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MullyFX
Gold Member
Germany
753 Posts |
 Posted - 05/16/2008 : 18:11:26
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didn't wanna polute the pedal internals thread... so here's my question....
what is this ? and does my DM-2 sound so good because of this?
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 05/16/2008 : 18:26:06
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Hi MullyFX
It appears to be from pin 3 of the 3102 Clock driver IC
that feeds the BBD.
It also looks like the is a track cut or damage to the track.
Just under the the diode at pin 3. (looks like the Anode)
Are you able to get a better Cloe-up shot of just this area?
It difficult to see, where the other end of the diode connects to.
That's be best I an do at 2:20am MullyFX.
Hopefully some of the other guys will pitch in a& offer their help as well.
I see Laurie is on line.
Thanks for being considerate posting this to a separate thread.
I have update your DM-2 into the Index.
Regards & good night guys Dr. Bob
PS - The soldering on that diode looks very poor as well.
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 05/16/2008 : 19:09:59
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Veeeery interesting! Need a closer-upper-picture though please  |
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MullyFX
Gold Member
Germany
753 Posts |
Posted - 05/16/2008 : 19:10:38
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yup the PCB is damaged.... bummer... and I thought it was a good deal (at least not a bad one - as it starts to seem now)
I take better pictures as soon as my camera is working again.... gotta recharge... doesn't run off a Onespot the bugger
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MullyFX
Gold Member
Germany
753 Posts |
Posted - 05/16/2008 : 19:12:00
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quote:
Originally posted by Laurie
Veeeery interesting! Need a closer-upper-picture though please
gimme an hour or two and I will post some more pics |
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MullyFX
Gold Member
Germany
753 Posts |
Posted - 05/16/2008 : 19:15:06
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no wait here's one
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 05/16/2008 : 20:23:33
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So pin 3 of the 3102 is through a diode to ground, instead of direct to ground. Interrrrrsting.
The net effect is to "lift" the chip 0.7 volts above ground. I have NO idea why they might have thought that was a good idea. Dr. Bob might have seen it before?
Do you know how it sounds compared to other DM-2 pedals?
It doesn't look like there is any real harm done - easy to put back to original if you wanted to.
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Edited by - Laurie on 05/16/2008 20:24:04 |
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MullyFX
Gold Member
Germany
753 Posts |
Posted - 05/16/2008 : 21:02:55
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well I only know this DM-2 and it sounds great. and better than my other analog delay which is the Ibanez AD99.
so soundwise I'm not worried really. the thing that bothers me is the damage done to the PCB.... could that cause any failure in the future - is there a way to fix this? |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 05/16/2008 : 21:31:26
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As far as I can tell from the picture, the soldering on that diode is OK, and the track won't suffer any more damage/dererioration unless you do some more soldering. The damage you can see (the "yellow" circuit board showing through) was done intentionally to break the circuit to install the diode - unless more damage is done intentionally, it shouldn't get any worse.
If you are going to leave it the way it is, then just put the lid back on and don't worry.
What I'm really interested in is if someone can explain this mod? Is it a known mod? Does it really make a diference...?
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Edited by - Laurie on 05/16/2008 21:33:51 |
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MullyFX
Gold Member
Germany
753 Posts |
Posted - 05/16/2008 : 22:20:32
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quote:
Originally posted by Laurie
As far as I can tell from the picture, the soldering on that diode is OK, and the track won't suffer any more damage/dererioration unless you do some more soldering. The damage you can see (the "yellow" circuit board showing through) was done intentionally to break the circuit to install the diode - unless more damage is done intentionally, it shouldn't get any worse.
If you are going to leave it the way it is, then just put the lid back on and don't worry.
What I'm really interested in is if someone can explain this mod? Is it a known mod? Does it really make a diference...?
thanks Laurie,
that's good news
I love the way it sounds (if the mod changes something or not) and don't plan on doing any more mods.
cheers,
mully |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 05/17/2008 : 04:32:30
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Hi MullyFX, Laurie & guys
To test whether the mod really makes any difference.
just clip/solder a jumper wire across the diode, & it will temp. put the pedal back to it's original design.
I can't see it doing any damage to the DM-2
If you're really pedantic.
turn off the pedal(unplug the input) between, the link & the diode mode.
Listen for any changes.
or even temp. wire a small switch across the diode & you can do an AB test.
If you do, please let us know, what you hear-find.
I have not seen this mod. that lifts pin 3 0.6-0.7V above GND.
Any chance you can ask the person you bought the pedal from?
Regards Dr. Bob
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MullyFX
Gold Member
Germany
753 Posts |
Posted - 05/17/2008 : 17:57:14
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Well I sent him an email.... but I doubt he knows anything about it he bought it used as well (or he says he did)
will let you know when / if he gets back to me
I don't see myself soldering around though.... maybe when I score a minty DM-2 (the man has dreams) I will.... |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 05/17/2008 : 18:06:19
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| I have a DM-2 coming this week ("road worn"). I'm half contemplating socketing the IC and putting an AB switch in to see what the difference is. Will let you know if I actually decide to do that... |
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ChristoMephisto
Platinum Member
Canada
1288 Posts |
Posted - 05/17/2008 : 19:40:26
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I havn't a clue what that would be for, jumpering the pin3 of the bbd driver to ground with a 4148 diode.
OK, wait, think i found something....
Look at the pcb layout of the dm2 at http://www.godiksennet.com/default.asp?main=Schematics
where's your D5 diode coming off of pin1 of the bbd driver like in the schems? You got a second gen dm2 with the mn3102 bbd driver.
found some pinouts of the mn3101 and 3102 next to each other and discovered that pins 1 and 3 are reversed. In the 3101, pin 1 is the ground, and pin 3 is Vdd. On the 3102, its reversed.
My guess is someone else noticed this and attempted a original DM2 mod. Still not sure what this does tho...tried to raise the 'H' Level output from .7mA to about 1.5 maybe? The 3101 has 1.5mA output
Dr.Bob, its the weekend, why you making me think? |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 05/18/2008 : 16:24:36
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quote:
Originally posted by ChristoMephisto
I havn't a clue what that would be for, jumpering the pin3 of the bbd driver to ground with a 4148 diode.
OK, wait, think i found something....
Look at the pcb layout of the dm2 at http://www.godiksennet.com/default.asp?main=Schematics
where's your D5 diode coming off of pin1 of the bbd driver like in the schems? You got a second gen dm2 with the mn3102 bbd driver.
found some pinouts of the mn3101 and 3102 next to each other and discovered that pins 1 and 3 are reversed. In the 3101, pin 1 is the ground, and pin 3 is Vdd. On the 3102, its reversed.
My guess is someone else noticed this and attempted a original DM2 mod. Still not sure what this does tho...tried to raise the 'H' Level output from .7mA to about 1.5 maybe? The 3101 has 1.5mA output
Dr.Bob, its the weekend, why you making me think?
Hi Christo
Really good spot, I knew your younger eyes would find something.
But after looking at it for the past afternoon, the diode on MullyFX's Modded DM-2 is
Anode on the Clock IC
Where D5 on the Schematic for the DM-2 at the above link, is
Cathode on the Clock IC.
But I think we're on the right track...
Regards Dr. Bob |
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MullyFX
Gold Member
Germany
753 Posts |
Posted - 05/18/2008 : 16:37:12
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if you need any more pictures just say so :)
this is really interesting... like watching Sherlock Holmes - hehe (not that I like to watch Sherlock Holmes but you know what I mean) |
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Topic |
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DM-2 Diode Mod
