two unrelated minor problems

pleiser

pleiser

Senior Member
first problem: the serial OLED I got from techsupplies (the limited time green version) makes a very high piched noise (the type you can barely hear that drives you crazy). Is this a common problem? what would a good solution be? where could I get a replacement now that techsupplies no longer has them?

problem 2: macaxepad seems to have a problem with #rem,#endrem, a few of them work but adding any more and it doesn't detect the endrem, it will stop being green after the endrem, but it will stay comented. eg:
Code: 
main:
goto aftercomment
#rem
this rem will not stop
#endrem
aftercomment:
goto main
will cause a syntax error: error: label not defined - aftercomment.
if I remove the rem and endrem it works as expected but I have to comment each line seperately (with ')

~Patrick
 
N

nick12ab

Senior Member
pleiser said:
first problem: the serial OLED I got from techsupplies (the limited time green version) makes a very high piched noise (the type you can barely hear that drives you crazy). Is this a common problem? what would a good solution be? where could I get a replacement now that techsupplies no longer has them?
Click to expand...
I haven't noticed this effect on a 16x2 Winstar OLED. However the OLEDs do use switching regulators to generate the high voltage required by the OLEDs and these switching regulators use inductors (which can hum). You should be able to see the single inductor on the PCB.

If you are using this brightness mod, set the brightness back to the original level for troubleshooting. Make sure that you have a decoupling capacitor and bulk capacitor fitted on the (PICAXE) power rails and that if you are using an AXE033 the PWR jumper is shorted. Ensure that the power supply is a regulated 5V.

It could also indicate a poorly made inductor - try replacing the inductor with another of the same value.
 
pleiser

pleiser

Senior Member
I have the 20X4 AXE134G model,I am not using the brightness mod, it is currently getting 3.78 volts (batteries low), but also had this problem at full (4.5V) voltage. What does an inductor look like, how hard is it to replace, where would I get a replacement?
 
N

nick12ab

Senior Member
pleiser said:
I have the 20X4 AXE134G model,I am not using the brightness mod, it is currently getting 3.78 volts (batteries low), but also had this problem at full (4.5V) voltage. What does an inductor look like, how hard is it to replace, where would I get a replacement?
Click to expand...
It will look like one of these - probably the one in the bottom left. They are not expensive and most electronics suppliers sell them.

But before you replace the inductor, try the candle wax mentioned above and also how loud is the noise? If you can only hear it in a dead silent environment then that may be normal.
 
G

geoff07

Senior Member
Before modifying the part I suggest a conversation with the supplier, as if they have supplied a faulty part they might want to remedy the matter. If they have stopped supplying them, you may have discovered the reason.
 
D

Dippy

Moderator
Absolutely. If they were received faulty and you want any chance of a warranty replacement or refund the last thing you should do is attack it with a soldering iron!

Why were they a "limited" version? Were they low-cost end-of-line?
 
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geoff07

Senior Member
Then they were sold as full-spec parts, just of a different colour. Personally, I would give them a chance to demonstrate their customer service credentials!
 
fernando_g

fernando_g

Senior Member
geoff07 said:
Before modifying the part I suggest a conversation with the supplier, as if they have supplied a faulty part they might want to remedy the matter. If they have stopped supplying them, you may have discovered the reason.
Click to expand...
Absolutely. Nowdays most SMPS switch at a higher frequency, usually much higher, than 100 Khz. Not even a dog will hear that. Probably a bat.

When a SMPS "whines" it is because of a phenomenon called sub-harmonic oscillation. This is almost always caused by either losing the slope compensation or by an incorrect feedback network. Caused by defective component, that you should not be the one to diagnose it.
 
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