Testing 4116 RAM chips out of circuit

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Ed in SoDak
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Joined: Thu Jul 24, 2014 1:03 am

Testing 4116 RAM chips out of circuit

Post by Ed in SoDak »

Would it be possible to test 4116 RAM out of circuit for possible shorts in the power pins? Maybe by using the diode check function of my DMM to the 12v, -5 and +5 pins to ground? I have a bunch of pulls, one or more of which may have a short. I'd like to be able to cull it out by means other than testing for smoke in an otherwise working TS1500. I've already blown the MPS6727 power supply transistor twice while trying to fix the bad RAM in it.

Thanks!

-Ed
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Ed in SoDak
Posts: 24
Joined: Thu Jul 24, 2014 1:03 am

Re: Testing 4116 RAM chips out of circuit

Post by Ed in SoDak »

My tests with a DMM were inconclusive, but I have two ued chips that heat up the transistor quickly, so gotta be a short. Ordered a bunch from Jameco along with spare transistors and regulators so I should be all set to start pulling the RAM and socketing it when the parts arrive.

Funny thing is, I can boot the 1500 with a RAMpack. Although the internal RAM is defective it still has 16k using the external pack. At least I can use it this way till I get a fix in.

-Ed
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