Y
Yzordderrex
- Jan 1, 1970
- 0
The thread was hijacked and by the time we got to post number 153 it
had morphed into something else which had nothing to do with my post -
Heheh - So I figured to start fresh. I placed OP at the bottom for
reference.
We stuck a couple of controls in the environmental chamber and brought
them down to 20 below. Took them out and walked them downstairs to the
high power lab and plugged in in - Boom. Blew up 2 out of 4. Looks
like the moisture getting into the drive was enough to kill the power
supply. Drive looks clean as a whistle when the moisture gone.
I had mentioned to the group that I had thought contamination was
killing units. One of the other (young & green) engineers would offer
up the fact that units would come back clean in an effort to shoot down
contamination as a cause. So now we will have a meeting on Monday and
I have all the ammo I'm going to need. Clean up the packaging and if
failures continue we will take another look.
Boss is having a leadbend fixture made as well. Thanks for all the
comments that apply I'll sort them out and send them up the chain.
regards,
Bob
I have a small 480v 5w flyback power supply that has had a large number
of field failures. In general the failure rate is about 0.4%, one out
of 250 units. This I can live with. One particular customer in
Northern California has had a 25% failure rate. Most of the units come
back filthy so that there may be an environmental aspect to the problem
as well. I think units are in an air stream which may be blown in from
a rooftop intake. We have beat the crap out of the power supplies here
at the factory and have not been able to kill them. Heated transistors
to 150c, put 1500v dc on the supply, etc and they keep on running. I
am begining to think there may be a stress related problem with the
lead bend. Production is bending a complete 90degree at the drain lead
of the mosfet directly at the package. It looks like the package
ruptures and sends plasma out and destroys the clamp diodes and control
chip and so forth. Destruction is very complete here.
So question is then - has anybody ever heard of failures related to
this type of handling? I will contact mosfet vendor after discussing
here.
thanks,
Bob
had morphed into something else which had nothing to do with my post -
Heheh - So I figured to start fresh. I placed OP at the bottom for
reference.
We stuck a couple of controls in the environmental chamber and brought
them down to 20 below. Took them out and walked them downstairs to the
high power lab and plugged in in - Boom. Blew up 2 out of 4. Looks
like the moisture getting into the drive was enough to kill the power
supply. Drive looks clean as a whistle when the moisture gone.
I had mentioned to the group that I had thought contamination was
killing units. One of the other (young & green) engineers would offer
up the fact that units would come back clean in an effort to shoot down
contamination as a cause. So now we will have a meeting on Monday and
I have all the ammo I'm going to need. Clean up the packaging and if
failures continue we will take another look.
Boss is having a leadbend fixture made as well. Thanks for all the
comments that apply I'll sort them out and send them up the chain.
regards,
Bob
I have a small 480v 5w flyback power supply that has had a large number
of field failures. In general the failure rate is about 0.4%, one out
of 250 units. This I can live with. One particular customer in
Northern California has had a 25% failure rate. Most of the units come
back filthy so that there may be an environmental aspect to the problem
as well. I think units are in an air stream which may be blown in from
a rooftop intake. We have beat the crap out of the power supplies here
at the factory and have not been able to kill them. Heated transistors
to 150c, put 1500v dc on the supply, etc and they keep on running. I
am begining to think there may be a stress related problem with the
lead bend. Production is bending a complete 90degree at the drain lead
of the mosfet directly at the package. It looks like the package
ruptures and sends plasma out and destroys the clamp diodes and control
chip and so forth. Destruction is very complete here.
So question is then - has anybody ever heard of failures related to
this type of handling? I will contact mosfet vendor after discussing
here.
thanks,
Bob