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papa_lazerous
Copper Member
United Kingdom
4 Posts |
 Posted - 04/01/2008 : 21:55:04
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Hi all, I'm afraid to say I am new here and its got to be a quetion with my first post. I am already into stompboxes in a big way spend many an hour over at DIYSB for those of you who frequent Arons site.
Anyway I got a DD-3 today in the post from ebay, listed as working sometimes, Pah! complete lies
Its a version 1 board, after applying power it takes about 10 seconds before the stompswithc will work and the RED bypass LEd will stay latched I have been led to believe this is normal on this pedal. before that there is no LEd for a few seconds then after that you stomp and it lights but doesnt latch.
What is actually happening...... Well at the output I am getting a totally clean signal regardless of bypass and same on direct out.
I am not asking for anyone to wave a magic wand or anything I am more than capable of trying to figure it out if only I can find a schematic  I have googled a fair bit and not come up with anything as yet, figured with the information on this site (have used it as a reference a few times) that someone here may have some ideas about where to find one or have any tips or info on fault finding this pedal. I am thinking that my first port of call will be checking the actual bypass circuit and make sure its actually working regardless of the LED state, I have a bad feeling the processor chip has gone south in which case I dont know if they can be sourced??
Any help for the newb greatfully appreciated, and I am sure once I learn the ropes round here I can help out on other matters |
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ChristoMephisto
Platinum Member
Canada
1288 Posts |
Posted - 04/01/2008 : 22:08:51
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Hey hey welcome to the forum
the early dd3s were the same as the dd2
from the sounds of things, cap or two has died, or near death
as it takes a bit to charge itself
good luck |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 04/02/2008 : 08:36:28
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Hi papa_lazerous
Firstly, welcome to the forum from Australia.
If your DD-3 is an early one, it will have the long DIL processor IC across the width of the pedal.
It is most likely that it's the 5V 100mA regulator (78L05) or associated components that have been damaged by, possibly some reverse polarity,
Look around the area of the 78L05.
the DD-2-3 all have that delayed turn on effect, that makes them appear to be faulty at first.
Look at the protection diode as well, I think it was D4 on the DD-2's
Here is a link to some schematics that will probably help you out.
scroll down the list a bit .... 
http://www.freeinfosociety.com/electronics/schempage.php?cat=1
Hope this helps & good luck.
Keep us informed of your progress.
Regards Dr. Bob |
Edited by - Dr. Bob on 04/02/2008 08:37:27 |
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papa_lazerous
Copper Member
United Kingdom
4 Posts |
Posted - 04/02/2008 : 20:24:23
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Thanks Dr bob for your reply and warm welcome,
There are no issues with the protection diodes or 5v Reg on the pedal, after looking at the schematic at the bottom left it says there is a mute for 5seconds from power on.
also you are correct about the large DIL processor chip, it is one fo those
If I plug the effect in I get sound out - meaning with the effect off (bypassed) I get a signal through fine no problems
If I stomp and the red light comes on and play the guitar with the amp turned up I can hear a very very very faint delay although the dry volume is perfect and at the volume you would expect. I am looking at the schem but it is a little complex for what I am used to. I was wondering if there is either a problem with the expanding side of the compander chip or I think there is a FET near where the wet and dry get mixed possibly near there. but I am poking around in the dark right now.
Was considering replacing caps as one may have dried out and be not letting signal through, also a shot in the dark |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 04/02/2008 : 20:34:15
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Hi papa l!
Can you test for audio in the circuit? Looking at the circuite for the DD-2, is there signal at IC1 pin 1? How about IC1 pin 2? How about either side of R13?
Sounds like it might be IC1 or Q5 potentially? |
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papa_lazerous
Copper Member
United Kingdom
4 Posts |
Posted - 04/02/2008 : 20:44:54
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I was originally wondering about Q5 although for me to have a dry output it seems to me that this FET must be working as it and R13 recieve a dry signal....
IC1 is curious though IC1a should see the wet and dry mix at pin 2. I have a scope and audio probe so there is no problem checking this.
I do think that this opamp must be funtioning to some degree though as it wouldnt pass the dry signal if not it appears logically to me that the signal is weaker before this.
I was also considering Q8 as this is the FET that controls the wet signal from the expanding side of the compander. There is also that the compander is not expanding..... I dont know how to test this part very well though.
I am at work for 10 more hours (darn night shift) but will be able to check tomorrow
thanks for the input |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 04/02/2008 : 21:24:58
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Quite right. I'm looking at the circuit for a DD-2 (which I believe is equivalent to your DD-3 from the thread) and IC1a only is in the effected circuit (not Q5 my mistake) - and your reasoning is sound - you have an output, so it's probably OK. So, check for signal at both sides of C29, C28, and C13 and let us know what you find there - that will point us in the next direction...
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Edited by - Laurie on 04/02/2008 21:28:20 |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 04/03/2008 : 08:37:59
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Hi papa_lazerous
These pedals are getting a bit old in the tooth & they are very complex for their place in the Boss pedals Time-Line.
Get out your best magnifier & a good light, & start looking for dry joints & anything that looks a bit suspicious.
Look for wires that may have come loose, this was the main issue with one of the OD-1's, the solder joints where the wires connect to the board had become brittle..
Also, if there was even a chance that the pedal suffered any reversed voltage, even for a short time, start to suspect the op-amps.
They absolutely hate being driven by rev. volts.
Once you gey out your CRO & Sig.Gen, it should make fault finding a bit simpler.
Yes the schematic is very complex, just break it down into manageable chunks.
Remember not to run too much signal into the input, keep it around 50 to 200mV and more typically about 100mV.
Do the steps that Laurie outlined, I see what you find.
you can always try racing the signal from output back to input.
You have one of the better DD-3's.
When they changed the IC, it made it a bit more synthetic & brittle.
Good luck & keep us up to date.
Regards Dr. Bob |
Edited by - Dr. Bob on 04/03/2008 08:45:17 |
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papa_lazerous
Copper Member
United Kingdom
4 Posts |
Posted - 04/06/2008 : 21:55:49
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Right I finally got an hour to sit down and look at what was going on with this pedal.........
Looking at the schem for reference, I rigged up the pedal with a signal off 100mv going through and an audio probe so I would be able to hear where teh signal was, sometimes simpler than the scope.
Looking at Q8 I get a very very weak signal both sides ie at C28 & C29 side. This is the same weakness experienced at the output. So I went a little further. the the NE570 compander chip. I have linked to the datasheet below. On PIN 10 I should get Output 2 there is only a faint signal there, so I suspected the cheap so I went to the other side of the chip........ As one side compresses and the other side is used to expand. And at PIN 7 Which is Output 1 I get a strong signal...
So I figure I would probe the input pins, makes sense after all.
I get s signal at pins 14 and 15 thats stronger than the outer.
I will make one observation before we get lost here the section I am talking about is marked Expander its not its a compressor. As I understand it you get expansion first it goes through the effect then it picks up all the noise from the effect then it gets compressed to reduce sound to original level and noise to a minimum....
So I have a poor sound out of PIN 10 of compander but I fear its becasue the signal going in is also too poor.
Ideas appreciated getting stuck lol
http://www.ortodoxism.ro/datasheets/philips/SA571.pdf |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 04/21/2008 : 20:31:48
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papa_l ... I just noticed we hadn't done any more on this for you. Have you found the problem? Any further info available from your fault-finding?
Regards,
Laurie |
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FRANZONI
Double Platinum Member
Ireland
3543 Posts |
Posted - 04/21/2008 : 22:35:31
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Can i ask if your using a boss power supply or another make.??.the reason is you guys are all well up on the tech side of things but i have a couple of DD-3's and one time when was stuck i ran them off a zoom adapter,all my other boss pedals..i.e. CH-1,DS-1,OD-2 etc... worked ok but the DD3 came on with the led as normal but no effect....?? thats why i always use the boss adapter..i was always wary of other makes in case they did damage or just wouldn't work properly.... |
Edited by - FRANZONI on 04/21/2008 22:36:00 |
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PacoPicoPiedra
Copper Member
United Kingdom
16 Posts |
Posted - 04/22/2008 : 18:48:46
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Hi people,
I've also got a dead dd-2 which as I understand it is nearly identical to the ver.1 dd-3, it passes the dry signal when its on and off and the led turns on and off as it should in all the modes, just not getting any wet signal. I've tested the power regulator and i'm only getting a few mA at the output. I would just change it but this is a freshly installed one and I got the same thing with the last one so I'm thinking something else must be wrong for it to keep happening. All else I can say is that the regulator and protection diode get seriously hot whenever the pedal's plugged in, although the diode could just be heating up from the radiated heat from the regulator. been trying to tackle this myself for quite a while now but i basically don't have much of a clue what i'm doing so i reckon its time to give in and call on your expertise.
cheers
p.s apologies if i should be starting a new thread, there already seems to be a lot on here with similar symptoms |
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alfiollett
Copper Member
Norway
2 Posts |
Posted - 04/22/2008 : 19:59:35
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I had the same problem with my dsd-2, but i found out that if i bypassed resistor r44 (the one between pin 14 and 15 on the ne570) it works as it should, don't know why, the resistor is not harmed. But it works, but i haven't tried it for more than a couple of hours.
Hope it helps, if anyone knows why this helped at all please tell me!
By the way, if someone needs the schematics for the dsd-2 tell me and I'll e-mail it to you.
Lots of love,
alf |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 04/23/2008 : 09:53:13
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Hi PacoPicoPiedra
Hi alfiollett
Welcome to the forum from Australia.
PacoPicoPiedra
The 78l05 regulator should not be getting hot, unless you are running a non-boss type adapter into the DD-2
Some non regulated 9V adapters can be as hi as 12V, then the 78L05 would be getting hot trying to dissipate the extra voltage.
if it's not an over voltage plug pack adapter.
Have you checked that the protection zener isn't partially shorted,
What caused your DD-2 to fail?
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Hi alfiollett
As for the DSD-2 Schematics.
Do you have a link, that you can post to the:
Modifications and Technical Issues / Pedal schematics -- LINKS ONLY
http://www.bossarea.com/forum/topic.asp?TOPIC_ID=4276
Regards Dr. Bob |
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alfiollett
Copper Member
Norway
2 Posts |
Posted - 04/23/2008 : 14:53:53
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| sorry, i have no place to host it, so i have no link. |
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PacoPicoPiedra
Copper Member
United Kingdom
16 Posts |
Posted - 04/23/2008 : 18:12:09
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hi dr. bob, I'm running the dd-2 off an unregulated korg 9v supply, it reads about 11v if i just use the multimeter on it, but I have been running this and several other boss pedals off these adaptors for ages with no problems. As to what caused it to fail, well long story short, I opened it up to generally tidy up my wiring after installing a jack for an expression pedal (which was working great at the time) and in the process, most of the wires to the power jack got loose, so after staring at the schematic for a while I worked out where everything had to go and put it all back as it should've been and it was after this that I couldn't get any wet out. I did think at some point while putting it back together I may have reversed the polarity and killed the protection diode so that got replaced but to no avail.
I would point out that the diode I replaced it with was a BZV85C 11V from http://www.maplin.co.uk/module.aspx?ModuleNo=19090&doy=23m4
this was basically because as anyone in Britain knows, maplin pretty much have the monopoly on components and it was the closest thing they have.
Looking at the specs I was pretty sure it would do the job just as well, but if not it'll be my stupidity killing my pedals again  |
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Topic |
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DD-3 problems
