Think i've just fried my Zoom B2

[Skywalker83]

OK another update.

Whist testing the diodes with the battery voltage running throught the circuit, and the multimeter set to the diode function,all the diodes give a reading of around 700 in one direction and "OL" in the other.... apart from ONE diode, a which looks like a DIAC (very small , clear shell with an orange centre, with a yellow band round the outside). The diode about the IN, OUT and GND, gives a reading of 0.64 in one direction and about 0.75 in the other direction.

Does this mean that this diode is shorted?

[Bloodbath]

You probably won't get a reading from the input jack unless there is a cable plugged into it.

If you have any doubt about a diode being good or not, I would just replace it. They are cheap enough.

Check that resistor by the power supply. Maybe check the capacitors to see if there are any that have a low voltage rating. Maybe you supplied too much voltage to one of them.

I'm running out of ideas. Personally, I would replace the diodes, check and/or replace the resistors and capacitors and then if that doesn't work start thinking that one or more of the chips are bad.

I was hoping the Mark would come along with some ideas by now.

[Robert M. Martinelli]

Check the 3-pin chip close to the 1N4003 diode, that's most likely a Voltage Regulator, with fresh batteries or a proper AC adapter you'd have some voltage between the center pin ( GND asuming it's a positive VR ) and either end ( input and output ). I'd expect a 2-3 VDC drop across that IC, if too much voltage drops there the effect's chips might not be able to operate correctly.

Also, be aware that, to correctly test components on your PCB you might need in some cases to disconnect them at least on one side, otherwise your readings can be spoiled by other components adding a "parallel" resistance ( e.g. diodes reading a forward voltage even when reversing your DMM's probes ).

Hop this helps

Best regards

Bob

[cjlectronics]

If the display is working and you can interact with the buttons then most likely the 1N4003 is good. That is a reverse protection diode that protects the electronics in the event the batteries or AC/DC adapter is applied in a backward polarity.

Not to add salt to the wound, but it sounds like the over voltage (if it was a 120v unregulated AC Adapter that was plugged into a 240v then you doubled the output voltage going into the Zoom B2) took out some components. Which ones will take an oscilloscope and SMT desoldering tools to fix. Maybe it is just a regulator... but if the display and buttons work then parts of the CPU chip is working. However, what ever is feeding the DSP or the DSP itself it not getting the input signal.

My guess is you will need a service manual and lots of patience.

Good Luck...

CJ

[average]

Was there ever a resolution to this thread?