Aiwa CDC-MP32 Headunit Unresponsive

[D132]

Should I take R715 out of the circuit to check it?

 

[Perry Babin]

OK. Did you get the replacement diode from a reputable distributor?

Does it have the correct markings for a 5.1v Zener?

 

[D132]

Yes
It says 1N4733A on the diode, says 1N4733A 5.1v on packaging

 

[Perry Babin]

Can you borrow a different meter?

 

[D132]

Only another manual meter that is about the same as my yellow meter

 

[Perry Babin]

No friends with a meter you could borrow?

 

[D132]

This is the only other one I could potentially have access to, would it be worth trying to borrow it?

 

[Perry Babin]

I don't know. I'm just looking for readings that resemble what I'd expect.

 

[D132]

What should I check next?

 

[Perry Babin]

If you bridge across D716, what DCV do you read across D712?

 

[D132]

Bridge across D716? As in remove the diode and put a jumper or read across?

If it’s reading across, 13.37 reading from input D716 and output D712 (13.37v is source as well)

 

[Perry Babin]

You don't have to remove it.

I don't understand the second statement.

 

[D132]

I had the positive probe at red and negative probe at blue, I wasn't sure what you meant as to bridge across it

 

[Perry Babin]

Bridge across, solder a wire that connects the two terminals together.

 

[D132]

Bridged D716, D712 reads 3.74v, source is 13.3v

 

[Perry Babin]

Do you have any spare resistors of about 47k ohms?

 

[D132]

Surface mount or with pins?

 

[Perry Babin]

You could make either work but the axial type leaded resistors would be easier?

 

[D132]

Not sure what type this is but I have 2 of these. They are 47k ohms give or take (within tolerance)

 

[Perry Babin]

For D712 (or an equivalent diode that you purchased), ground the anode, Connect the cathode (striped end) to the resistor. Connect the free end of the 47k resistor to the 12v terminal of the power supply. What's the DCV directly across the diode?

^^^ This must be done with the diode out of the circuit.

Absolutely do NOT power the head unit up with the diode out of the circuit.