Massive testing of 74xx and 40xx ICs: Are there any tester to build? - Page 1
Forum section: electronics / testgear

author: timofonic
author_rank: Frequent Contributor
timestamp: November 04, 2015, 12:08:01 pm
content: Hello.I need to test a lot of 74xx and 40xx ICs in my school and home. But I see too messy to make custom circuits for each IC.Are there some circuit to check them? I'm unable to locate one with enough visual information. I'm still a n00b, so no idea about programming but I can program a microcontroller.Thanks in advance.Kind regards.

author: HKJ
author_rank: Super Contributor
timestamp: November 04, 2015, 12:26:43 pm
content: Try searching for "logic ic tester" on ebay.

author: timb
author_rank: Super Contributor
timestamp: November 04, 2015, 12:29:04 pm
content: Do you need to test in circuit or out of circuit?In-Circuit: Get an old HP 10529A Logic Comparator on eBay. One can also be built with a handful of discrete XNOR gates or a CPLD. I actually built one out of a Cypress PSoC MCU!Out of Circuit: A TL599A EEPROM Programmer can test a lot of (but not nearly all) 74 Series chips.Sent from my Tablet

author: sorenkir
author_rank: Regular Contributor
timestamp: November 04, 2015, 12:36:00 pm
content: This programmer can test some logic ICs :https://www.eevblog.com/forum/blog/eevblog-411-minipro-tl866-universal-programmer-review/Michel.

author: EEVblog
author_rank: Unknown
timestamp: November 04, 2015, 12:36:06 pm
content: Wow, that reminds me of an IC tester I built 23 years ago now:And yes, you can still buy programmer that have IC testing functionality. Pretty cheap on ebay.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 04, 2015, 12:43:50 pm
content: Here's a reference:https://archive.org/details/radio_electronics_1985-09There's one that uses a Commodore 64 but who knows if you can find the software.

author: Fungus
author_rank: Super Contributor
timestamp: November 04, 2015, 12:53:13 pm
content: Quote from: Circuiteromalaguito on November 04, 2015, 12:08:01 pmGet aZIF socketand an Arduino. An Arduino can provide all the signals needed to drive those ICs. Add some LEDs for pass/fail. After that, well ... it's just software.

author: joeqsmith
author_rank: Super Contributor
timestamp: November 04, 2015, 01:30:48 pm
content: Quote from: Circuiteromalaguito on November 04, 2015, 12:08:01 pmMy old EETools AllMax+ will test them. I would think that most of the old programmers could do this. If you need something with an auto feeder, I would start checking eBay.

author: krivx
author_rank: Frequent Contributor
timestamp: November 04, 2015, 02:40:10 pm
content: Quote from: blueskull on November 04, 2015, 02:33:50 pmThe Alternatezone site? I don't think that was in any way secret

author: wn1fju
author_rank: Frequent Contributor
timestamp: November 04, 2015, 03:33:32 pm
content: I have one of those $30 Chinese IC testers (as already mentioned, search for "logic ic tester" on eBay) that I'm mostly happy with. It will test most, but not all, 7400 and 4000 chips. I've only found one case where it had a false positive and I haven't come across any false negatives (yet). A good thing to have lying aroundfor chips that are already out of circuit.

author: timofonic
author_rank: Frequent Contributor
timestamp: November 04, 2015, 05:03:35 pm
content: Quote from: HKJ on November 04, 2015, 12:26:43 pmQuote from: sorenkir on November 04, 2015, 12:36:00 pmQuote from: EEVblog on November 04, 2015, 12:36:06 pmQuote from: timb on November 04, 2015, 12:29:04 pmBut IC programmers require acomputerand I would need a standalone device. It can be okay if I can use it with my Arduino mobile phone.About the company that sells it: I heard they bounce emails. Does it mean they never reply? It would make me uncomfortable to buy an unsupported product, lacking repliable customer support.Why TL866 can't test all 74xx series? What about 40xx series?I would prefer to build it rather than buy it, it help me to improve my awful soldering and EDA skills. I know this is like vintage, but that's how they teach us digital electronics and I find it somewhat interesting.Quote from: timb on November 04, 2015, 12:29:04 pmI'm not sure. What are the possible use cases for? It seems interesting, I didn't know about that! Do you have more info? What's useful for?I would love to learn CPLD and FPGA after mastering this, of course.Quote from: Alex Eisenhut on November 04, 2015, 12:43:50 pmThat's funny! I love retrocomputing too! It can a nice small project and would be funny to show it to people and a self motivation exercise, I really neeed it!Coincidentally, there's a nice game named Robot's Odyssey for C64 that teaches boolean alebra with logic gates (both secuential and combinational)Quote from: EEVblog on November 04, 2015, 12:36:06 pmOh. Great! How did you build it? Would you like to make a nostalgic moment in some video?What about being a small project for you and Dave2? He deserves to appear in the channel too or make one for him. It can motivate the youngsters, just train him to be in good shape by moving all your oscilloscopes around and he will be stronger than a bullDo you have one about logic gates? You have tons of them and these days I'm not as active because some issues.

author: HKJ
author_rank: Super Contributor
timestamp: November 04, 2015, 05:13:12 pm
content: Quote from: Circuiteromalaguito on November 04, 2015, 05:03:35 pmIC programmers may need a computer, but logic IC testers do not.

author: bitseeker
author_rank: Super Contributor
timestamp: November 04, 2015, 10:15:41 pm
content: Quote from: blueskull on November 04, 2015, 05:32:18 pmHehe. He either meant an Android mobile phone, or it's one of his secret-to-make-millions Arduino projects.

author: timb
author_rank: Super Contributor
timestamp: November 05, 2015, 11:58:21 am
content: Quote from: Circuiteromalaguito on November 04, 2015, 05:03:35 pmThere are hundreds of different 74xx and 40xx series devices, from simple logic gates to counters, PLLs, static RAMs and more, some of which would be next to impossible to test without external components. The ones that can be tested are still a wildly varied assortment!In my experience, most of dedicated logic IC testers on eBay are next to worthless. Programmers like the TL866 et al are better, but they require a computer. They can also test a wider assortment of ICs and do more thorough tests, precisely because of that! (The test patterns aren't stored in the device itself, instead just uploaded on the fly when you hit the test button.) Just get an old netbook for $25-50 to use with the thing, problem solved!As for in-circuit testers like the HP Logic Comparator: Say you're repairing an old board and you've narrowed the failure down to a specific area; maybe you want to be sure a particular IC is bad before you desolder it. You take a known good IC of the same type, put it in the Logic Comparator and then place the IC clip on the suspected bad chip.Let's say it was a 74L00N; now, the input signals will go to both chips at the same time. The outputs of both chips will be fed through an XOR gate; if the outputs are both the same, none of the LEDs will light. However, if one or more of the outputs are different the corresponding LED will light up! Clever, right?I built a version of this using a Cypress PSoC MCU. I used the FPGAish portion to implement common 74xx series logic functions like AND, NOT, NOR, OR, etc. gates, buffers and counters and internally XOR'd them with external inputs.So it basically works like a standalone logic comparator. I just clip it to the suspect IC and use a button to scroll through a list of of 74xx series chips to emulate on a little OLED display. During operation the display shows schematic like symbols of the gates and their logic status (1, 0 or Z) preceded by an equal or not-equal sign.By itself, this homebrew device has saved me hundreds of man hours fixing vintage test gear. (Other super useful gear you can pry from my cold dead hands are my HP 546A Logic Pulser, 545A Logic Probe, 548A Logic Clip and 547A Current Tracer. The current tracer and Pulser especially!)Sent from my Smartphone

author: timofonic
author_rank: Frequent Contributor
timestamp: November 05, 2015, 10:51:50 pm
content: Quote from: bitseeker on November 04, 2015, 10:15:41 pmYou're right! I have a secret plan to make million and do a hostile takeover to EEvBLOG! Instead the videos being done by an aussie, the videos will be done by a Spaniard in broken (but still improving) EnglishMy mobile phone did something wrong with text prediction and wrote this very fastly, so I didn't check the text after writing it. Of course, I meant the damn Android.But using an Arduino or maybe a RaspberryPi-like board isn't a bad idea too! It can be used for other equipment without needing to switch cables and share a big TFT panel for all them. It would be like my own LCARS electronics geek consoleAny ideas? I would love your comments, pleaseQuote from: timb on November 05, 2015, 11:58:21 amThat's an interesting approach. An old netbook can be a nice addition to my future portable lab, it can be used while I'm able to get a proper fast laptop.An smaller ARM board with touch screen and optional keyboard might be interesting too, but more cumbersome. I would prefer to use electronics FOSS all time, but sometimes I'm forced to use shit like Circuit Wizard.Quote from: timb on November 04, 2015, 12:29:04 pmIt seems quite interesting! I didn't know about that!Quote from: timb on November 04, 2015, 12:29:04 pmWould you release your project as OSHW or we need to pry from your cold dead hands too?