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natthu
Gold Member
Australia
756 Posts |
 Posted - 10/01/2009 : 16:52:26
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I accidentally plugged it into the wrong socket on my power brick.
Now it smells like sizzled electronics. I hate that smell.
I am a sad mango 
I checked out the damage and it looks like a component right where the power hits the board is the only casualty 'D4(11)'...
Hopefully it should be an easy fix. It's a bit of a shame because it was such a clean board. Since it's going to be non-original now maybe I'll do the mod that makes it PSA instead of ACA... Is that possible for a DM-2?
I'm off to put tape over that socket on my power brick, then I'm going to cry myself to sleep (ok, so it's not that bad. I'm just being melodramatic  ). |
Edited by - natthu on 02/10/2010 14:03:28 |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 10/01/2009 : 17:04:09
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D4 is an 11V 1W zener. Replace it with a 12V 1W zener (11V zeners are impossible to find). it is designed to fail if something like that happens, so all should be well.
Remove and jumper D1 and R2 for the PSA mod.
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zerksies
Double Platinum Member
USA
3406 Posts |
Posted - 10/01/2009 : 18:35:52
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| hope that is a simple fix |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 10/02/2009 : 07:35:58
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Ouch!
Luckily it's not too difficult a fix.
Regards Dr. Bob  |
Edited by - Dr. Bob on 10/02/2009 07:42:54 |
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natthu
Gold Member
Australia
756 Posts |
Posted - 10/02/2009 : 09:15:57
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Thanks Guys. Special thanks to Laurie for that info  . Very helpful, Cheers.
I'll let you know how the fix goes. Might have to wait a while as I'm off on holidays soon  |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 10/02/2009 : 14:50:59
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quote:
Originally posted by natthu
Thanks Guys. Special thanks to Laurie for that info . Very helpful, Cheers.
I'll let you know how the fix goes. Might have to wait a while as I'm off on holidays soon
It is possible to use the pedal without D4 in circuit (just remove it), but any over-voltage or reverse voltage that might happen while D4 is out will kill it for sure.
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natthu
Gold Member
Australia
756 Posts |
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Laurie
Double Platinum Member
Canada
4854 Posts |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 10/03/2009 : 17:48:41
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quote:
Originally posted by Laurie
quote:
Originally posted by natthu
Hey Laurie, Is this what I'm looking for?
http://jaycar.com.au/productView.asp?ID=ZR1411&keywords=zener&form=KEYWORD
I don't think it's worth risking not having D4 (considering I've already fried it once).
Good old Jaycar... yeah that's it.
Hi natthu
I 100% concur with Laurie.
I have used those when I am on the road, and one other time,
when my bulk supply ran out.
Things to consider when repairing your DM-2-other pedals:
Can I suggest that you leave a small air gap under the body of the
zener when you refit it back to the DM-2.
By that I mean lift if off the PCB by about 3mm to 6mm.
This will stop the PCB from burning up, & turning into charcoal under the zener diode,
should you ever accidentally plug it into the incorrect supply or voltage.
The extra few "mm" of lead also acts a a small heatsink,
perhaps giving you a few milliseconds extra before the zener
goes to the big smokestack in the sky.
Can I ask you to measure the burned out zener?
It should have failed as a "Short Circuit" hence the reason it burned up.
But if left for long enough, it may have failed as an "Open circuit"
In this case you may have caused some other damage,
This could be typically opamps, & maybe a few electrolytic caps across the 9V rail.
Opamps absolutely hate reversed voltages.
I hope for your case (as is generally typical of such failures of zeners),
that it failed as a short circuit.
Good luck
Regards Dr. Bob
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natthu
Gold Member
Australia
756 Posts |
Posted - 10/04/2009 : 10:23:58
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I got myself an 11V 1W zener from jaycar. I might have a go at the repair tomorrow, it's a bank/public holiday here in SA and all my friends are going to a Festival (dancey music - not really my scene).
Laurie - Yeah Jaycar is my friend. Unfortunately they always look disappointed when they see what I'm buying (e.g. a 55c diode)
Dr. Bob - I will tackle that request for you (I will even mail you the blown zener if you wanted to check it out yourself). Thanks for the tip re: raising the diode off the board, it's simple and makes sense but I wouldn't have thought of it. Cheers.
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Edited by - natthu on 10/04/2009 10:24:36 |
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natthu
Gold Member
Australia
756 Posts |
Posted - 02/10/2010 : 11:14:36
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HURRAH!!!!
So I finally got around to fixing my DM-2. It's been an ongoing saga.
I actually lost the first replacement diode I bought. I put it in a safe place so I wouldn't lose it. Wherever that place is, it seems to be very secure because I have not seen it since.
I had to go back down to Jaycar and spend another 55c to get another diode.
I tested my DM-2 with some other pedals in a 9V chain and it works perfectly. I decided not to do the PSA mod after all.
Laurie - Cheers again for the help, it's much appreciated.
Dr Bob - the blown out diode measures 4mm long by 2mm diameter (to the best of my ability to measure such small things)... I hope that is still useful to you - sorry about the wait. I also used your tip of raising the diode off the PCB a bit. Cheers for that.
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Fixed my DM-2
