Help with diode identification, Inverter board - Page 1
Forum section: electronics / repair

author: docbob
author_rank: Newbie
timestamp: May 23, 2021, 03:41:55 am
content: Part # is 02 03. One set of numbers is Horizontal and the other is Vertical, depending on how you read it.The picture shows only one digit from each number 2 0 (the middle two digits). It doesn’t show the first 0 or the ending 3 digit. What you can see is 2 0, see how they are not in the same direction…This diode is in an HVAC inverter board. Any help would be great!ps the diode line is like a bunch of less-than symbols, maybe that identifies the manufacture??... Additional information on the diode:Daikin HVAC inverter board 2P179362 3PCB1560. Diode is D5 on this PCB.Thanks for any help you can provide.

author: bob91343
author_rank: Super Contributor
timestamp: May 23, 2021, 04:09:28 am
content: I believe the symbols identify the cathode end. If it's on a HVAC board it's probably a simple 1N4005 or similar.

author: docbob
author_rank: Newbie
timestamp: May 23, 2021, 04:42:15 am
content: Thanks bob91242,The diode anode side goes to a small transformer and the cathode goes to a 25v 470uF electrolytic capacitor. Someone thought it was a MUR410 (Ultra fast diode), but that is WAY too big, size not even close.I thought inverters use at least fast switching diodes, I think 1N4005 is for general rectifying... I know the symbols mean cathode but it is normally a white line, so I was thinking it might identify the manufacture, so I had hoped.

author: bob91343
author_rank: Super Contributor
timestamp: May 23, 2021, 05:53:20 pm
content: I didn't realize there was an inverter there. If so, that may be a Schottky diode, although those don't have high breakdown voltages.

author: docbob
author_rank: Newbie
timestamp: May 23, 2021, 07:24:17 pm
content: I did try those MUR410 diodes, but the board didn't power up.

author: RayRay
author_rank: Frequent Contributor
timestamp: May 23, 2021, 07:51:05 pm
content: Uh, what am I looking at here? Did you really cut off the original diodes, left the legs in, and soldered the new ones into em? That's not the proper way of doing this type of work (although, it'd work just as good from a technical prespective) but really, you should've just desolderedd em. As far as the original question goes though, it's hard to identify it from the given pic. If you could make a video (showing a slow spin/twirl of it, under good light) it might help.

author: docbob
author_rank: Newbie
timestamp: May 23, 2021, 11:14:33 pm
content: For what it's worth ... the original diodes were very small (no legs and flat on the pcb), they were desoldered and tested. The new diodes (very large) would not fit in the holes, pins too large. To make it fit without enlarging the holes and damaging a multi-layer board, I used smaller pins (high temp solder) to raise the new big diodes so they would fit within the components on the board. New connections then were tested for conductivity (following best practice).On another note: I thought it could be schottky as well bob91343. Thx!If anyone has additional info on those diodes, it would be much appreciated!!

author: docbob
author_rank: Newbie
timestamp: May 23, 2021, 11:30:19 pm
content: More Pics:

author: RayRay
author_rank: Frequent Contributor
timestamp: May 24, 2021, 12:35:22 am
content: Quote from: docbob on May 23, 2021, 11:14:33 pmTested with a multimeter in diode mode I presume? Anyhow, you shouldn't have even attempted that swap IMO.Each diode can carry up to X amount of current (and the diameter of the leads is determined accordingly by the manufacturer) so if a diode doesn't physically fit into the holes, it's not suppose to, and you should never try to wing it. Try 1N4007 and see how that goes. Worst case scenario, you could just get a full board replacement from aliexpress:https://www.aliexpress.com/item/1005001436945702.htmlA bit on the pricey side (but way cheaper than the ebay sellers of this board), also, do note that there seems to be two versions of it (-1 or -2 in the end). Have you tested the fuses btw? And sorry, the original diode is pretty much unrecognizable from the markings (and I couldn't find anything on Google for it, nor any kind of service manual mentioning that specific board)

author: docbob
author_rank: Newbie
timestamp: May 24, 2021, 01:34:10 am
content: Yup, I saw those on aliexpress, the price is not bad compared to what everyone else is selling them for. Fyi, I'm doing this for free for a friend, so the budget is low to zero.Ok, I know how diodes work ... after researching I found a very kind soul on youtube:After emailing the gentleman, a Daikin HVAC repair service tech and discussing the size and diode specifications, he assured me he has fixed many of these boards by replacing the diodes with MUR410, this is the only reason it was attempted... So, I did my due diligence before making any modifications. Yes of course I checked all the fuses, and I know how to test diodes, I even check its signature with my Huntron, just for fun. The board is version "2", however I believe version one and two are compatible. Thanks for the google searching RayRay.No one has seen these little less-than symbols on a diode before??

author: RayRay
author_rank: Frequent Contributor
timestamp: May 24, 2021, 01:14:21 pm
content: Well, "many of these boards" doesn't necessarily mean that your specific one is included. If the original diode is physically much smaller, and with smaller leads, then it's most likely a smaller current one (1A OR 2A). You could try 1N4007/RL207, or contacting Daikin directly and see if they can assist you. And no, there's absolutely no diode called 0203 (it's either custom made, or poorly labelled) Also, I think you might be a bit too naive here. You seem to think that replacing that one diode would fix things (which may or may not be the case) because there's a strong possibility that there are additional components that have also gone bad! My advice, try what I mentioned^, no go, then tell your friend to order a replacement board and get it done with (he could also pay extra for premium/expiedited shipping, if he needs it urgently) Testing the other components can be quite time consuming, you may or may not have the equipment required to do so, and given the fact you're doing him a favor, I don't think it's really worth your time.

author: docbob
author_rank: Newbie
timestamp: May 24, 2021, 02:13:33 pm
content: Rayray, I'm just making sure the diode is the correct one, and I have tested other components, and ... I'm keenly aware of what board I have, oh boy.... I just posted here in hopes to get a little insight into the manufacture of a diode, nothing more, and clearly I appreciated some of the information I received, however I did not come here to get insulted, no more "advice", I'm done, thanks a bunch, I shall look elsewhere.FYI, He is afriend, you do things for friends for free, or at least I do, that's what friendship is!

author: RayRay
author_rank: Frequent Contributor
timestamp: May 24, 2021, 02:34:45 pm
content: When exactly did I insult you? You're overly-sensitive IMO. But no, friendship is not letting a friend take advantage of you in any shape, way or form! There's a difference between being a nice person and being a doormat. Nothing wrong with doing a friend a favor, but if it's something very time consuming (and they're not paying you) I wouldn't go the extra mile, that's my opinion anyway. And I'm not suppose to guess you've checked all the other components. but anyhow ,good luck.