Fly back diode failure

[jishnuprakash]

hi,
I am using a 1N4007 and 53ohm resistor as flyback circuit for operating solenoid coil
now I am facing problems with failure of the diode, diode has found open in multiple boards
what could cause this problem ?, is there any equation selecting the resistance value ?
or is it problem with diode itself, I am using MIC make 1N4007

 

[betwixt]

It should be fine in that application, either the diodes are sub-standard or they are being damaged during assembly.

Brian.

 

[Razerwire]

That diode should work perfectly unless your voltage/power readings for the circuit are WAY off.

 

[jishnuprakash]

That diode should work perfectly unless your voltage/power readings for the circuit are WAY off.

hi,
thanks for the reply
we are using the above circuit to drive a 24V 2.5W AMISCO , when I checked coil resistance
after failure it shown the normal value, is there any chance for over voltage or current if there is no coil damage ?

 

[FvM]

Besides the point, that the 56 ohm resistor is effectively useless but doesn't disturb, I'd consider the circuit as just standard. I don't see a way to damage the diode by electrical means.

--- Updated Mar 3, 2022 ---

Possible failure scenarios are e.g.:
shorted solenoid coil -> transistor damage
massive supply overvoltage -> transistor + solenoid damage
supply reversal -> R103 burn, without R103, diode and possibly transistor can be damaged

 

[Warpspeed]

Diodes usually fail shorted if the ratings are exceeded, which cannot really happen in your circuit.

Its much more likely you are the victim of a batch of sub standard diodes from a third world country.
Suggest you dump the lot, and buy some more from a well known reputable component house.
A reputable seller will have full ISO traceability and paperwork right back to the manufacturer.
If you buy direct from China, it may be o/k or maybe not.
Sadly, this type of thing is becoming a lot more common.

 

[cupoftea]

the only thing i can think of is , is the diode the right way round in the actual cct?

 

[Easy peasy]

how fast are you switching Q104 ? ( frequency )