Any idea what this IC is? - Page 1
Forum section: electronics / general

author: Rick Law
author_rank: Super Contributor
timestamp: October 10, 2020, 09:58:07 pm
content: Trying to identify an unknown IC. This is on the "user interface" board of a dish washer. The ruler scale is cm.I suspect this is the MCU. Searching the markings "7082zb0b rf2135cmn" found nothing.Thanks

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 10, 2020, 10:06:05 pm
content: The part number format appears to be Renesas. If you can't find documentation on their site, it might be customized for the appliance or appliance subassembly manufacturer.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 10, 2020, 10:07:26 pm
content: You forgot the 5https://pdf1.alldatasheet.com/datasheet-pdf/view/683718/RENESAS/R5F2135CMNFP.htmlR8 looks... broadly comparable to MSP430, say, midway between AVR and ARM? Looks to be a Flash model so it should be reprogrammable, if you so dare; is probably locked by the factory so you can't download it, at least not trivially (but there are often bugs that can be abused to read out program data.Or if it's completely toast... just get a new board, you'll need a new one anyway to copy the firmware from (if you can copy it at all).Tim

author: Rick Law
author_rank: Super Contributor
timestamp: October 11, 2020, 10:24:15 pm
content: Quote from: T3sl4co1l on October 10, 2020, 10:07:26 pmGeez! I did missed a 5. I did my search by typing that with notepad first, and copied/pasted different combinations to search. Of course, every time I searched by pasting, I missed that damn 5.I was suspecting it may be the MCU, thanks for the confirmation.I purchased and installed a new board from the manufacturer already. So that dishwasher has risen from the dead for about a week now. But in my initial research into the problem, that user interface board appears to be the "frequent failure" module. So post repair I was studying the bad one to see if I found anything interesting. Finding out what MCU is more to satisfy a curiosity.I know an MCU failure will require firmware that I won't have. Had I observed some other obvious failure, I would try to repair this failed board as a stand-by for next time since this is the "frequent failure" module. But I saw nothing obvious on it. I was hoping to see a blown fuse on the board or something simple like that, but no such luck...

author: magic
author_rank: Super Contributor
timestamp: October 12, 2020, 05:44:08 am
content: Capacitors and voltage regulators?

author: Rick Law
author_rank: Super Contributor
timestamp: October 12, 2020, 08:05:01 am
content: Quote from: magic on October 12, 2020, 05:44:08 amThat's what I thought too. I did mapped out where and what the voltage regulator is - it is a 78L05B, 5V SO8 package. The 100mA this guy can put out is less than I expect for the board, but with just a few tac switches, 10 to 15 smd-led indicators that perhaps only 10 are on at any one time, and a 3x7 segment cycle-timer display, 100mA looks possibly adequate. That power regulation circuit possibly is the power supply to the entire board. Externally supplying power to the board doesn't fully boot but do show some signs something is going on.I don't want to write a 2 page details - in a nutshell, the good board needs proper connection to the machine to match the jumper selected model information before it will complete the boot, otherwise it acted pretty much like the bad one. So I need the bad one to be connected to the machine in order to test if it boots with external power to the board (there by confirming it is a power issue.)But to do that, two issues I must figure out:1. I know when externally powered, the bad board is doing something since current drawn is changed when I presses some switches. Powering a removed board externally is one thing. Powering it externally when connected to the rest of the machine puts the rest of the machine at risk. At 100mA max external power, I think it should be too small to cause possible harm. But I don't know for sure.2. Most of the work is in moving the machine out, taking out the door, taking the door apart, taking the electronic housing apart, now I can get to the board. And then there is putting everything back together when done. That means testing would disrupt the entire kitchen and will take almost an entire day. I have to figure out if I can find an easier way to test that. After confirming it is a power failure, I still need to test the fixed board probably more than once. Fully disassembly and reassembly in tiny space (like disconnect/reconnect things under the machine) do take a toll on my aging body these days.I think #2 is a bigger one issue. I mustfirstfigure out how to test this without creating a big disruption in the kitchen and a heavy toll on my body. Fixing this bad board is but just a challenge I like to meet and largely for fun and personal satisfaction. But multiple day long disruptions in the kitchen (and probably with my wife getting on my case) is hardly fun and hardly personally satisfying.Not-decided yet...