Boss DD3 (Japanese Made) Problems

[fender182g]

Hi guys,

I didn't know where to post this so i just thought i would put it here.

I am not an expert on electronics but do enjoy building things and trying to fix guitar pedals that are broken.

i have a boss dd3 that is really old since it was also made in japan, but now it is not working. the problem is that when you are plugged into it nothing happens other than a big buzzzz. but thats only when the power supply i plugged in. i tried a batterie and it still did not work but there was no hum. the led does not go on at all and the only time i can get signal through it is when i plug into the direct out jack. i pulled it apart and could not see anything wrong but i could smell that famous burnt electronics smell. i plugged it in while it was open and i felt the circuit board for any hot spots and in one part it nearly burnt me. anyway i was hopping someone could maybe try to help me out. i have attached some pics. the red circles indicate where it got really hot and smelt bad!

Thanks

[zombiwoof]

Is it possible that you at some time plugged in a power supply of the wrong polarity?.  If so, you could have burnt out the reverse polarity protection part of the circuit.  The Japanese pedals like that also require the older ACA Boss adapter, which put out over 12 volts, and the voltage is reduced by a couple of components to the regular 9+ volts.  However, if you plugged in the Boss PSA type adapter, that only supplies about 9 volts, the only thing that would happen is that the LED would not light up all the way, the pedal would still work to a certain extent, only an adapter of the wrong polarity would damage the circuit.  That is my first thought.

Al

[duck_arse]

some many years ago, I was given a DD-something, I think 3, but 1/8W resistors and much LSI and surface mount IS's. it had also fried it's supply protection and the 5V regulator. the alkaline battery would get hot, nothing would happen.

that pedal was d-e-d dead. converted it to a SQ150, sold it back to the owner.

[fender182g]

Is it possible that you at some time plugged in a power supply of the wrong polarity?.  If so, you could have burnt out the reverse polarity protection part of the circuit.  The Japanese pedals like that also require the older ACA Boss adapter, which put out over 12 volts, and the voltage is reduced by a couple of components to the regular 9+ volts.  However, if you plugged in the Boss PSA type adapter, that only supplies about 9 volts, the only thing that would happen is that the LED would not light up all the way, the pedal would still work to a certain extent, only an adapter of the wrong polarity would damage the circuit.  That is my first thought.

Al

Thankyou but i checked the polarity and it was correct also it says boss psa adapter only? 

[zombiwoof]

I didn't know any of the MIJ pedals used the PSA adapter, I thought they all used the ACA version.  I guess there were exceptions.  Actually, I really was just suggesting that you might have used the wrong polarity adapter by mistake at some point, but since you say you didn't, then that rules that out as the problem.  Something else must have burnt out or failed.  Oh well, just brainstorming here.
Al

Is it possible that you at some time plugged in a power supply of the wrong polarity?.  If so, you could have burnt out the reverse polarity protection part of the circuit.  The Japanese pedals like that also require the older ACA Boss adapter, which put out over 12 volts, and the voltage is reduced by a couple of components to the regular 9+ volts.  However, if you plugged in the Boss PSA type adapter, that only supplies about 9 volts, the only thing that would happen is that the LED would not light up all the way, the pedal would still work to a certain extent, only an adapter of the wrong polarity would damage the circuit.  That is my first thought.

Al

Thankyou but i checked the polarity and it was correct also it says boss psa adapter only? 

[duck_arse]

it seems this is your machine.
http://www.freeinfosociety.com/electronics/schematics/audio/pictures/bossdd2.png

you need to check the workingness of D6 and IC10. if there is not 5V from the output of IC10, the LSI chip and all the ram are likely gone.

[fender182g]

Thank you i will see what i can do.

[fender182g]

it seems this is your machine.
http://www.freeinfosociety.com/electronics/schematics/audio/pictures/bossdd2.png

you need to check the workingness of D6 and IC10. if there is not 5V from the output of IC10, the LSI chip and all the ram are likely gone.

duck_arse

i checked d6 and IC10 and on a battery and i was only getting 0.32 volts but when i plugged in the power supply it read at about 2 volts and after about 30 secs i started smelling that smell where the components are cooking  . D6 was also getting really hot and the other components were not. looking closer at d6 the solder joints have gone really dark and grey and it looks like a cold solder joint. here is a picture of the solder joint on d6.

[fender182g]

bump........

[duck_arse]

well, if you are REALLY lucky, like mark-hammer-lucky, your diode might just be shorting all the bad volts away from the softer parts downstream. really lucky. you have to pull the diode and test its diode-ness. it won't hurt to also find and pull the 5V reg, and TEST IT out of the pedal, for 5V out w/ 9 or so volts in. if the reg does turn out dead, you prolly well outta luck.

if the reg is good, replace it anyway **** check your pinouts ****, put in a new diode, and turn on, check for volts on the ic's see if it still lives.

but be prepared for the worst, and look around for something you might build into the empty shell.

[fender182g]

cheers,

Thanks for all your help!.