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I just fried my Boss SD-1. Help?

aerochris

Member
Messages
34
I just got a Boss SD-1 and plugged it into the charger for my Line 6 Floor Pod. Apparently, that was a bad idea. Now there is no sound coming out of the SD-1 and it smells funny. I took the back off and D1 is burnt in two on the circuit board. Does anyone know what size D1 is? It's in the corner by R22 and R27. I looked at a schematic but it didn't have labels for the resistors, capacitors, etc.

Any help would really be appreciated.

Thanks,

Chris
 
Messages
6,140
Just install an LED or any 9v diode. Will do the same job, just get the polarity right. I had the same issue - I lent my brother my blues driver, and he was suprised that his POD adapter didn't work.

Whoda thunk?
 

Stormbringer

Member
Messages
1,302
D1 in an SD-1 is a 1N4001 and like the previous poster said, just replace it with any 9v diode or a led, respecting the polarity.
 

jfromel

Member
Messages
1,127
Putting an LED in there will do nothing more than murder a perfectly good little light. Replace D1 with a 1n4001 available at radio shack. If yours is an older SD-1 with D3 and R31 you should replace those as well, or jump them to make the pedal PSA capatible. It's not a bad idea to replace the caps on the power rail C17 100uf 16v (recommend 25v or higher) and C11 47uf 5.3v (recommend 16v or higher). Mind your polarity!!!
 

aerochris

Member
Messages
34
Thanks for the replies. Lots of people have mentioned to make sure the polarity is correct. How do I make sure something isn't in backward? Obviously, I am new to this....
 

Briggs

Member
Messages
78
The line around the body denotes negative. Make sure that points towards ground. It's a built in protection diode to stop the rest of the circuit from frying when you plug in reverse power (Stick + at - and vice versa).
 

aerochris

Member
Messages
34
Okay. I replaced the diode and the pedal powers up now but there is no sound coming out of it. Even when the pedal is off no sound will go through it. Everything else on the board looks fine. What could be causing this?

Thanks!
 

stinkfoot

Member
Messages
6,132
The common suspects when the wrong adapter has been used are the polarity protection diode (D1 - usually a 1N4001, but in the older SD-1's it's an 11v zener) and the main filter capacitor (C17 in the SD-1). Both tend to fail, shorting the power out completely (which is good, since it protects the more delicate circuits in the pedal from the reverse-voltage).

However, since the polarity protection diode blew in two parts (rather than just short out), it's quite possible that it failed to protect the circuit from the AC voltage. If that is the case, it can be anything - you may have to replace the op-amp and possibly several of the transistors, and the polarized electrolytic caps might also be damaged. In this case, as the pedal doesn't pass signal even in bypass mode, you need to start with the components that are in the audio chain at all times (the input and output buffer stages - the transistors are Q5 and Q6, respectively).

Like jfromel said, if your pedal has the D3 and R31 components, take them out and replace them with jumpers. This will make it PSA (9vDC) compatible. If yours already has jumpers there, it's already PSA-compatible.

/Andreas
 




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