lm328 tester killed - Page 1
Forum section: electronics / repair

author: p.larner
author_rank: Frequent Contributor
timestamp: September 24, 2023, 03:17:30 pm
content: Long story but i was testing some caps for leakage using an old hunts orb condensor tester from about 1945(magic eye version),after that i decided to stick one on my lm 328 led component tester,like a fool i forgot to charge the cap!,there was a spark when i connected said cap now the tester is dead,any idea if its fixable,if so where to start?,not a big issue as they are cheap,it just would be good to get it going again tho,at the moment its dead and the lcd display has no illuminaton and is blanc.

author: Ian.M
author_rank: Super Contributor
timestamp: September 24, 2023, 04:24:57 pm
content: Just about all '328 three terminal component testers use a similar circuit, with the test pins going direct to its ATmega328P MCU 'brain' (+ to a resistor network connected to the MCU). Odds are close to 100% you've zapped the MCU, and replacement with acorrectly programmednew one will fix it. However before doing that you should check the 5V supply, (which may be being pulled down by a failed MCU).See:https://www.eevblog.com/forum/beginners/atmega328-component-tester-killed-with-400v-cap/and the mega-thread on '328 component testers:https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/

author: p.larner
author_rank: Frequent Contributor
timestamp: September 25, 2023, 03:58:36 am
content: Thanks ian,i suspected that,would it of killed the lcd too?,ive ordered a new tester but just wondered.

author: Ian.M
author_rank: Super Contributor
timestamp: September 25, 2023, 04:29:30 am
content: Its hard to say - hook it up to an Arduino, find a library for whatever model display it is, and try the library's demo examples.The display is on different pins to the component test ones, so it is less likely to have been damaged directly, but if the 5V rail spiked too high it could have blown it.

author: p.larner
author_rank: Frequent Contributor
timestamp: October 14, 2023, 01:07:06 am
content: just an update on this,i ordered an identical kit,i built it using my old display from the dead tester,it works ok,is there anyway to clone a 328 ic,or suck its fw?.

author: Ian.M
author_rank: Super Contributor
timestamp: October 14, 2023, 03:45:28 am
content: The ATmega328P in the kit *shouldn't* be protected because its based on an open source project:https://www.mikrocontroller.net/articles/AVR_Transistortesterbut some manufacturers are ar5eholes and turn on protection anyway, making the chip virtually impossible to clone. However, odds are you can find a firmware version at the above site that will work.In all cases you'll need an AVR programmer + software to run it. This could be as cheap and simple as an Arduino running the ArduinoISP sketch, + the command lineAVRDUDE, or could be a full-featured universal programmer with its own GUI software or anything in-between.

author: p.larner
author_rank: Frequent Contributor
timestamp: October 15, 2023, 07:41:37 am
content: so how do i copy the fw from the new 328 ic?

author: kripton2035
author_rank: Super Contributor
timestamp: October 15, 2023, 07:53:33 am
content: seeing the price of these transistor-led-everything testers nowadays, it would be simplier to buy a new oneit will cost you the same price if not more in programming devices to TRY to repair it !

author: Ian.M
author_rank: Super Contributor
timestamp: October 15, 2023, 08:02:30 am
content: That depends on which AVR programmer you have. If its intended for in-circuit programming and your component tester doesn't have a six pin AVR ISP header, you may also need a breadboard, and some jumpers and possibly a 100nF disc ceramic capacitor (for Vcc decoupling). Basically you need to hook up the ATmega328P Gnd, Vcc, /Reset and all the SPI pins to your programmer and run its software, then read the FLASH (program memory), EEPROM and FUSES, which may be separate operations.As I mentioned earlier, an Arduino programmed with the ArdinoISP sketch can be used, with this hookup:If your programmer uses AVRDUDE, you may find AVRDUDESHELL useful to let you run it from a GUI rather than the command line.http://matrex-notes.blogspot.com/2015/01/avrdudeshell-atmega.html

author: p.larner
author_rank: Frequent Contributor
timestamp: October 15, 2023, 08:49:47 am
content: thanks for the replys but you seem to be missing the point,i want to read the fw from the working 328 not rite to it!,is that possible even?.

author: Ian.M
author_rank: Super Contributor
timestamp: October 15, 2023, 09:05:16 am
content: The hardware setup and equipment needed to read the chip is exactly the same as that to write (program) it The only difference is the actions you use the programmer software to perform.