Problems on my Boss DD-3

[MeTaLCaM]

Hello !! (Excuse-me for my poor English...)

So I bought a DD3 last week, but the effect doesn't works at all...

I listened that it could be the 78L05... But I opened the DD3 and I didn't found this chip...

I think I have another version of the DD3 (CPU is behind...), and because I saw the DD2/3 Shematics and, for example, on my DD3, the C47 Condensator is linked to a resistor... But not on the schematics (It's linked to the ground...)...

So what is the chip or any component who take the 9V to translate into 5V ?

Thank you

[MeTaLCaM]

up !!

[Mark Black]

The 78L05 looks exactly like a transistor in a TO-92 case with three leads, rather than a DIP chip.

Hope that helps!

[Mark Hammer]

http://www.national.com/ds/LM/LM78L05.pdf

[MeTaLCaM]

Ok thank you...

I aquired a voltmeter so I tested directly on the processor... I see 5V... (and when the pedal is switched off)...

But, I don't why, when i push the pedal, le voltage is 6.5 V just behing the button (a purple cable), and when the pedal is switched off too... Why ?

There isn't another cable who link the button with the system... It's unbelievable...

[cjlectronics]

I don't understand what you are trying to describe? Are you measuring 6.5v on the 5vdc bus when the pedal is switched off?

The pedal will turn on if a battery is installed (or AC adapter) and a guitar cord is plugged in. I'm sure you are aware of this. When the pedal bypass switch is switched in (the LED turns on) your are doing two things:
1. Activating a JFET to allow delayed signal into the output circuit
2. Activating a bit on the CPU to tell it the FX switch has been pressed. If your mode switch is set for HOLD, then another bit is actuated to tell the CPU the HOLD feature is desired.

From your original post, C47 is on the +5v bus in the DD3 original version. The version you have (the square chip mounted on the solder side of the PC board) C47 is in the input signal path right before the JFET input buffer.

Monitor the 5v at pin 14 of IC4 which is the 74HC00. Then stomp on your bypass switch.

[MeTaLCaM]

On the PIN 14 of this chip...

6.60 V, when the pedal is switched on... and when it's switched off too... (switched off = the led turns off)

So ? What can I do T_T ?

[cjlectronics]

Replace the 78L05.

[Dirk_Hendrik]

Would you be able to tell me the version of your DD3?

Or, simpler, is it the version with the big, boardwide chip?

coz in that case, when they get a reversed polarity power supply other than that the reverse polarity diode burns out, the 78L05 dies, there's a couple of electrolytics that tend to die as well. After a while this will show on the copper side of the board as the copper turns black (under the green transparent) laquer.