(Topic ID: 79880)

How static sensitve are 5101 cmos ram chips ?


By sixpakmopar

5 years ago



Topic Stats

  • 21 posts
  • 14 Pinsiders participating
  • Latest reply 5 years ago by Richard_BoK
  • Topic is favorited by 1 Pinsider

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    #1 5 years ago

    A little while back I had a completely rebuilt CPU lock up in my time warp, bench testing, diagnostic lights (leds) and forum people all say the 5101 chip is bad but no definite reason for it to fail. Since then I just put in another completely rebuilt CPU as it was an easy to get it up and playing. All the crimp connectors have been replaced, power supply and sound board have all new capacitors installed. Well last Friday night my friend was playing and it locked up again with the replacement CPU (both leds on). I have not done any more testing other than checking the power cord and sure enough the ground prong is bad (with a multi-meter hooked up I can wiggle the prong and it will lose continuity at times).
    I am wondering if static electricity in addition to the bad cord ground could have caused these 2 5101 chips to go bad? It is the heating season (not news to anyone I am sure) and I heat with forced air which does create a very dry indoors environment and I do notice static shocks somewhat regularly in my carpeted basement.

    Thanks Ed

    #2 5 years ago

    I would test them in another known good board, maybe a Bally 35 mpu. They do go bad over time, 30 years. Any IC's made by AMI are usually crap over time.

    #3 5 years ago

    They are Not socketed

    #4 5 years ago

    Any CMOS chip is considered Static Sensitive. That said I have handled many 5101 chips and never used the proper grounding recommendations (shame on me) without harmful results.

    If you read the datasheet for the 5101 you will find it was actually built with special circuitry to protect again static discharge harm.

    For two in a row to go sounds more localized than an ESD event.

    #5 5 years ago

    Any MOS device is very sensitive to static electricity damage. At minimum you should be grounding yourself/tools prior to handling. The 5101 series has been around for a long time, so even if it has not been damaged by static, age may be the cause.

    http://www.informit.com/articles/article.aspx?p=21704&seqNum=3

    #6 5 years ago

    The 5101 is probably the single most sensitive IC in all of pinball.

    --
    Rob Anthony
    Pinball Classics
    http://LockWhenLit.com
    Quality Board Work - In Home Service
    borygard at gmail dot com

    #7 5 years ago
    Quoted from Borygard:

    The 5101 is probably the single most sensitive IC in all of pinball.
    --
    Rob Anthony

    I second that. I don't think I have had any other chip go bad just sitting in my parts box. You look at one of these wrong and it will fail!

    #8 5 years ago

    I seriously disagree. It's age of the ic's. Seen many other ic's other than 5101 that have brittle legs. Have handled a large number of 5101's over the years.

    #9 5 years ago
    Quoted from Taxman:

    Any CMOS chip is considered Static Sensitive. That said I have handled many 5101 chips and never used the proper grounding recommendations (shame on me) without harmful results.

    All chips should be considered static sensitive, but yes CMOS more so. And the thing with an ESD discharge, it may not always fail right away but you definitely do remove years off its life.

    I've got a few dead ones on my bench right now. I also keep an old 2101 laying around as a test chip so I don't blow my last couple 5101's/

    #10 5 years ago
    Quoted from Borygard:

    The 5101 is probably the single most sensitive IC in all of pinball.

    That was my understanding. Maybe the age (assume original as they are both soldered to the board) has something to do with it and they were just ready to crap out. Just seems odd both in the same machine with all that has been done to bulletproof the boards there could be an issue to cause this. Maybe the cord ground prong with intermittent connectivity has nothing to do with it but will be corrected.
    Ed

    #11 5 years ago

    5101 RAMs fail all the time. By far the single most replaced IC I deal with. I have NOS ones and some are bad right out of the tube. After rebuilding a board it is not uncommon for one to fail 1 - 2 hours into a burn in test.

    The 5101s are AMI brands on WMS boards often. That is a double whammy. AMI brand ICs are notoriusly flakey compared to motorola, st, or fairchild.

    #12 5 years ago

    In all my years (25+) working on electronics I never once used a grounding strap or anything and only once, have I damaged a CMOS chip due to static. It was obvious at the time as there was an actual spark that jumped between the IC and the board that it was being inserted into.

    That being said, RAM chips (any kind - includes SD, USB, etc) are prone to eventually fail as they have only so many read/write cycles that they can perform (most modern RAM list the cycle number in the spec sheets). I know several people are working on the issue and are trying to increase the number of cycles (never mind new types of memory).

    #13 5 years ago

    Wow...

    First - for ESD sensitivity, 5101's are within Class 1 of the HBM voltage range so they are are EXTREMELY susceptible to ESD. This means the part can be damaged by voltages as low as 250V. Human touch can easily generate a charge up to 35000V (yes, 35KV). The charge must be at least 3Kv before you can even feel it. So if 250V can kill the part then chances are you would probably never feel the zap. To actually see a spark, the charge must be greater than 4KV. If never practicing ESD safe work habits then you can easily have what is called 'latent' damage or "walking wounded". For example, only one bit can be affected within the entire device....and it may fail (or work) depending on room temp or operating voltage. Part can be affected but you may not even know it. You may not be killing parts immediately but I'm sure you have created latent defects based on this handling. Typical logic devices (74xx parts) are in the class 2 HBM range (2KV - 4Kv) so you could potentially be affecting them and nearly every other logic family as well.

    Second - Static RAM chips such as 5101's do NOT 'eventually fail' just due to use and they do NOT have a limited number of read/write cycles. You are mixing static RAM with NV memory.

    #14 5 years ago

    Great info as always Ed! I like the walking wounded analogy. It's always amazing to me how many ways ICs can fail but still seem okay until certain conditions are present. That explains a lot right there.

    #15 5 years ago

    Remember the old saying in electronics:

    "Any component can fail at any time for any reason."

    #16 5 years ago

    ... and always while giving a demo.

    #17 5 years ago

    Or when you don't have any in your tool box. Thanks Ed for shipping out fast.

    #18 5 years ago
    Quoted from LongJohns:

    In all my years (25+) working on electronics I never once used a grounding strap or anything and only once, have I damaged a CMOS chip due to static.

    Why tempt fate? and that being said, we also have grounding straps, bracelets, all in easy reach for use in our shop. They are almost never used - I admit I am so busy I often don't use them either. But I do discharge ESD by grounding myself prior to handling. At minimum, touch yourself/tools to the ground braid before handling a sensitive IC. Its a good habit to get into, at least for memory and CPU ICs. Our shop gets very dry in the winter, and I often get a static shock when I reach for the bench power switch.... a helpful reminder to me to be cautious throughout the day.

    #19 5 years ago
    Quoted from wayout440:

    But I do discharge ESD by grounding myself prior to handling. At minimum, touch yourself/tools to the ground braid before handling a sensitive IC.

    That's the big thing. After a while it becomes 2nd nature to always be auto grounding yourself and we do not blow stuff up on a microscopic level.

    The main problem is Joe Average doing ship swaps in a nylon jacket and spandex pants in the winter while wearing woolen socks on a shag rug with one hand in his back pocket. I exaggerate, but any one of those things = esd discharge.

    #20 5 years ago
    Quoted from Patofnaud:

    That's the big thing. After a while it becomes 2nd nature to always be auto grounding yourself and we do not blow stuff up on a microscopic level.
    The main problem is Joe Average doing ship swaps in a nylon jacket and spandex pants in the winter while wearing woolen socks on a shag rug with one hand in his back pocket. I exaggerate, but any one of those things = esd discharge.

    Or people shipping ICs in styrofoam or shrinkwrap instead of anti-static foam / anti-static bags. I always love when that happens. I'm thinking.. yeah, I'm lucky if any of these work at all.

    #21 5 years ago
    Quoted from sixpakmopar:

    A little while back I had a completely rebuilt CPU lock up in my time warp, bench testing, diagnostic lights (leds) and forum people all say the 5101 chip is bad but no definite reason for it to fail. Since then I just put in another completely rebuilt CPU as it was an easy to get it up and playing. All the crimp connectors have been replaced, power supply and sound board have all new capacitors installed. Well last Friday night my friend was playing and it locked up again with the replacement CPU (both leds on).

    Static electricity can cause components to fail.

    But are you sure this 5101 is the reason for your lockups?
    There are more possible causes that can result in a game to lock up. E.g. the interboard connector is famous to cause trouble as well.

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