Boss DD3 diode replacement??

[ecc83]

pedal

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@]

Thankyou all

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!!

[Craigory]

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

Sorry to bring this topic up again, i did the same to mine. The diodes are the small black things labeled as D6 etc. correct? You are saying, just remove the diode D6 from the board and the pedal will work again. Can you also clarify the position of D6 because it's near the top of my pedal, not near the top of the pedal as you have suggested. Much thanks.
Craig

[howdood]

Hi there,
Yes - the diode labelled D6 on the board is the one which blows when you use the wrong PSU. I imagine its physical location might be different for DD2 / DD3.

I'd recommend removing whatever is marked as "D6" on your board, and seeing if the pedal starts working again. If it does, you've got the right diode.

I used my pedal for a couple of months with D6 missing, then bought a replacement zener diode on ebay for 60p as insurance for next time I forget the difference between power supplies. The pedal is still working fine though!

Good luck!
h.

[Craigory]

Hi there,
Yes - the diode labelled D6 on the board is the one which blows when you use the wrong PSU. I imagine its physical location might be different for DD2 / DD3.

I'd recommend removing whatever is marked as "D6" on your board, and seeing if the pedal starts working again. If it does, you've got the right diode.

I used my pedal for a couple of months with D6 missing, then bought a replacement zener diode on ebay for 60p as insurance for next time I forget the difference between power supplies. The pedal is still working fine though!

Good luck!
h.

I removed the small diode labeled D6 by melting the solder holding it, but no luck . Do i need to add solder to the empty location to complete the circuit or whatever? Thanks.

[howdood]

hmmm - strange. As I understand it, the diode is wired in so that, when it blows, it shorts out the whole circuit - that's how it works as a safety device, as it steps in to divert current before the chip gets fried.

If it's been removed, and the pedal is still not working, then (i) the "safety valve" diode in your particular pedal is not the D6, or (ii) something else has also blown.

A quick run through the various schematics should help here - the "safety" diode is whichever one is wired "the wrong way round" between live and earth - look for a diode that seems like it could not possibly function under normal operation; that's the one that blows under heavy / incorrect load.

Keep an eye out for bad solder joints on the PCB as well - sometimes just resoldering anything that looks less than perfect can bring a pedal back from the dead...

Good luck!
h.