Wow quick reply thank you. The part was destroyed during removal. 5V on the board so I was assuming it had a built in dropping resistor. I am a bit remote, Cork Ireland, and the two big locals Radionics and Farnell do not have a 3mm 5V Blue. Would 3.2V work safely? It is no big in that I can go red, but I would prefer to keep the original appearance.
Measure the DC voltage across the other LEDs. Are they all blue?
Do they have the same DC voltage across them? I kinda doubt they have internal resistors.
A blue LED can drop around 2.5V to 4V, depending on the device, so you want the right one.
What is the brand and model of equalizer?
Post some photos.
Do they have the same DC voltage across them? I kinda doubt they have internal resistors.
A blue LED can drop around 2.5V to 4V, depending on the device, so you want the right one.
What is the brand and model of equalizer?
Post some photos.
Don't take a few ten's of a Volt too serious with LED. Worst thing that can happen is to blow a 12 Cent part. You will see if it is extremely bright. Otherwise it is fine. If repairing something like car audio or HIFI stuff, always thing cheap. A special part with a build in resistor will cost 25 fold of a regular LED. So what did the (Chinese) manufacturer choose in 100 from 95 cases?
LEDs are normally driven by current. There is usually a resistor somewhere that sets the current. The current is then the voltage difference between the supply and the LED divided by the resistance.
LEDs are not like light bulbs, the color is a result of the physics of the semiconductor inside.
So each color of LED, and each different process for a given color, will have a different DC voltage drop.
That is why the measured voltage is important. Measure the DC voltage across the remaining good blue LED.
You should choose a replacement blue LED with a similar characteristic DC voltage.
Measure the remaining good blue LED to find out the suitable DC voltage.
There are definitely dropping resistors (of differing values) in series with each of those LEDs.
Since it sounds like you cannot change the smt resistor, you must use an LED with a similar DC voltage drop.
So each color of LED, and each different process for a given color, will have a different DC voltage drop.
That is why the measured voltage is important. Measure the DC voltage across the remaining good blue LED.
You should choose a replacement blue LED with a similar characteristic DC voltage.
Measure the remaining good blue LED to find out the suitable DC voltage.
There are definitely dropping resistors (of differing values) in series with each of those LEDs.
Since it sounds like you cannot change the smt resistor, you must use an LED with a similar DC voltage drop.
If you measure 5V on both wires with the LED removed, this doesn't mean you need a 5 Volt part. How much you measure at these points, with the LED installed, depends on the resistor in line with it and the LED type.
If you find a LED of similar size and color, there is a good chance it will fit. Don't overcompilcate simple things. Test fit the new LED, measure the voltage and you know better...
I have problems to call KT equalizers "expensive build". Even if they didn't come from China. I had one a while ago.
If you find a LED of similar size and color, there is a good chance it will fit. Don't overcompilcate simple things. Test fit the new LED, measure the voltage and you know better...
I have problems to call KT equalizers "expensive build". Even if they didn't come from China. I had one a while ago.
No manuals for that one, so a higher DC voltage blue LED (see its spec sheet) would be most safe.
Well that has been extremely helpful. I did train as an electronic tech a handful of decades ago, so this was refreshing, literally. Physical Graphic Eqs are all but gone now, replaced by DSP controlled on a Tablet, Phone, or Desk Screen. I have always chosen KT when possible, even Mastered an Album using a very early KT, Urei 1178 and Lex 480. Inside this one, the metalwork looks cheap and has sharp edges. Nice on the outside though, including the one Blue f........ LED and knobs that light when pushed. The facers are long and smooth and firm. The sound is, I have to say, reluctantly given the Chinese outsourcing, excellent. The extra notch filters etc. make good KTs claim that this was a 'development' of the line. I think I saw a 4V LED so I will buy a couple of options and start with that.
Muchas gracias amigos. DD
Muchas gracias amigos. DD
Put a 5 kOhm resistor in series with the new LED and that will drop the voltage and limit the current to the LED. The voltage drop at the LED junction is fixed at a couple of volts so the resistor will drop the remainder of the 5 volts. The resistor will then limit the current to (5V - LED Voltage) / resistance. If the LED is not bright enough, decrease the resistance.
