Boss CE-2 LED is VERY dim

[deke99]

Hi all,

I have an old Boss CE-2 and the LED went south.  So I went to the shack and picked up a 2 pack of 3mm T1 LEDs (3V 15mA).  I replaced the LED and now I find that the LED does light up, but it is VERY dim, to the point where you can only really see it lit up if you are in the dark.  The pedal itself works fine.  I measured the input to the LED and this is what I get:

Board connection 13 (LED anode) measures 2.5V and 11mA in reference to ground.  I would think this would be enough to power the LED, but perhaps not.  Does anyone have any experience with this?  Any suggestions.  I can live with the pedal as it is, but I'd rather have an LED that works!

Thanks!
Derek

[m_charles]

not positive, but your led was/is probably fine. You need a 12V or "Boss ACA" adapter for some of their oldies. Or you can daisy chain it with "modern" effects and you'll get all the juice.

chuck

[deke99]

Thanks for the reply.  I'll do some research on the 12V input.  I've always run it at 9 volts and the LED was properly illuminated and I don't want to risk frying the pedal.  The radio shack LED's are listed as Lo-Intensity, so perhaps I need to just find a high intensity LED.

[Dave Simpson]

Is the LED brighter if you power the pedal with a 9 volt battery?

[Ice-9]

If there is a problem then raising the voltage to 12v isn't going to help, i would check the schematic as you may need to change other components in the led circuit. maybe a lower value resistor if the specs on your led differ from the original. I will look at the schematic to see if i can spot any other reason, as boss pedals have a flipflop switching im not sure how the led is set up with out looking at the diag.

[Ice-9]

I've just looked at the CE-2 schematic and the led is switched from a transistor Q8 on the diagram, it also has a zenner diode in the power to the led. ( i think this is there to allow the led change illumination if the battery is going flat) anyway if the pedal is operating normally apart from the led then the only other components are the zenner, the transistor and a 3k9 resistor that could be at fault.

[deke99]

Thanks for the insight Ice-9.  I did check the 3.9K resistor and that measured spot on.  I'll try swapping out the transistor and/or diode to see if that helps the problem.  Thanks!!

[MikeH]

You should have just replaced the LED with a sweet bright-blue one so you can sell it for double on ebay 

[petemoore]

You should have just replaced the LED with a sweet bright-blue
  popping noise probably won't happen..
  First thought I had too...put a bright one in there, if that is easy.
  Digging transistors out of the circuit...sound like a possible 'youch' to try on a CE-2 if there's a less intrusive alternative.
  A BP system is fine when it works, and I haven't tried working on them, I've read enough to not want to go there.

[Lee_ranaldo]

it's normal on Japanese or old Taiwan BOSS pedals that needed the ACA Boss Adapter to have that problem.

I had no clue when i was repairing an old ACA Turbo Overdrive OD-2 with the same problem.

- Replaced the Led : Sane
- Replaced the Zener Diode: Nothing
- Replaced the 2SC945 transistor: Same problem again

Until i discovered that there is a small circuit with a resistor and diode connected to ground to "pull down" the voltage of the ACA boss adapters (12V)
to 9 volts. To resolve the problem you simple connect another pedal using the same power supply so the ground path is complete and full 9V on the CE-2 Chorus Pedal.

If you use batteries , if everything it's ok inside, you should see no problem at all.

[deke99]

Wow, who would have thunk it?!!  I normally had another pedal connected after it that ran off the same daisy chain supply and I never hooked up that second pedal after replacing the LED.  I'll try that tomorrow, since the pedal is now in my rehearsal space.  Thanks for the tip Lee!

[deke99]

Sure enough, when powering the pedal with a battery, all was fine.  Since I don't have an unregulated 12V power supply for the pedal and don't want to use batteries, my solution was to bypass the 3.9K/diode portion of the circuit.  In the case of the CE-2, all that was involved was adding a small little jumper wire between wire connectors 3 & 4.  Now I'm good to go.  Thanks to everyone for your help and insight!