Author Topic: help needed identify zener diode value  (Read 373 times)

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Offline dicky96

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help needed identify zener diode value
« on: November 13, 2018, 01:42:18 pm »
Hi guys
I'm fixing this RGB LED par can now

It has 3 channels, each channel has it's own DM0565R swicth mode psu, and I assume the DMX controller sets the pwm for each channel,

Basically one of the DM0565R has gone bang.  So much so that pin2 of the device has completely vaporised.  This also took out the fuse, the bridge rectifier and I think was a NTC thermister to prevent inrush current

Currently I put a wire link instead of the NTC thermister, made a bridge rectifier out of 4x 1N4007 (there is plenty room in the par can housing) and conected via a 60W light bulb in series with the mains.  Now two of the DM0565R are running.   So I replaced the blown DM0565R and also looked around the components close to that device.  I have an open circuit 000 ohm resistor and a short circuit zener.

The 000 I assume I can just replace with a wire link.

The zener is short so I don't know the rating.  It is connected from pin 3 of the DM0565R to Ground and according to the example schematic on the datasheet a 22V zener is suitable.  It looks to be an over voltage protection device only. http://pdf1.alldatasheet.com/datasheet-pdf/view/85398/FAIRCHILD/FSDM0565R.html see ZD 101 schematic 1 on page 14.  Mine is in the same position in circuit.

I could unsolder one from another channel to measuer the voltage rating.   I tried to measure in circuit on one of the other channels but the DM0565R kicks on at about 10.5V  so I can't get a reading.  I doubt it is critical though.   

The question is what is the Wattage rating supposed to be?  It's a little 0805 (I think) cylindrical SMD device.  There are no marking on it.

Also how do I select a suitable NTC?  The original is blown to crap.

Photo attached but the camera on this phone is crap and I left my better phone at home lol

Any advice??

« Last Edit: November 13, 2018, 01:46:36 pm by dicky96 »
 

Offline dicky96

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Re: help needed identify zener diode value
« Reply #1 on: November 14, 2018, 12:59:03 pm »
No one?

Here are some better pics if that helps.  The zener is on pin 3 (Vcc) of DM0565R to hot Ground.

 

Offline stj

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Re: help needed identify zener diode value
« Reply #2 on: November 14, 2018, 05:03:33 pm »
i would meter a good one.
i would also clean the filth off the board and work out why the screws are rusty as F.
if you get filth on the board, and then it traps moisture - well that's when shit can happen!
 


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