100k resistor - potential problem

[heisthl]

I like to use 2 watt metal films for plate resistors. Recently I've seen some failures with this part number from Mouser:

594-5083NW100K0J

they just go open with no visible indication, and I've had one identical failure with a 24k value of the same series. The fall out is by no means massive, but even 2 in a hundred is frustrating because they work perfectly during testing and fail with out warning a few weeks later.

Never had a problem with these:
71-CCF02100KJKE36

Hope this helps on your next build list. HH

[ToneMerc]

Henry, thanks for the heads up. I've been religiously using the 594-5083 as bleeders and the 594-5093(3W) at the bias and PS nodes. In my just completed build I used the 5083 over my normal choice of the CPF1 at the bias safety tail position.
I know there have been problems in the past with the 5073(1W) as well. This makes me wonder if the 3W series is next and if I should start to avoid the 594-50xx series. In the past I've always wanted to go 100% CPFx in the power supply, however the values at Mouser are limited when compared against the 594-50xx series.

TM

[Structo]

That's not good for a part rated at 500v to go bad.

It would seem that Vishay would want to know about that and make improvements where they can.

[dogears]

I think Andy Fuchs had issues with these like 5 years ago. Well aware of the problem.

My advice: Don't get cute and reinvent the wheel.

I like to use 2 watt metal films for plate resistors. Recently I've seen some failures with this part number from Mouser:

594-5083NW100K0J

they just go open with no visible indication, and I've had one identical failure with a 24k value of the same series. The fall out is by no means massive, but even 2 in a hundred is frustrating because they work perfectly during testing and fail with out warning a few weeks later.

Never had a problem with these:
71-CCF02100KJKE36

Hope this helps on your next build list. HH

[heisthl]

I think Andy Fuchs had issues with these like 5 years ago. Well aware of the problem.

My advice: Don't get cute and reinvent the wheel.

Off the top of your head, are there any other similar questionable parts that should be avoided?

[FUCHSAUDIO]

That series of resistors sounded good, was low noise, and we were hit about 50 times (that's fifty amps worldwide) that simply stopped working !

My Engineer friend Ted said " they don't look like any 2-watt no-way no-how". They are not being over used ( a plate load is like .400 w dissipation), but they just opened for no reason...AVOID THEM in tube things.