1 Sep
2007
1 Sep
'07
9:29 p.m.
Before I write to the group, Kurt Klemm, if you read this please try
sending me a message on my web forum at http://www.stockly.com I am
getting your e-mails but based on them it sounds like you are not
getting mine! : (
--- Now to the rest:
I'm wishing I've kept all the broken TTL chips over the years...
I am evaluating a TOP2004 programmer for testing TTL chips. I bought
it off of ebay from
http://www.mcumall.com/comersus/store/comersus_dynamicIndex.asp I
bought it on ebay because the price was cheaper. They are located in
Canada and it took 5 days to get shipped to Alaska. Very well
packed. The other TOP programmers ship from china/japan.
I want to be able to recommend a TTL tester to my customers of the
Kenbak kit. With 132 74xx TTL chips it would really come in handy!
So far I think it does a good job. If I lift a signal leg on a
74LS04 it both can't auto detect anything and will report a 7404 as
bad. I only have one known bad part, a 74LS376. It DID report it as
bad and undetectable.
What I'm wondering is if anyone knows how I can prematurely kill a
TTL device or simulate static failure. I'd like to try to test how
thoroughly the programmer tests the chips. It can't tell the
difference between a 7410 and 7412, but that isn't too important for
knowing the chip works (mostly)
On a second note, I have successfully over clocked my Kenbak
500%. Its running happily at 5MHz. : ) Although it gets a lot
hotter! I need heat sinks...
--I suppose giving one 12v to simulate hooking up a power supply wrong?
--Hooking 12v to a device normally powered at 5v?
--Shorting out a buffer output? (I think some buffers are designed
to be shorted out though)
--Vehicle ignition coil to an input? : D
Grant
1 Sep
1 Sep
9:42 p.m.
Awhile back, perhaps early '80s, there was a paper or monograph from
Tektronix which discussed affects of ESD on TTL. Many people believe(d)
that ESD can damage or destroy MOS parts, but that there is no effect on
TTL parts.
The above publication claimed differently. Stated that although ESD does
not destroy TTL function, immunty to noise and (IIRC) switching speeds
are impacted because of damage to gate structures.
Steve
Grant Stockly wrote:
Before I write to the group, Kurt Klemm, if you read
this please try
sending me a message on my web forum at http://www.stockly.com I am
getting your e-mails but based on them it sounds like you are not
getting mine! : (
--- Now to the rest:
I'm wishing I've kept all the broken TTL chips over the years...
I am evaluating a TOP2004 programmer for testing TTL chips. I bought
it off of ebay from
http://www.mcumall.com/comersus/store/comersus_dynamicIndex.asp I
bought it on ebay because the price was cheaper. They are located in
Canada and it took 5 days to get shipped to Alaska. Very well
packed. The other TOP programmers ship from china/japan.
I want to be able to recommend a TTL tester to my customers of the
Kenbak kit. With 132 74xx TTL chips it would really come in handy!
So far I think it does a good job. If I lift a signal leg on a 74LS04
it both can't auto detect anything and will report a 7404 as bad. I
only have one known bad part, a 74LS376. It DID report it as bad and
undetectable.
What I'm wondering is if anyone knows how I can prematurely kill a TTL
device or simulate static failure. I'd like to try to test how
thoroughly the programmer tests the chips. It can't tell the
difference between a 7410 and 7412, but that isn't too important for
knowing the chip works (mostly)
On a second note, I have successfully over clocked my Kenbak 500%.
Its running happily at 5MHz. : ) Although it gets a lot hotter! I
need heat sinks...
--I suppose giving one 12v to simulate hooking up a power supply wrong?
--Hooking 12v to a device normally powered at 5v?
--Shorting out a buffer output? (I think some buffers are designed to
be shorted out though)
--Vehicle ignition coil to an input? : D
Grant
9:46 p.m.
Should have been "effects of ESD on TTL"; prdn.
Steve Stutman wrote:
Awhile back, perhaps early '80s, there was a paper
or monograph from
Tektronix which discussed affects of ESD on TTL. Many people
believe(d) that ESD can damage or destroy MOS parts, but that there is
no effect on TTL parts.
The above publication claimed differently. Stated that although ESD
does not destroy TTL function, immunty to noise and (IIRC) switching
speeds are impacted because of damage to gate structures.
Steve
Grant Stockly wrote:
Before I write to the group, Kurt Klemm, if you
read this please try
sending me a message on my web forum at http://www.stockly.com I am
getting your e-mails but based on them it sounds like you are not
getting mine! : (
--- Now to the rest:
I'm wishing I've kept all the broken TTL chips over the years...
I am evaluating a TOP2004 programmer for testing TTL chips. I bought
it off of ebay from
http://www.mcumall.com/comersus/store/comersus_dynamicIndex.asp I
bought it on ebay because the price was cheaper. They are located in
Canada and it took 5 days to get shipped to Alaska. Very well
packed. The other TOP programmers ship from china/japan.
I want to be able to recommend a TTL tester to my customers of the
Kenbak kit. With 132 74xx TTL chips it would really come in handy!
So far I think it does a good job. If I lift a signal leg on a
74LS04 it both can't auto detect anything and will report a 7404 as
bad. I only have one known bad part, a 74LS376. It DID report it as
bad and undetectable.
What I'm wondering is if anyone knows how I can prematurely kill a
TTL device or simulate static failure. I'd like to try to test how
thoroughly the programmer tests the chips. It can't tell the
difference between a 7410 and 7412, but that isn't too important for
knowing the chip works (mostly)
On a second note, I have successfully over clocked my Kenbak 500%.
Its running happily at 5MHz. : ) Although it gets a lot hotter! I
need heat sinks...
--I suppose giving one 12v to simulate hooking up a power supply wrong?
--Hooking 12v to a device normally powered at 5v?
--Shorting out a buffer output? (I think some buffers are designed
to be shorted out though)
--Vehicle ignition coil to an input? : D
Grant
10:17 p.m.
The above publication claimed differently. Stated that
although ESD does
not destroy TTL function, immunty to noise and (IIRC) switching speeds
are impacted because of damage to gate structures.
Long term reliability also takes a hit, even if noise immunity and
speed are not impacted.
--
Will
10:18 p.m.
At 05:42 PM 9/1/2007, you wrote:
Awhile back, perhaps early '80s, there was a paper
or monograph from
Tektronix which discussed affects of ESD on TTL. Many people
believe(d) that ESD can damage or destroy MOS parts, but that there
is no effect on TTL parts.
The above publication claimed differently. Stated that although ESD
does not destroy TTL function, immunty to noise and (IIRC) switching
speeds are impacted because of damage to gate structures.
I thought static could poke holes in (that might have been a simple
description) or separate PN / NP junctions which in the end didn't
impact function but current capacity. I think this was specifically
talking about mosfets.
Grant
10 p.m.
Grant Stockly wrote:
What I'm wondering is if anyone knows how I can
prematurely kill a TTL
device or simulate static failure.
Well Just look for the MAGIC SMOKE floating around the room,
ITS DEAD JIM :)
I'd like to try to test how
thoroughly the programmer tests the chips. It
can't tell the difference
between a 7410 and 7412, but that isn't too important for knowing the
chip works (mostly)
From what I remember reading about bad chips is that they did not meet
AC measurements not DC ones. The flip/flop works great a 1 MHz but not
20Mhz like the spec sheet states.
On a second note, I have successfully over clocked my
Kenbak 500%. Its
running happily at 5MHz. : ) Although it gets a lot hotter! I need
heat sinks...
God what next ... 12 bits?
Ben alias woodelf
10:06 p.m.
--- Grant Stockly <grant at stockly.com> wrote:
I'd like to
try to test how
thoroughly the programmer tests the chips. It can't
tell the
difference between a 7410 and 7412, but that isn't
too important for
knowing the chip works (mostly)
Note that cheap IC testers are just truth-table
checkers. They cannot identify parts that are
out of their rated electrical specs, but which
can still drive the load provided by the tester
to an acceptable logic level. They are no good
for checking timing characteristics, input loading,
output drive, etc. This is one reason why such
testers cannot distinguish, say, between ordinary
gates and logically-equivalent buffers. Similarly,
they cannot identify parts that need external
components to operate, such as one-shots.
As such simple testers go, I have one of these,
which is conveniently self-contained:
http://www.elexp.com/tst_100.htm
The device is called the "Leaper-1" and is
sold widely, but Electronix Express has the
best price that I could find.
An advantage of a PC-based tester, such as the
testing function on a device programmer,
is that some will let you program your own test
vectors.
--Bill
10:59 p.m.
As such simple testers go, I have one of these,
which is conveniently self-contained:
http://www.elexp.com/tst_100.htm
The device is called the "Leaper-1" and is
sold widely, but Electronix Express has the
best price that I could find.
That is the exact device I'm going to buy next. Can it tell the
difference between a 12/10 or a bad 10 to a good one? Have you ever
found a chip that tested good but was bad?
An advantage of a PC-based tester, such as the
testing function on a device programmer,
is that some will let you program your own test
vectors.
This one can't do custom vectors I think. Its a cheap made in china
device. I thought that I could have a recommendation for a cheap and
expensive device. Also being able to program/read EPROMs and
microcontrollers was a point in favor of the cheap TOP2004.
I did just find a bad 7400 in my pile of "tainted" chips. : ) It
wouldn't detect as anything.
The worst thing to have is a false positive. I would much rather
have a tester that returned false negatives.
Grant
10:33 p.m.
--I suppose giving one 12v to simulate hooking up a
power supply wrong?
--Hooking 12v to a device normally powered at 5v?
--Shorting out a buffer output? (I think some
buffers are designed
to be shorted out though)
--Vehicle ignition coil to an input? : D
Reverse ground and +5v
Clock an input way too fast
Heat it up far too much (soldering iron/heat gun)
Microwave oven.
Shufffle....shuffle...shuffle..shuffle....ZAP!
Or, of course, to make things appear dead or damaged,
all you need to do is manually short an input or
output to ground with a wire.
Some chips are suprisingly resiliant. I once tried to
kill a mask PROM on purpose using static electricity.
It took at least three or four good zaps to kill it.
-Ian
10:55 p.m.
Hand it over to a college administator?
or a professor of "Computer Science"?
give it a fixed term warranty?
11:25 p.m.
Mr Ian Primus wrote:
Some chips are suprisingly resiliant. I once tried to
kill a mask PROM on purpose using static electricity.
It took at least three or four good zaps to kill it.
Wonders if I have any old TTL to toss in the toaster ???
So far I tend to toast transistors in a high voltage ( 300 Volt)
power supply.
-Ian
PS. Any body got a good schematic for a low
noise 300 volt 220 ma
power supply with low ripple.
2 Sep
2 Sep
10:23 p.m.
Ian Primus wrote:
Some chips are suprisingly resiliant. I once tried to
kill a mask PROM on purpose using static electricity.
It took at least three or four good zaps to kill it.
Aw, Ian, if you're serious about this, you need your own HiPot. Lots
of fun trying to zap operation pieces of equipment with one.
Or build your own Marx generator, for even more spectacular results:
http://www.electricstuff.co.uk/marxthree.html
Cheers,
Chuck
11:21 p.m.
Chuck Guzis wrote:
Or build your own Marx generator, for even more
spectacular results:
http://www.electricstuff.co.uk/marxthree.html
Well that is fun, but right now I am planning to toast
transistors. I plan to build a 300 volt power supply @ 230 ma
but the transformer under line high conditions is 415 volts.
All the transistors I can find easily are 400 vceo.
Ben alias woodelf
PS. All the heatsinks I can find are good to 5 watts.
I need about a 30 watt heat sink... Sigh.
5:14 p.m.
What I'm wondering is if anyone knows how I can
prematurely kill a
TTL device or simulate static failure. I'd like to try to test how
thoroughly the programmer tests the chips. It can't tell the
difference between a 7410 and 7412, but that isn't too important for
knowing the chip works (mostly)
IIRC, the 7410 is a triple 3-input NAND gate (totem pole outputs), the
7412 is the open-collector version. If it can't tell those apart, how can
it reject a 7410 where one or more of the 'top' transsitors in the totem
pole output have failed? And yes, I've had that failure mode (actually in
74H series devices).
FOr that matter can it tell if 3-state outputs are working correctly
(rather than, say, being stuck high when they should be disabled)?
If you twant to simulate simple failures, how about wiring the IC to a
DIL header with one or more pins open-circuited (and maybe tying pins
that should be outputs to ground rather than to the output pin of the chip).
-tony
6148
days inactive
6149
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