Testing IC's/Eproms

Twin Paradox

New member
Joined
Jul 14, 2010
Messages
16
Reaction score
0
Location
Virginia
I know this is probably an extremely basic and noobish question, but how can I test an IC or an Eprom to see if it is operating correctly? Also, other than having a bad physical connection, are there any other visible cues that would indicate a bad IC or Eprom? I have tried researching this and can't really find any helpful information.
 
I'm only a noob too, but for ICs I'd suggest reading up on oscilloscopes, logic probes, and logic comparators. Someone wrote a handy piece about using a logic probe on a PacMan that I found a nice introduction to the subject (try googling it). And the Atari Book is a good introduction to ICs. Most IC problems are not going to be visible.
 
I know this is probably an extremely basic and noobish question, but how can I test an IC or an Eprom to see if it is operating correctly? Also, other than having a bad physical connection, are there any other visible cues that would indicate a bad IC or Eprom? I have tried researching this and can't really find any helpful information.

Fresh out of college I accepted my first job as an electronic technician. That was 12 years ago and I have accumulated a lot of knowledge...

As someone being new to the troubleshooting aspect of the hobby, I would have to recommend the finger method. While it may seem stupid, an IC or eprom will only get so hot when operating properly. Fresh out of school I was taught by the senior techs to first look for obvious things, touch each IC (a side note here, please use a static strap or equivalent) looking for a hot chip. I cannot tell you how many times I have fixed a board using that method.

Over the years I have acquired the skills to use an oscilloscope as well as a logic analyzer. It took me quite a while to fully understand and use those tools, beware that you are looking into quite a steep learning curve. With that said, all the meter, scopes and analyzers will not be of any help if you have no idea of electronics. The more that you know about electronic theory the better troubleshooter you will become.
 
Put the ROM/EPROM in a programmer... Read it several times... and verify the correct checksum. Also verify they read the same each time.

If the checksum changes each time you read it, the chip is bad or has bit rot and needs reprogramming.

If the checksum isn't correct then the chip is bad or has bit rot and needs reprogramming.

This works for 99+% of the time.

Once upon a time I bought a Data I/O Series 22 EPROM programmer with a PROM programming module installed. It failed self tests with a bad ROM but all the ROMs had a good checksum! Turns out one of the EPROMs would read good on the programmer but wouldn't work right when running "at speed" in the circuit. Programming a replacement EPROM fixed it.

RJ
 
Back
Top Bottom