So I've been asked to rehouse this boss chorus that was really old and grungey, footswitch was dead, wasn't grounding etc. Everything has gone smoothly except one thing.
When I replaced the LED (old led worked fine however it was replaced due to the size), the new one doesn't light up - even when the effect is working and engaged.
I thought oh silly me, the LED's resistor is clearly incorrect - So I swapped out R51 (3.9k) for a 390 ohm. Still no luck.
This is a schematic and board layout here http://www.hobby-hour.com/electronics/s/boss-ce2b-bass-chorus.php
I'm a little puzzled!
Thanks!
> the LED's resistor is clearly incorrect
Why?
More likely wired backward.
I put this down as I had other projects to tackle but upon returning to this, I have come to the conclusion that I must take into account the zener diode when calculating which resistor to use for the LED?
Is that correct?
If it is not lighting at ALL, the LED is backward (or dead).
If it lights "dim", the resistor could be smaller.
> take into account the zener
Well, that's why BOSS paid its engineers the big Yen, to pick a good resistor, right? And it did work before. And while LEDs do vary a little in brightness for current, it should "glow" even if dim. No light really suggests wired backward.
-OR- you replaced a red LED with a white one?
the older model boss pedal (aca is the number for the P.S. ) ran on 12 volts for the power supply , but still used a 9 volt battery .
IF , one has an older style 12 volt ACA type adapter power supply boss pedal , it isnt too challenging to JUMPER over ( bypass ) the resistor to enable it to fuction properly with a 9 volt power supply or P.S.
there is a resitor and a diode for the led to drop the power for the led , initially the boss aca ps put out something like 14 volts with no load , so if one bypas' this resistor , the led will light with a mere 9 volts .
i did this on a CE2 i got for a quarter at a garage sale , initially , the effect functioned properly , but the led was not lit , or actually very very dimly glowing . i think , if memory serves .
i am going to take the easy road and post a single link , but i am sure one could find a few more how too's for this not so rare modification .
http://jorgezorro.blogspot.com/2009/12/boss-aca-to-psa-power-supply-mod.html
i seem to remember it being a single resistor swap on my ce-2 but this was years ago , and i cant not remember ...
good luck sir .
http://hugeracksinc.com/forum/viewtopic.php?f=1&t=21764
It's funny, I just assumed it was 9v because when I plugged it in - it worked!
yeah i had this same situation and ran that chorus for a while then it dawned on me , ... there is a reason that led is not on so i googled and read up on it . i was a bit nervous as i always am when opening up something , but it isnt too difficult of a mod . i changed out the led for a different color as well , which was proilly a bad idea for the resale value as it is an older model but ... i can always chop in the ugly red one at any time , it looks great with the pale blue one thats in there now .