Boss DD3 diode replacement??

[rabbit@]

I may have plugged my DD3 into the wrong adaptor or got the polarity wrong... and am getting nothing out of it, no red light ...no sound. Is there any hope in hell that I might be able to repair it with very little electrical knowledge??? perhaps, I was thinking, some genius may be able to supervise the surgery. It's the first DD3 model with the older board.

Thanks
Paul

[ecc83]

Hi Rabbit, I have just joined and am a v old electronics tech. I do not know what the DD3 consists of but if, as I suspect it is a digital delay you will have blown the processor most likely and since this will be !surface mount" technology, repair in any form is difficult.
I have a personal beef about rat powered gear that does not have polarity protection, it costs next to nowt and should be mandatory.
Sorry to give you bad news.
ecc83

[rabbit@]

Hi Rabbit, I have just joined and am a v old electronics tech. I do not know what the DD3 consists of but if, as I suspect it is a digital delay you will have blown the processor most likely and since this will be !surface mount" technology, repair in any form is difficult.
I have a personal beef about rat powered gear that does not have polarity protection, it costs next to nowt and should be mandatory.
Sorry to give you bad news.
ecc83


Hiya,

MMMM....The DD3 is the Boss Digital Delay no.3. Apparently , it can be repaired. I read a thread somewhere and it said that he had replaced the diode on the AC jack IN and had a result with that. he also said sometimes he has had to replace a chip ..in one case he replaced five !!!!! anyway he also mentioned that there is some sort of polarity protection there that will require a new thingymabob.....I was hoping he could guide me thru it but I can't get hold of the man...can't see me replacing the processor..sounds like I may as well go buy a new one.....which i am not going to do because..well I just can't face it knowing that there is a way to fix this bugger.
Thanks alot for the input.appreciate it.

[Luijo]

OK, next(or very close) to the DC power jack you'll find a small diode, the black cylinder with a white band close to one of it's edges. That's the most likely part to fail if you connected the power supply with inverted polarity.
This is a fairly generic rectifying diode and any one that fits in that space will do the trick. Mind you, this is NOT a zener diode, just a little rectifying diode to stop the pedal from getting any juice if connected to the wrong power supply.
If the diode is blown just remove it and bellow it there is a small drawing of a little rectangular box with a band close to one of it's edges, this is the way the new one is supposed to go in. This part is critical as it won't work or simply blow again if not done right.
Just pray the diode blew before the wrong polarity voltage got the chance to do any more damage.

[rabbit@]

OK, next(or very close) to the DC power jack you'll find a small diode, the black cylinder with a white band close to one of it's edges. That's the most likely part to fail if you connected the power supply with inverted polarity.
This is a fairly generic rectifying diode and any one that fits in that space will do the trick. Mind you, this is NOT a zener diode, just a little rectifying diode to stop the pedal from getting any juice if connected to the wrong power supply.
If the diode is blown just remove it and bellow it there is a small drawing of a little rectangular box with a band close to one of it's edges, this is the way the new one is supposed to go in. This part is critical as it won't work or simply blow again if not done right.
Just pray the diode blew before the wrong polarity voltage got the chance to do any more damage.

Hey Luijo,

Wonderful to hear from you!! You sound like my saviour.
Pardon my ignorance here. Am trying to locate the diode you are refering to.
May I send you an e-mail pic of the board and you could check it out and direct me to the right one ??

[Luijo]

No probs with the email, just remember to send the pic of the component side of the board.
I don't know if you can access my email addy from here (must be somewhere in my profile), if not just let me know. Sorry, not fond of posting addresses, you know, spam knocking at your door.;)
You can try posting the pic here too. Just let me know what you prefer.

[rabbit@]

No probs with the email, just remember to send the pic of the component side of the board.
I don't know if you can access my email addy from here (must be somewhere in my profile), if not just let me know. Sorry, not fond of posting addresses, you know, spam knocking at your door.;)
You can try posting the pic here too. Just let me know what you prefer.


Excellent! have sent you an e-mail. can't get the pics up here.

[Luijo]

No email from you yet...strange.:confused:

[rabbit@]

No email from you yet...strange.:confused:

Have tried two addresses that I found and have had both returned .
one at 'f......ttle' and another one at '...dog'.
Can't get the pics up on the site either...bare with me ..I'm on the case....
I sent you my e-mail adress ,but I guess you did'nt get that either.

here's mine: rabbitbreth@yahoo.com .could you get in touch with me there and I will send the pics right back. Thanks for your patience.

Paul

[Enzo]

You sure that's not a zener? When the Boss pedals I have encountered were fed reverse power, the diode shorted alright, but it was an 11v zener. That kept excess voltage from the circuit, but in reverse voltage conditions, it was just a diode across the supply, so it shorted the supply, thus protecting the pedal, but at a cost of the diode's life.

My DD2/3 drawings show it as a zener.

Often as not, a new diode replacing the shorted one, and the pedal is OK.

[Luijo]

Enzo, I might be wrong about the diode NOT being a zener, thanks for the heads up.
I've repeared a few of those pedals a long time ago and it was always the same diode, blown by the use of the wrong power supply. Maybe since you have the schem at hand you could tell rabbit the exact id of that part on the board. Could you please email me a copy of that schem too, if you're so kind?
Rabbit, I don't an addy at any of the places you mentioned, but I'll send you an email anyway. As an advice, don't post your email address so openly on the net, you're making yourself vulnerable to spam.

[ecc83]

Hi Enzo. I have encountered the "zener diode" problem in many and various bits of gear. I am at a loss to know why designers do it! Sure the diode blows up on reversed supply but is then O/C and does not protect the circuit. If there is a low Ohm, fusible feed resistor the that would make some sense, but not much. I do not have access to Bosss circuits and their site does not seem to want non US residents to register(it will not recognise my UK phone no).
I was a bit suprised when I first read of a burned out diode since a series (the logical way to give polarity protection) 1N4002 would be practically indestructable in this posistion.
Sorry I was a bit pessimistic in my first post but these things CAN waste your life!
I could send diodes, zener or otherwise plus resistors but Diety knows how long they would take to arrive.
Merry Christmas to you all
Dave.

[rabbit@]

Hi Enzo. I have encountered the "zener diode" problem in many and various bits of gear. I am at a loss to know why designers do it! Sure the diode blows up on reversed supply but is then O/C and does not protect the circuit. If there is a low Ohm, fusible feed resistor the that would make some sense, but not much. I do not have access to Bosss circuits and their site does not seem to want non US residents to register(it will not recognise my UK phone no).
I was a bit suprised when I first read of a burned out diode since a series (the logical way to give polarity protection) 1N4002 would be practically indestructable in this posistion.
Sorry I was a bit pessimistic in my first post but these things CAN waste your life!
I could send diodes, zener or otherwise plus resistors but Diety knows how long they would take to arrive.
Merry Christmas to you all
Dave.

Thanks for all the input fella's. I'm glad you all know what you are talking about because it's looking more like Greek to me as the days go by.
Anyway I am all ears and will fumble my way thru this as best as I can.
I have a schematic which I am trying to upload....stay tuned and Merry Xmas too.

[rabbit@]

Here's the link for the Schematic.



http://www.8bitsindgenug.net/boss_dd2.png

[Enzo]

That is exactly the schematic I have - that is an 11v zener.

They do it for a couple reasons. One is that it limits the input voltage. That 9v battery will not trigger it, but the average adaptor might. Too high voltage can fry things. Sure it is brute force, but it works.

Also, it is my experience that they usually fail shorted, so in the case of reverse voltage, that short prevents the voltage from continuing into the pedal. If it fails open, then of course no such protection. If replacing the diode restores operation though, then it did its job.

Series diodes would protect against reverse, but not over voltage. Plus there would be the half volt loss through the diode. A resistor would be worse, it would waste current, drop voltage, and degrade supply regulation. I don't know that you could fuse something like this against reverse volts. The current to damage the chips I have to think is far lower than it is to actually burn them up. The chip failing would be the draw that blows the fuse anyway, so a fuse would be after the fact.

If you replace the diode with a plain old diode, it still protects against reverse in the same way, but it offers zero defense against over volts.

It should be a plain old 1 watt zener, 11 volts. If you don't have one, I suspect a plain old 12v zener will work as well. I have a sneaky feeling a few 12v zeners have found their way into some of my repairs as an expedient. The extra volt only comes up with excess adaptor voltage anyway. Remember, the caps in this thing are only 16 volt, so we don't want an 18v adaptor burning all the caps up

[ecc83]

Hi Enzo,
I did know why they did it, it was a throw away remark. There is a 7805 reg' feeding the main chip which can cope with up to 30v.Since, if the 11v zener it turned on by overvolts it will appear as a s/c and there is no form of current limit, destruction of the diode and/or power supply is almost certain!
A series diode on the dc supply board, in the external supply only would not rob battery vollts.
Most power supplies have about 2200mfd of res'cap and this will dump enough current through a 0.125 1Ohm resistor to burn it out.
The 7805 takes care of 5v regulation and there is adequate decoupling for the rest of the circuitry including C23 decoupling the 1/2vcc supply. Most modern I.C'S have excellent power supply rejection.
The purpose of D6 is to protect against accidental battery connection which it will probably survive, though this is by no means certain if a sealed lead acid type is used!
I am in the process of prepairing an article on the subject of external PSU's (known as wall rats over here) and so the shortcomings of designers are a bit of a hobby horse at the mo'
Rock on! ecc83

[rabbit@]

OK. thanks alot Enzo. Can't get going until I order some replacements .No electrical component retailers out here in the Pyrenees.
Appreciate all your time. Will post my adventures as soon as I get the goodies thru the post.

Later!

[rabbit@]

My thoughts exactly ecc83!!!!!!

[rabbit@]

Looks like my DD-3 is done for. I removed the D6 zener and got the light on and the clean signal thru 'direct out' ...however where there is supposed to be a processed signal coming thru 'output' , there is just another clean un-delayed signal which means that I have gone as far as I can without replacing some of the vital organs in the pedal. May have another crack at it some other time, and some other place....preferably with a electrical component retailer in the vicinity.
Just want to say a big thanks to you all for being so generous with your time and knowledge. Extra thanks to ecc83!

Cheers
Rabbit@

[howdood]

Hi there,
first - many thanks for this thread - it meant I was able to get my DD-2 working again after I plugged an 18v power adapter into it by accident at the gig last night. I'll use the money I now don't have to spend on a new delay pedal drinking your health at the jazz festival in Cork this weekend.

second - in case anyone comes across this thread in future, the diode which is set to blow with the wrong power supply is labelled as D6 on the schematic and on the circuit board itself. I worked that out because it's the only diode wired in the 'wrong way round'.

It's nowhere near the AC jack, though - it's on the main board, at the bottom. To get the pedal working again, you don't need to replace it - just remove it from the board and that should be enough to bring the pedal back to life. Of course, if you don't replace it you run the risk of frying the chip next time you plug your beloved DD2/3 into the mains by accident!

Right - now I know that, I think I might start lurking on eBay for 'broken' boss pedals to fix :)

[rabbit@]

Hey there Howdood!!

Well done on getting your pedal up and running. This forum is excellent aint it.
Nice folk ready to dive in and lend a hand.
Even though I never got my DD-3 going I really enjoyed the education. Have just got back to France from the UK having spent some money in Maplins on new soldering gear and component lucky packs. I have a few more little projects lined up and am having trouble accepting the fact that my DD-3 is kaput...especially after your post.
Have my eye on the latest 'Space Echo' which should ease the pain somewhat I hope.

Hope you had a good time at the Jazz fest. My girlfriend was over there last weekend. She has friends just outside Cork.

Here's a Guinness to Delayed Ecstacy!!