Hi BB I have been posting about your build on Maverick (under another name) Where in the UK are you? I have built 2 of these and an ACA Mini and ACA Redux.
Looking at your picture of the PCB, I zoomed in on R13. 10k resistor should be brown black black red plus tolerance band.
To my eyes the bands look like brown black black violet, which translate to 100 x 10,000,000 Ohm, much, much more than 10k Ohm.
Or perhaps it is grey black black violet brown, which translate to 800 x 10,000,000 Ohm.
Or perhaps it is brown violet black black grey, which translate to 170 Ohm.
Please look at R13 again, and remeasure its resistance. If the colours are correct then the resistance is not 10k Ohm. A much higher resistance would not allow enough current to light up the LED.
With power on measure the voltage with one probe on the LED+ pad and the other probe on the LED- pad. If it shows the power supply voltage (18.5V previously measured by you) then that indicates that power is available at the LED pads. A LED connected to the pad should light up. Do you have more than one LED? Try a different LED if you have another.
Another test you can do is if you have an 1k to 2k resistor, connect that to the LED pads in place of the LED and measure the voltage across the LED. If the LED circuit is working properly you should see a voltage of around 1 to 2V.
Another test you can do is if you have an 1k to 2k resistor, connect that to the LED pads in place of the LED and measure the voltage across the LED. If the LED circuit is working properly you should see a voltage of around 1 to 2V.
18V5 is there without Led
DVM Is high impedance, so no significant current through resistor, so no voltage sag across resistor
connect LED properly and you'll get voltage sag, exactly why resistor is placed there
DVM Is high impedance, so no significant current through resistor, so no voltage sag across resistor
connect LED properly and you'll get voltage sag, exactly why resistor is placed there
Hi.
Thanks to everyone for your suggestions..
I have tried a different led from the same batch.
It works. I now have 2 working leds on my amp. Hoo ******* Rah!....
BUT.....
Here is a pic of the led that will not work in my amp, connected to 2 AA batteries, 3v.
I actually removed the new working led to try this one again in the amp and it won't light up.?
Sincere thanks for all your patience.
Rik
Thanks to everyone for your suggestions..
I have tried a different led from the same batch.
It works. I now have 2 working leds on my amp. Hoo ******* Rah!....
BUT.....
Here is a pic of the led that will not work in my amp, connected to 2 AA batteries, 3v.
I actually removed the new working led to try this one again in the amp and it won't light up.?
Sincere thanks for all your patience.
Rik
After decades of doing electronics, I'm sure in just 2 things .............. nobody on tis Earth is able to be stupider than me and - second - I don't believe anyone, including me, I believe just to my DMM
moral of the story - be humble, stay humble, read advices carefully, and sky is the limit
leave ego aside and only then you'll see how much of fun is falsely accused of being mockery
moral of the story - be humble, stay humble, read advices carefully, and sky is the limit
leave ego aside and only then you'll see how much of fun is falsely accused of being mockery
My DMM (aswell as 3v battery) is telling me that that led (the one that won't light up in my amp) works.