It works however the third LED (green)does not light up.The board accepted the program and OK'd it.It runs but no green light.

The LED is the right way about,all soldering has been re-checked,all switches are on.The program is a copy of what is in the literature.A multimeter check on the other LED's shows a pulse of voltage arriving at approx the time when the LED lights up but no pulse arrives on the green.Can anyone help?

Peterb62(a beginner)

 

[inglewoodpete]

There are 2 possibilities that come to mind. The first is that the LED has been inserted into the board the wrong way around: there is a 'flat' side at the bottom of the LED, indicating the cathode or 0v connection. The other is that you could have a 'dry joint', where the solder has not bonded with the PCB or pin properly.

 

[Michael 2727]

The Peizo is connecyed to the same O/P, does that work ?
If the Piezo works the chip is working. (directly off the O/P pin)

Check you actually have a 330 ohm resistor not another value to that LED.

Check for dust under the switch lever, it only takes a small upward
movement to make the switch break contact.

Apply 3 to 5 V directly across the LED via the usual 330 Ohm
resistor to confirm it actually works, lift SW -2 first.

 

[peterb62]

Schools exp board

Thanks for those ideas,Michael.I will try them tomorrow.I actually cut one of the piezo leads thinking it was causing the fault.I have carefully examined all of the legs of the 8m to see if one was bent under.The switch idea sounds promising.

Peter

 

[peterb62]

Finding a local Picaxe enthusiast

Does anyone know of a Picaxe enthusiast somewhere near where I live?I am in Maryborough Queensland Australia.Hervey Bay is a City of about 55000 & also quite close.Some of my bumbling around would go a lot faster if I had a local contact

 

[peterb62]

For Inglewoodpete-I have checked the orientation of the LED-it's OK.Have also resoldered all the joints & looked at them with a magnifying glass,they look OK.I am following up the ideas of Michael 2727 & will post what happens with that.

 

[medvampire]

Could you please post your code? If you are not getting a signal kinda makes me think it may be a code issue.
Later
Steve

 

[medvampire]

Please post you code. I know you cut and paste but the circuit should work with the code supplied. Check your voltages at each part and use Ohms law to help you trouble shoot each connection. If your meter supports diode test then test the LED using your meter.
Trouble shooting is a step by step process and if you follow the code while reading what the parts of the circuit does you will find the problem.
Later
Steve

 

[inglewoodpete]

Peter, If you are sure that a pulse appears across the LED every cycle as you say in your first post, suggest you try another LED. It's rae that a LED is faulty 'out of the box' but it can happen, It is also possible the LED junction got 'cooked' during the soldering process if you took a little long.

Does the piezo beeper work? Try a piece of code that does a beep or plays a tune. The green LED should light (not brightly) when the beeper is sounding.

Also, when flashing the LED, the piezo will tick faintly every time the green LED turns on and off. This will determine that the PICAXE chip is working OK on that leg (leg 5, output '2' in your code).

Check the resistance of the 330ohm resistor that drives LED3. Important! Ensure the DIP switches are in the 'Off' position before checking this with your multimeter. (anything between 300 and 400 ohms is fine).

Finally, if all else tests OK, do you have another LED (any colour will do) to replace the green one with- leave the leads at full length until you prove it was faulty.

Let us know how you go.

-Peter

 

[hippy]

Two other tricks, put another LED in parallel with the one which isn't working and see if that does ( it won't if the LED failed short circuit ), or take a LED + R and drive that from the PICAXE pin which controls the one which doesn't work.

 

[peterb62]

Please post you code. I know you cut and paste but the circuit should work with the code supplied. Check your voltages at each part and use Ohms law to help you trouble shoot each connection. If your meter supports diode test then test the LED using your meter.
Trouble shooting is a step by step process and if you follow the code while reading what the parts of the circuit does you will find the problem.
Later
Steve

I am trying to upload the code I used for this project and send it to you-I am having some difficulty with this-I presume I send it as an attachment -have tried several times with no success.The code is here in my computer but the problem is using the Picaxe program to send it.This is all probably very obvious to yourselves but it ain't me(at the moment)My apologies for being so useless but I hope to improve.

 

[BCJKiwi]

to post code in a thread;

copy from the Progamming Editor and paste into the thread
put a [ followed by the word code followed by ] at the top,
and
[/ followed by the word code followed by ] at the bottom,
i.e. alltogetherwithoutspaces

All the options and smarts you can use in the Forum are listed in
FAQ (on the top menu)
vB Code List

It's well buried so here is the link;
http://www.picaxeforum.co.uk/misc.php?do=bbcode

 

[westaust55]

Peter,
From your first post:

A multimeter check on the other LED's shows a pulse of voltage arriving at approx the time when the LED lights up but no pulse arrives on the green.

I assume that the Piezo also never worked, before you cut the lead to it.

Have you checked at PICAXE 08M physical pin 5 to see if the pulse for the green LED is output from the PICAXE chip.

From my past experience with DIP switches in old PLC card cages and some more recent equipment, they sometime do not make good contact.
Suggest that you move the switch (No 2?) back and forth (= ON and OFF) a few times and see if that resolves the problem.

 

[peterb62]

Problem solved!

A friend visited and checked the circuit board for me -he found I had a bridge on the underneath of the circuit board.I had just not seen it.Thanks for your help everyone.Now I will go on to those tutorials in the booklet-one to ten & try not to do this again.

Peter

 

[westaust55]

Great to see/read that your problem is resolved and that you are now underway.

Feel free to ask more quessions as you find hurdles in your path. There are many here who can help.

When you do have a problem. while being succinct in posts, try to either:
1. post your program for others to read thru,
2. provide a photo of the physical circuit,
3. give a clear explanation of the actions and results - your first post was fairly good in that respect to my reading.

Using "please" and "thank you" will help to keep those who freely give their time in helping you on side.