MK103, Built, but I think I fried something

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1

So I got the MK103 built, and is currently being powered by a wall plug that I took from an old portable phone.

When I turn it on, the lights simply stay on, turning the pot has no apparent effect other than making the lights flash erratically while it’s being turned.

I was just reading a couple posts, is it possible I’ve burned out the output transistor or is it just the wall plug i’m using making noise?

I would like to have this hooked up in my car, but would first like to know if I can hook it up in my car, and if I broke something when soldering the parts on?

2

Due to the high sensitivity, the unit must be operated on batteries or from an extremely well regulated power supply for proper operation.

3

I have added in a 1000uf cap across the main power leads in an attempt to fix the noise but it has not worked. I’ll pickup a battery today if I can, but the unit seems to behave erattically as if it’s more than just line noise.

I removed the mic to test, and the lights remain dimly lit with no mic, when I adjust the pot the lights flicker, flash and generally go nuts with no discernible pattern, then remain more brightly lit up once the pot stops moving.

is this seriously all because of the wallwart?

is there anyway to make the unit less sensitive if this is the case, I intend to use this in my cat really close to subwoofers to control other lights, I need something that will handle the a high SPL(sound pressure level) without keeping the lights totally solid… basically much less sensitive.

would powering this from my car cause the same types of line noise?

4

ok, I shorted out one of the leds by mistake, and now it does nothing. Is it possible I’ve killed the output transistor?

5

That is likely but hard to tell without investigating your assembly.
For best results, replace all transistors, just to be sure.

6

ok let me re-phrase, highlighting my absolute stupidity on this one, because it’s probably going to help more…

I took the 1000uf cap, and wile it was charged, and the unit was plugged in jumped one of the LEDs… they lit up brightly, and then slowly died down as the cap discharged… then it stopped working.

so is it easier to figure out which part of the unit my dumb a** killed?

7

Probably just the led.
Short the defective led, the others should work fine, if there are no more fried components.

8

the leds all work fine, nothing happens when power is applied

I picked up 4 replacement transistors. they arent 547/557 but equivalents since the BC models are British numbers

the only difference is 5v. the transistors i bought are 40v rated, but handle higher current.