Diode marking code. Need help

[frantal]

I am repairing a 220VAC/5VDC power supply for a router. I am looking for to identify a through-hole diode with marking code 2 18 (printed in two rows: first row 2, second row 18) that I marked with a ? on the photo attached. On this photo you can see the diode at the upper left corner and the PCB of the power supply where I drawed part of the circuit (High Voltage section) to help understanding which diode could be it. thanks in advance for any help!

 

[VEBill]

1N218? ?? Do you suspect the diode? Why? Have you tried to find the manual/schematic for this power supply?

Also, why not just find a replacement power supply? If it's not more than 2A current output, then you should be able to easily repurpose another surplus 5VDC PS, perhaps just splicing or replacing the output cable. 5VDC adapters (power supplies) up to 2A are extremely common.

 

[frantal]

I don't suspect the diode..., it is shorted besides other components. I tried to find the schematic of this DSA-0151A-05, but no success... About repurposing another power supply I had thought about, but at this point that I susbstituted all the broken components (except the diode!) it is just a satisfaction to finish what I started. In any case thanks for your answer

 

[itsmoked]

A diode shunted with a resistor..
A different diode when the design already has two of the most common types ever used in it, 1N4148 and 1N4004.

Makes me think it might be a zener or not a diode at all.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[benta]

Could it be "Z 18" instead of "2 18"?

Benta.

 

[frantal]

I watched very "deeply" using a microscope, because it was my idea too, but it is a 2. Maybe it will be necessary to draw all the schematic of High Voltage section, but it will take me some time. I will try...

 

[VEBill]

http://lcdpayless.com/productpage.php?productId=6799

 

[frantal]

Thanks for the suggestion, but I already tried to order one power supply from U.S. with the same model code, but I realized it was 100-120 V as primary that it is suitable here (220V). Yes.. I can write to ask, but I would try to repair this one, at this point.

 

[ScottyUK]

What does "worldwide input voltage" mean, if it is not a universal supply which will work on typically 85V AC to 250V AC. Seems like a good link.


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If we learn from our mistakes I'm getting a great education!

 

[zzzjim]

Self distruct mode PSU , any repair may well be short lived , and lead to a more explosive failure . Newer design is best way to go .

The natural resilience of the componets has been use up once already !

 

[Comcokid]

Your diode appears to go gate-to-source on a MOSFET. Assuming N-channel, most likely that would make it a zener to limit the gate voltage to be less than 20Volts - a typical protection for a MOSFET gate. A 18 volt zener would be ideal.

 

[frantal]

Thanks I will try and then I will tell you... just to learn...!

 

[itsmoked]

Excellent sleuthing Comcokid! You nailed it.

Keith Cress
kcress -

http://www.flaminsystems.com