DD-2/3 repair notes
Posted: Fri Aug 24, 2018 12:30 am
BEFORE DOING ANYTHING ELSE... what are you powering the pedal with? If you are using an external supply and you are experiencing strange symptoms (pedal stuck in hold, weird repeats, etc.) check the pedal operation with a known fresh alkaline battery.
These pedals, plus the DSD-2 and DSD-3 are known to have weird problems if not used with a high quality regulated power supply. Worse than that - operating from an unregulated supply for extended periods will kill the pedal - this is the most common cause of D6 burning out, and a burned out D6 is probably the most common fault.
Also... don't forget that there is a 5 second delay between when the pedal is powered on and anything working.
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There are more and more dead and sick DD-2 and long-chip DD-3 pedals turning up as they get older and older.
The following list is in the order that I have found to be most common for the DD-2 and long-chip DD-3.
Here is one source for the schematic: http://www.hobby-hour.com/electronics/s/dd2-delay.php
1) Failed capacitors.
SYMPTOM: echoes go up in volume with each repeat and eventually turn into a distorted mess.
CAUSE: C31 (10µF) fails causing the compressor half of the compander to stop working. This allows the expander half to continually expand the signal, raising the volume and turning it into a distorted mess.
SOLUTION: Replace all electrolytic capacitors around the compander – C31, C30, C34. Use tantalum if normal can electros don’t fit.
2) Failed D6.
SYMPTOM: pedal is completely dead. Visible burning around the legs of D6 and nearby tracks. UPDATE: a recent fault indicates that sometimes the pedal can work with a failed D6, but have no repeats.
CAUSE: incorrect AC adapter - specifically an unregulated adapter. MORAL: always use a Boss PSA adapter!
SOLUTION: Replace D6 with an 11V (or 12V) 1W Zener. There will almost always be a need to carefully repair the tracks around D6 – the tracks are quite thin and will burn out when D6 burns out.
POSSIBLE COLLATERAL DAMAGE: If D6 has failed short circuit on an external supply and then the pedal is checked using a battery, the current delivered by the battery into the short circuit can sometimes burn out the contacts in the DC input jack and this jack will need to be replaced. One symptom of this is that, once repaired, the pedal works on the PSA power supply but does not work on battery.
Repaired DD-2. A couple of braided copper strands were run along each burned trace to replace the burned copper:
. . .
3) Failed “mode” switch.
POSSIBLE SYMPTOMS: pedal fails to turn on, pedal only works in “hold” mode, pedal LED comes on but no sound. The only way to know for sure is to use a meter and test the switch in all positions.
CAUSE: age/abuse.
SOLUTION: Order a new switch from Roland and replace.
4) Broken wires.
POSSIBLE SYMPTOMS: no sound, failure to turn on.
CAUSE: Almost always caused by someone swinging the board out too many times.
SOLUTION: Visual inspection, plus GENTLY pull each wire to see if it is still firmly connected. Re-solder those that are broken.
5) Q9 leads broken.
SYMPTOM: No delayed sound. Signal is present at the emitter of Q10, but not at C34.
CAUSE: some pedals have Q9 bent over in the factory to make it fit in the case. This stresses the legs and over time one breaks off.
SOLUTION: Replace Q9. Almost any small signal NPN transistor will do (take care with the pin-outs).
6) Master clock fails.
SYMPTOM: No sound. Use a scope to check the clock is running (pin 63 of the long-chip). The waveform is NOT meant to be “clean” – as long as it is there.
CAUSE: Unknown.
SOLUTION: Replace U8. Note that this must be a “HC” spec TTL chip.
.
.
.
This is my favorite old DD-2. I call it "the pig"... you should have seen it before I cleaned it up. It was covered in some sort of brown gunk - likely old grease from rolling around in the back of someone's truck for years. It also needed repairs #1, #2, and #4 above, plus a new treadle rubber. It would have been heading for the previous owner's trash if I hadn't spent the time on it.
.
These pedals, plus the DSD-2 and DSD-3 are known to have weird problems if not used with a high quality regulated power supply. Worse than that - operating from an unregulated supply for extended periods will kill the pedal - this is the most common cause of D6 burning out, and a burned out D6 is probably the most common fault.
Also... don't forget that there is a 5 second delay between when the pedal is powered on and anything working.
--------------------------------------------------------------------------
There are more and more dead and sick DD-2 and long-chip DD-3 pedals turning up as they get older and older.
The following list is in the order that I have found to be most common for the DD-2 and long-chip DD-3.
Here is one source for the schematic: http://www.hobby-hour.com/electronics/s/dd2-delay.php
1) Failed capacitors.
SYMPTOM: echoes go up in volume with each repeat and eventually turn into a distorted mess.
CAUSE: C31 (10µF) fails causing the compressor half of the compander to stop working. This allows the expander half to continually expand the signal, raising the volume and turning it into a distorted mess.
SOLUTION: Replace all electrolytic capacitors around the compander – C31, C30, C34. Use tantalum if normal can electros don’t fit.
2) Failed D6.
SYMPTOM: pedal is completely dead. Visible burning around the legs of D6 and nearby tracks. UPDATE: a recent fault indicates that sometimes the pedal can work with a failed D6, but have no repeats.
CAUSE: incorrect AC adapter - specifically an unregulated adapter. MORAL: always use a Boss PSA adapter!
SOLUTION: Replace D6 with an 11V (or 12V) 1W Zener. There will almost always be a need to carefully repair the tracks around D6 – the tracks are quite thin and will burn out when D6 burns out.
POSSIBLE COLLATERAL DAMAGE: If D6 has failed short circuit on an external supply and then the pedal is checked using a battery, the current delivered by the battery into the short circuit can sometimes burn out the contacts in the DC input jack and this jack will need to be replaced. One symptom of this is that, once repaired, the pedal works on the PSA power supply but does not work on battery.
Repaired DD-2. A couple of braided copper strands were run along each burned trace to replace the burned copper:
. . .
3) Failed “mode” switch.
POSSIBLE SYMPTOMS: pedal fails to turn on, pedal only works in “hold” mode, pedal LED comes on but no sound. The only way to know for sure is to use a meter and test the switch in all positions.
CAUSE: age/abuse.
SOLUTION: Order a new switch from Roland and replace.
4) Broken wires.
POSSIBLE SYMPTOMS: no sound, failure to turn on.
CAUSE: Almost always caused by someone swinging the board out too many times.
SOLUTION: Visual inspection, plus GENTLY pull each wire to see if it is still firmly connected. Re-solder those that are broken.
5) Q9 leads broken.
SYMPTOM: No delayed sound. Signal is present at the emitter of Q10, but not at C34.
CAUSE: some pedals have Q9 bent over in the factory to make it fit in the case. This stresses the legs and over time one breaks off.
SOLUTION: Replace Q9. Almost any small signal NPN transistor will do (take care with the pin-outs).
6) Master clock fails.
SYMPTOM: No sound. Use a scope to check the clock is running (pin 63 of the long-chip). The waveform is NOT meant to be “clean” – as long as it is there.
CAUSE: Unknown.
SOLUTION: Replace U8. Note that this must be a “HC” spec TTL chip.
.
.
.
This is my favorite old DD-2. I call it "the pig"... you should have seen it before I cleaned it up. It was covered in some sort of brown gunk - likely old grease from rolling around in the back of someone's truck for years. It also needed repairs #1, #2, and #4 above, plus a new treadle rubber. It would have been heading for the previous owner's trash if I hadn't spent the time on it.
.