Repare job on a DOD Grind

[Night0wl]

Hi all,

I am trying to fix a DOD Grind Rectifying Overdrive pedal for a freind and I have a slight problem.

The guy says he plugged a 12v power adapter into it instead of 9v and it stopped working. I am not sure whether or not the supply was AC or DC, or what Amperage as that was all the info he could give me.

When I opened up the box it had a blown cap (47uF) and next to it a blown diode (n4001). I replaced the cap with 47uF 63v instead of the original 16v cap and I substituted a n4003 in place of the n4001 diode. I made sure the polarity was correct on both components.

Now, when power is plugged into the pedal the LED stays on all the time and there is no signal. What else could have went with the cap and diode?

Any ideas?

Thanks
Shane

[jrc4558]

replace CD4007 perhaps?

[choklitlove]

i have a similar problem with something else.  http://www.diystompboxes.com/smfforum/index.php?topic=45775.0

just posting to ask for a "Commercial Pedal Repair" forum.  i know several people want it.

it would really help us get the help we need without being OT.  it just doesn't fit in any forum yet...

[MartyMart]

If both the cap/protection diode were "blown" that means the 12v ( AC?) got further into the circuit.
As mentioned, check IC's and any other polerized caps "down the line"
Resistors and NP poly caps etc should all be fine.

MM.

[Night0wl]

I have done a visual check on the rest of the circuit and all other caps look fine. The blown cap and diode in question were actually blown! The cap's top was blown off and the diode was in two pieces. I guess it could be the IC (MC14007) but I am not sure how to check it. If it is the IC I may have to pass on fixing the pedal because I can't get one. Is there a way to test it while it is still in the circuit?

[Mark Hammer]

The 4007 likely IS blown if the state of the switch and status LED do not change.  Happily, it's a cheap and widely available component. with no subtle suffix-related variations you need to keep an eye out for.  Any one will do.

This is why manufacturers make a big deal out of using ONLY the recommended power supply.  There are tons of other perfectly acceptable power supplies one could use, but apparently the odds of users understanding fully what the ground rules are for their selection and use are pretty slim.  Rather than provide lengthy tutorials on how to select an appropriate power supply, they just say "Use ours" and leave it at that.

[Night0wl]

I changed the 4007 IC and now the pedal is switching on and off. However, there is no sound at all.

Could a polarised cap be blown even though it looks fine? Could there be a blown tranny or is it most likely a cap?

Thanks
Shane