IC testers for TTL, CMOS, Op amps, etc

Thread Starter

SamEricson

Joined Apr 25, 2015
196
yes true families, but why is there different families and why can't you interchange them even tho they are the same part number?

S= Schottky = 3nSec timing
ALS= Advanced LS = 4nSec timing
LS= Low power schottky = 10nSec timing
 

#12

Joined Nov 30, 2010
18,224
yes true families, but why is there different families and why can't you interchange them even tho they are the same part number?

S= Schottky = 3nSec timing
ALS= Advanced LS = 4nSec timing
LS= Low power schottky = 10nSec timing
1)There are different families of chips so chips in each family can be the best chip for different circuit requirements.
2)They are not the same part number. They have different letters in their part numbers.
3)Because each family is best at certain applications.
 

Thread Starter

SamEricson

Joined Apr 25, 2015
196
They are not the same part number. They have different letters in their part numbers.
Yes but i have seen techs for years just slapping in and interchanging different families because of the part number. I guess they thought they were the same even tho the family is different.

I think they only times it comes a problem is when you interchange logic IC chips of different families for address buss, control buss and data buss because of the timing issues
 

#12

Joined Nov 30, 2010
18,224
Either those techs really know what they're doing; or they don't know what they're doing. I'd tend to believe the latter.

Speed, fan in/out, threshold levels, ...; generally not interchangeable.
and we've come full circle again.
 

MrChips

Joined Oct 2, 2009
30,716
Either your techs know what they are doing or your techs don't know what they are doing. Period. (To quote someone before me.)

You cannot interchange across families unless you know what you are doing.

If you don't know the differences then don't interchange.
 

Thread Starter

SamEricson

Joined Apr 25, 2015
196
oh ok thanks mr.chips
I thought all this time a tech was able to interchange the different families
I know repair techs interchange families because they tell there clients they are "Upgrading" there circuit boards
 

dl324

Joined Mar 30, 2015
16,846
I know repair techs interchange families because they tell there clients they are "Upgrading" there circuit boards
I wouldn't call it an upgrade. It's a substitution that could cause the circuit to malfunction. I wonder how these techs you're referring to would spin that...
 

#12

Joined Nov 30, 2010
18,224
I wouldn't call it an upgrade. It's a substitution that could cause the circuit to malfunction. I wonder how these techs you're referring to would spin that...
They would charge the customer again, to install the correct parts (same as those which they took out). How to spin it? Just say it's a different problem that happened after the first bill was paid.
 

takao21203

Joined Apr 28, 2012
3,702
i hoped this ttl families syndicate had somehow vanished and with it students who memorize all the variants.

sometimes when a pinball machine is broken the board has worms, fix 5 errors, get more shortly, so, disable some creepy parts, and implant some controllers.

same with a microwave oven control board with so many parts, none needed, small controller does all.

74xx logic was used in ibm xt, and ibm at but that was about the time when they stopped using them.


there is single gate logic now so small ics i cant imagine how someone would want to test them.

Every decent GAL programmer can test TTL by the way.
 

takao21203

Joined Apr 28, 2012
3,702
What is some good IC chips that have a large library for every TTL, CMOS, Op amps . etc. to test IC chips in circuit
fix yor grammar too and try not to ask questions with no good answer.

its not even clear what you mean with testing, just functional, or all the parameters.
Thats not normally done.

you have a service manual, check the signals at test points, in case of doubt replace the ic.

oh i forgot jtag is often used for modern ics when testing is required but ttl/cmos didnt have that.
 

ian field

Joined Oct 27, 2012
6,536
There is no such thing as an IC chip that has a library of other chips inside it.
You will just have to do as you said in your second sentence.
Many many years ago, a hobby magazine suggested replaceable patch boards hooked up to test clips like:-

http://www.farnell.com/datasheets/54043.pdf

The Idea is to compare the signals present on the target logic chip with a known good sample on the patch board.

All the inputs on the patch board chip have to be connected to those on the target - then you verify that all the outputs are the same.

When I had the opportunity to dumpster dive at a computer end user disposals warehouse, I scored a big pile of 5 1/4" floppies that were libraries of TTL chips test parameters - someone else must've got the peripheral that goes with them while I wasn't looking!
 

takao21203

Joined Apr 28, 2012
3,702
there arent such ic testers on the mass market, be it ttl/cmos is aftermarket now, and the trend is digital processing.

there arent any cando all ics testers neither.

really old logic boards sometimes rely on the exact family while newer ones rather dont, only fanout plays a role, if any
 

dl324

Joined Mar 30, 2015
16,846
I know the IC testers get confused when testing the same IC part number but this identification list gets confusing for IC testers. I'm guessing it's called identification for say the 74H, 74L, 74s etc.
Unless testers are checking all of the device parameters, they shouldn't care. The logic function of all families is the same; they differ in power, speed, threshold, input/output load, etc.
 
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