Testing a HD74LS244 chip

Casethecorvetteman
Master Tech

Posts: 1,219

Testing a HD74LS244 chip Mar 11, 2016 13:05:39 GMT -5

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Post by Casethecorvetteman on Mar 11, 2016 13:05:39 GMT -5

Hi all

How do i test a HD74LS244P chip?

I have an issue that occationally comes and goes, and it seems to go away completely after the device runs for 30-45 minutes. The LS244 is part of this circuit.

Is it possible for these to become problematic like this? It is in excess of 20 years old.

Thanks

mastertech
Global Moderator

Posts: 3,538

Testing a HD74LS244 chip Mar 11, 2016 13:28:34 GMT -5

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Post by mastertech on Mar 11, 2016 13:28:34 GMT -5

These types of ic's generally do not go intermittent. To do a basic test of these ic's just use your dmm on diode scale and connect neg probe to gnd pin and then test with pos probe on other pins and look for any low readings. Then do same test with neg probe on power pin and test remaining pins with pos probe, again looking for any low readings. Inputs and outputs can be tested but you need an idea of what should be happening.

Casethecorvetteman
Master Tech

Posts: 1,219

Testing a HD74LS244 chip Mar 11, 2016 23:18:34 GMT -5

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Post by Casethecorvetteman on Mar 11, 2016 23:18:34 GMT -5

Yeah ill have to test that, the intermitent problem is graphical glitches, ive swapped out the 5814 RAM chips with no change, there is 2x CXK58257 RAM chips that im having trouble finding replacements for.

Seems like a connection issue to me though, because id expect a faulty part would stay faulty and not come good with warm up!

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Post by Casethecorvetteman on Mar 11, 2016 13:05:39 GMT -5

Post by mastertech on Mar 11, 2016 13:28:34 GMT -5

Post by Casethecorvetteman on Mar 11, 2016 23:18:34 GMT -5

Shoutbox