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]

Solution

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]

boss schemetic

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

[vintagekiki]

Boss DD2/3 First Edition Sept. 1986

[soundforsound]

DD-3 Version 3

Hi,

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

[91lespaul]

No Output

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.

[upstairsdave]

DD3 LED not staying on`

Greetings,
I have a Japan made DD3 that the LED does not stay on when I push the on/off switch down. Is this a transistor/solid state device that is defective or is the switch a latching type switch that should remain closed when pushed down and then remain open when pushed down again? Where can I get a switch for it?
Thanks
Dave

[Bill Moore]

I believe all the Boss compact pedals use a momentary switch.
This might help.
FET switching

[upstairsdave]

Thanks Bill.
I used the ohm meter and it is a momentary switch. The article seems pretty good as far as I have read so far. Well, back to my homework
Dave

[upstairsdave]

The FET page didn't address the LED light coming on when the on/off switch was activated. The light comes on when I push the on/off switch down and then the LED light goes off when I release the switch. I don't think it's a defective switch. It must me the device it tells to turn on is not turning on to keep the LED lit.

[doctor]

The FET page didn't address the LED light coming on when the on/off switch was activated. The light comes on when I push the on/off switch down and then the LED light goes off when I release the switch. I don't think it's a defective switch. It must me the device it tells to turn on is not turning on to keep the LED lit.

The problem written by Red B. is well known failure.
About 90% of all DD-3 received for repair by authorized
service laboratories have this single malfunction.

The first check, which should be performed when DD-3 has
not output signal, is Vbias measurement on the IC1’s pin 3.

If the voltage is less than 4.2VDC, the IC1 must be replaced.
The recommended chip is NJM4580.

[upstairsdave]

Hi Doc,
Thanks for writing. Do you know what circuit is designated for receiving the grounding of the on/off switch to keep the LED light on?
I've got a dead CE-3 that the light doesn't even come on when the push the switch. I think they both died when I truned on the power one day. Maybe a power supply issue that hit both of them at the same time.
Hope this helps
dave

[Jazz P Bass]

IC9 is a "flip-flop" device.
It will hold a certain output state until the next trigger at the input.
Look at the schematic.
We are dealing with logic levels here.
A "high" means a voltage near the power supply rail.
A "low" means a voltage near ground (zero volts).
O/k.
R58 is tied to +9Vdc.
So input pin 1 (IC9) is "held" high.
Output pin 2 is initially "low".
An input from the Foot Switch will pull down pin 1.
That will tell the circuit (IC9) to switch states.
So the output (pin 2) will toggle between a low & a high state. (LED is now on)
Unit Off. Unit On.
Be aware of pin 5. This is the Reset pin.
It must be "low" for the IC to function.
There is a small circuit there to momentarily allow the reset pin to go "high" at turn on. That is the "mute" circuit.
Now that you have a circuit description, you can check the voltages of IC9.
Pin 1: held high, goes low at ft sw input.
Pin 2: must toggle according to pin 1's input.
Pin 5 must be low for IC to function.

[upstairsdave]

Wow!! Awesome explanation Jazz P B. Maybe this solid state thing is over my head. I know a bit about solid state devices but not enough to pull diagnosing this one. I'd like to learn more and have a pretty cool book called Basic Electronics Theory by Delton Horn.
Do you know anyone that repairs these pedals. I hate to throw it out. The CE3 and the DD3 were both born in Japan.
Take care
D

[Jazz P Bass]

If you have a volt meter, then you can diagnose whether or not IC9 is functioning.
Set the meter to read Volts DC.
Hook the Black lead to zero volts (ground).
Start measuring the points that I indicated with the Red lead.
Is pin 1 high.
Does pin 1 go low when the switch is depressed.
Does pin 2 flip flop.
Is pin 5 low.