Think i've just fried my Zoom B2

[Skywalker83]

Ok, so i went to pick up my pedal i bought off ebay. Got it home and plugged it in. i used a travel adapter to convert the American plug to European. Switched the unit on, it flashed on and then off... At that moment my heart sank when i realised what a t*at i've just been. The adapter for the zoom i have is an american adapter rated at what voltage...oh thats right 120v , and what voltage do we have in Europe, yup thats right 240v!!

Can't believe what an idiot i've been.

So i tried sticking fresh batteries into the device and switching it on. all that happend is the EDIT l.e.d flashes on and off constantly.

I'm presuming this L.e.d is a sub-circuit that is activated when the main input power route gets damaged, and lets you know there is a problem.

What are the chances that there is only minimum damage done and that the pedal is fixable? is it likely that the entire board is toast or just the power input stage?

[Bloodbath]

I'm not too familiar with the Zoom line but first thing I would check is to see if there is a diode connected to the dc jack. May have just popped it.You might have done worse though because I believe it should work with a battery even though the diode is popped.

[Skywalker83]

yes there appears to be a diode that is around the power input area of the circuit. (see pic)



Tomorrow i will go over the circuit with a multimeter and try to see what the damage is. Looking at the board there is no physical damage to any components.

Am i right in assuming if i get a reading through a component, that the component should be fine?

[Bloodbath]

Yeah, that diode is the first place I would check.

[Skywalker83]

Do popped diodes give off a funny smell?

Also do you know what type of diode this is?

[Bloodbath]

Not too sure. I haven't ever smelled one that was freshly fried. I would imagine it would.

It looks like a 1N400x (where x is a 1,2, etc.) type. It will say it on it. Make sure the grey stripe goes in on the same side if you replace it. They are polarized.

[Skywalker83]

it's a 1N4003, rated at 200v.

[Bloodbath]

If your multimeter has a continuity setting, test it for continuity. Make sure the pedal doesn't have any power supply hooked up to it when you do.

[Skywalker83]

Ok i've just tested the diode, i get a reading of 700, when the multimeter is set to the diode measurement.

What does this mean?

[Bloodbath]

Not sure what multimeter you have but here are some instructions.

DIODE TEST

1. Set the function switch to the diode test position.
2. Press the button until the symbol appears in
the display.
3. Insert the black test lead banana plug into the negative
(-) jack (COM) and the red test lead banana plug into
the positive (+) jack (!).
4. Touch the test probe tips to the diode or
semiconductor junction you wish to test. Note the
meter reading.
5. Reverse the probe polarity by switching probe position. Note this
reading.
6. The diode or junction can be evaluated as follows:
A. If one reading shows a value and the other reading shows OL, the
diode is good.
B. If both readings show OL, the device is open.
C. If both readings are very small or 0, the device is shorted.

The value indicated in the display during the diode check is the
forward voltage.

[Skywalker83]

ok, after reading a couple of articles about diode reading, acording to the readings i get the diode is fine. I've also measured reading across other various components on the board and all of them having given off readings.

So any other ideas that the problem could be?

Could it be that i've scrambled one or all of the microchips on the board, but yet cause no damaged to other components?

[Skywalker83]

Yeah i get A.

i get a reading of about 700 in a forward direction and "OL" or a "1" in the case of my multimeter.

[Skywalker83]

Something else i just tried which shows me that some aspect of the pedal is working is, i tried doint a hard reset (where you would reset all the factory settings) and it seemed to work, so i know some aspects, such as the display and the buttons of the pedal is working.

[Bloodbath]

Well, if you did something to the microprocessor in there. I believe you are probably going to need to buy a new pedal. Even if you buy a new chip, you will have to know how to program the chip.

[Skywalker83]

was just doing some more tests, and somethings came up that i wanted to ask about.

I was taking a measurement across the input and output (shown in the lower mid left side of the board). I had the black probe from my multimeter on GND and tried the red probe on IN, then OUT. i got a reading of about 3v between OUT and GND, but got 0v between IN and GND.

Should i be getting a reading between IN and GND?

And, the diode above the IN, OUT and GND, in one direction i get 1153 and the other i get about 700. all theother diodes give me "OL" one way and about 700 the other. what does this mean for that diode?

Also , from the picture (i know it's quite blurry) are there any things that you can see that i should be testing that might narrow things down?