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Jam
Copper Member
United Kingdom
1 Posts |
 Posted - 06/08/2008 : 22:59:50
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Hi to all on the forum!
I was wondering if I could please have some help on the following issue:
I have a Boss SD-1 which has stopped working.
Initially it would pass a signal when in bypass mode but nothing when switched on.
On opening it up I saw that diode D1 was burnt and cracked in 2! I couldn't read the part number but replaced it with a 1N4001 aligned as before (grey stripe nearer R18).
The connections seem OK but now no signal at all is passed to the amp from the pedal on either bypass or on mode!
I was wondering if anyone could please suggest how to get the pedal working?
My thought is that maybe too much power blew the diode and possibly fried the amplifier chip too?
Thanks
J |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 06/08/2008 : 23:29:45
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Hello and welcome to the forum!!
The diode you have replaced is an 11V zener diode. A 1N4001 won't do the same job, but it shouldn't do any harm either (as long as it is in the correct orientation - stripe toward R18)...
You can remove the diode completely and use a battery to test the pedal - be VERY careful and don't accidentally touch the battery to the terminals the wroing way around!
If it works without D1, the pedal is OK, and you will need to buy a 1 Watt 11V (or 12V) zener to replace D1.
If it doesn't work without D1, then the opamp is almost certainly dead - with D1 split in half, I'm betting the opamp is toast too.
Schematic is here:
http://www.godiksennet.com/images/sch/SD1PG2.JPG |
Edited by - Laurie on 06/08/2008 23:30:48 |
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zentropa
Gold Member
USA
837 Posts |
Posted - 06/08/2008 : 23:50:01
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Jam:
it's kind of tough to dig up an 11v without a lot of effort, but 12v should be fairly common and cheap.
i bought a couple to replace a fried one a while back... i have one left and i'll try to dig up a number for it.
JRC4558D/DD or equivalent are fairly cheap, so even if that's cooked it shouldn't set you back more than $1 to replace it.
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 06/09/2008 : 05:02:54
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Hi Jam
First of all, Welcome to the Forum from Australia.
a 12V 1 Watt zener will be Ok
You were unlucky that it slip, & went open circuit, this would have allowed all the rev. volts to hit the Op-Amp.
Remember:
Dr. Bob's Theorem Number 2506, Op-Amps HATE Reversed VOLTAGES... 
Taken from a similar & recent problem with DD-3.
http://www.bossarea.com/forum/topic.asp?TOPIC_ID=4599&whichpage=1
Check any electro's as well, they may have been damaged, or worse slightly damaged.
Good Luck.
Please keep us informed of your progress, with the repair.
Regards Dr. Bob |
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DeFrag
Moderator
USA
3409 Posts |
Posted - 06/09/2008 : 08:14:05
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Welcome to Bossarea Jam!  |
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Topic |
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Boss SD-1 not passing audio!
