Cannot create Rejects for TMV on a medical instrument with an LCD

[SteHa]

Hello All,
Hope I can get some suggestions.

In the process of developing a protocol for an attribute TMV on a medical instrument with an LCD. Part of the Final functional test includes a LCD test.

I've been informed that we are not able to create rejects and rarely come across them in testing.

What do others do in TMV situations where rejects cannot be created?

Thanks,
Steve

 

[shimonv]

Hi Steve,
Why do you need to create a reject? why not simply conform that you get the correct / expected output?

Shimon

 

[SteHa]

Hi Shimon,
We are required to perform a Test Method Validation so that we have objective evidence that the test method is suitable for its intended purpose and capable of producing valid results.

Rejectable parts are a requirement to demonstrate that the test method can actually detect rejects. If the test method cannot consistently detect rejects we will have type 2 errors in the field which is not good for the patients or healthcare provider.

Thanks

 

[shimonv]

I see. I'm afraid it's is not feasible to find a solution without detailed information on the requirement, the risks and what exactly are you trying to test and when exactly do you do the test.

Shimon

 

[yodon]

You mention that you did have some rejects in the past - don't presume those are available for use in testing?

What is the nature of the test? Visual? Electronic? Are there ways you might be able to "fake" a reject without actually create an actual reject?

 

[SteHa]

Hi Again,
Although finding a solution for my specific situation would be great, it would also be valuable to hear if anyone else has run into this type of problem with TMV.

I would be surprised if this has never been encountered before.

Thanks,
Steve

 

[SteHa]

You mention that you did have some rejects in the past - don't presume those are available for use in testing?

What is the nature of the test? Visual? Electronic? Are there ways you might be able to "fake" a reject without actually create an actual reject?

Hi Yodon,
The test is visual. Looking for brightness changes and missing segments.

I believe they encountered a couple of failures many years ago but those units are no longer available.

The FW drives the segments lighting up and we do not have access to the FW to change it.

Tomorrow I will be getting a walk through on how the test is conducted and hopefully I can work with the tech to see if there are any other ideas on creating some type of failure.

Thanks,
Steve

 

[Ronen E]

If such failures are so rare in the field, based on a risk-management approach such testing is most likely redundant and represents inefficiency. I would document such risk analysis; remove the test; and suffice with monitoring and trending (the latter only if necessary) until otherwise indicated.

QC means finding and eliminating bad parts after they’ve been made —> waste.
QA means making sure bad parts won’t be made in the first place.
It seems that you have effective QA in that respect, and thus QC is much less necessary (and somewhat of a waste in itself). Congratulations!

Cheers,
Ronen.

 

[normzone]

I have a bad idea - if the failure mode is one that can be manually induced, you could damage a piece of product accordingly for a test piece.

I could be way off base, but the flaw mode reminds me of damages done to LCDs by pressure, causing bright spots, and by pixel failures, causing .... well, little dots of unintended color or no color.

 

[SteHa]

Hi Ronen,
I appreciate your insight. Having very good quality is a great problem to have!

I've learned more today and there is the possibility to create some of the failure modes to run the TMV. We are also going to work with the contract manufacturer of the instrument to see if they have any fall out for LCDs in areas that are harder to create. They might be seeing more than we do.

Thanks
Steve