EMI filters , look like capacitors

[danny davis]

We have these EMI filters , they look like metal radical capacitors at work

It's weird how to test them, if you test the EMI filter using the legs/leads it will test as a SHORT

But if you put a probe on the METAL casing of the EMI filter and use the other probe you will get to test the EMI filter this way

Also at work they use the METAL can IC packages, Why would they want to use the Metal can IC packages VS a Dual in-line package?

To Test for SHORTs , My manager put his Probe on the METAL CAN and the other probe on the leg/lead and tested each leg/lead referenced to the METAL can body

What kind of test is this called please?

Why would there be shorts to the Metal can's body of the transistor or IC op amp?

 

[Audioguru]

52 years ago ICs were in metal packages. I still have a few.

 

[danny davis]

Why do you test the METAL CAN transistor , using one probe on the Metal can casing and the other probe on the leg/lead to test for opens and shorts?

What is the advantage of using a METAL CAN transistor and IC metal can VS dual in line package? are they better at temp cold and high hot temps?

 

[chuckey]

If there was an advantage in using metal can encapsulation, we would still be doing it.
Checking the chip/transistor legs to the can is extremely crude and is hardly worth doing. Most circuits , if the metal can was not earthed, would work OK if the can was connected to any one leg.
Your suppressor is a series choke between the two wires with a capacitor going down from each wire to the case, its a PI filter. Put some swept RF into it, the response should be interesting.
Frank

 

[FvM]

Checking the chip/transistor legs to the can is extremely crude and is hardly worth doing. Most circuits , if the metal can was not earthed, would work OK if the can was connected to any one leg.

Many linear ICs in metal can, e.g. uA741 used to have the case connected to chip substrate and V-. In this case, the continuity test can show blown bond wires. Performing this test never came to my mind, though. There are more selective tests to check circuit health.

 

[danny davis]

There are more selective tests to check circuit health.

What other selective test to check?

 

[FvM]

What other selective test to check?

As far tests in unpowered state are concerned, checking for the existence of chip substrate diodes.

 

[danny davis]

checking for the existence of chip substrate diodes.

Explain more please? do you mean use the meter in diode checker mode? and which pins u testing?