Need Schematic - Boss DD-3 Delay Pedal

[Red Barrington]

My Boss DD-3 quit passing wet and dry signals. No sound out except from the 'direct out' jack. The LED still clicks on and off and the power seemed to be ok. I found +9 Volts off the wall wart and +5 in a few other spots (Though I'm not sure where the regulator is. The chips aren't named in a straightforward way). The power supply diode seems to be doing its job.

After attempting to trace the signal and check the wiring/jacks, I've started to get lost. It's difficult to follow the traces with these tiny surface-mount parts and the jungle of wires piled on top. I'm not even sure which jack is the input and which is direct out at this point. I should've written that down when I started.

Long story short: Does anybody have a schemo out there? I managed to find a DD-2 schematic and that's helped some, but the design seems to have changed. The component numbers are different.

Thanks for reading and I hope one of you can help or offer advice.

RB

[Red Barrington]

In the interest of sharing info, I'll go ahead and post the fix. I managed to get my hands on a dd-2 schematic which helped immensely. First off, it let me know that I had re-wired the jacks incorrectly after they started breaking off. Oops.

Anyhow, there's a main opamp that buffers the output in and out. It's an LF353. I noticed the first audio out was asymmetrically clipping. At the 2nd audio out, it was practically gone altogether. Further investigation revealed the "1/2 Vcc," was being dragged down to less than a Volt. This Voltage is supposed to sit at 4.5 Volts or Virtual Ground between 0 and +9 VDC.

You can check pins 3 and 5 on this IC to check these Voltages.

The Vcc Voltage only goes a few places, usually through large resistors. The exception is IC1. It is directly connected to pins 3 and 5. I popped out IC1 (the LF353) and the Vcc jumped right back up to 4.5 Volts. Then I put in a new chip and everything's working hunky dory.

I bet this failure will happen to someone else out there since this IC is connect directly to the output. It's susceptible to zaps. And the 1/2Vcc isn't really buffered all that well.

Ok, that's enough for now. Hope this helps somebody out there!

RB

[delb]

have you tried "free information society? i found lots of boss related schematics...free!

[vintagekiki]

Boss DD2/3 First Edition Sept. 1986

[soundforsound]

Hi,

My DD-3 Version 3 . doesn't power up . nothing. however it is missing IC1. Does anyone know what the IC is?

[91lespaul]

Red Barrington,

I think I have the exact problem you described, lights up fine, Direct Out works fine, but hooked up to Output and nothing.

You stated "The Vcc Voltage only goes a few places, usually through large resistors. The exception is IC1. It is directly connected to pins 3 and 5. I popped out IC1 (the LF353) and the Vcc jumped right back up to 4.5 Volts. Then I put in a new chip and everything's working hunky dory."

I'm looking at the schematic and it lists IC1 as a 5218, not LF353. Are these interchangable chips, or is there a difference in the schematics?

Thanks for any help.