Help identifying this diode from IBM PC 220v power supply - Page 1
Forum section: electronics / beginners

author: Slaanesh
author_rank: Newbie
timestamp: March 18, 2025, 09:49:13 am
content: There are 4 lines of text wrapped around the barrel of the diodeNot sure which line is the beginning - this is my interpretation of the characters (in order around the barrel):429142TTTSee the four attached photosThe diodes are close to a transformer several directly on circuit.Any idea? Any ideas appreciated.

author: Alex_Baker
author_rank: Frequent Contributor
timestamp: March 18, 2025, 04:11:54 pm
content: Can you post an image of the surrounding circuit? some context may be useful.

author: Konkedout
author_rank: Frequent Contributor
timestamp: March 18, 2025, 04:29:16 pm
content: Quote from: Alex_Baker on March 18, 2025, 04:11:54 pmI agree. If you can draw the circuit diagram of the components around the diode it might also help. Here are a few educated guesses:1) P/N signal diode such as 1N914 or 1N4148. The 1N4148 is the newer number but those two are mostly interchangeable. Those are cheap and represent the most likely single option. So if you cannot figure out anything else, then AS A LAST RESORT you could just try substituting in one of those. When our dishwasher died a few years ago, I found what looked like a physically blown transistor... I could not identify any component markings. With nothing to lose, I tried something from my stock. AND..........!!!!!!!!! it did not work. Ahh, well...2) Zener diode. For a zener diode, it would be important to figure out the original zener voltage.3) Maybe less likely: A small signal schottky diode. Here are some possibilities:https://www.digikey.com/en/products/filter/diodes/rectifiers/single-diodes/280?s=N4IgjCBcoGwJxVAYygMwIYBsDOBTANCAPZQDaIALGGABxwDsIAuoQA4AuUIAyuwE4BLAHYBzEAF9CAVnoAGRCBSQMOAsTKVZsgMz0azNp0g9%2BwsZJBwwFBUpV5CJSOTBwATHCkwQhN-XpwNDaEMDQ02to%2B4FraOlHWslSMLCAcXLyCohKEALRutlD8AK5qTuRSzOJVQA

author: fzabkar
author_rank: Super Contributor
timestamp: March 18, 2025, 04:50:44 pm
content: I suspect "TTT" may be "ITT". That's the manufacturer.

author: Kharn_the_Betrayer
author_rank: Contributor
timestamp: March 18, 2025, 06:51:04 pm
content: Do you have the model name for the power supply? That could also give some clues.

author: Slaanesh
author_rank: Newbie
timestamp: March 18, 2025, 08:23:04 pm
content: Hey thanks for the repliesHere are some additional photosJust north of the transformer you can see where they originally resided CR1, CR2, CR16 and CR17 … but CR2 was already broken.I tested one in my component testerThe board is 204-1041M from a 220/240v power supplyThe last photo shows the transformer removed to clean under it as the RIFA caps had blown and some potential proxy diodes in place - but these are the wrong type so ignore them

author: fzabkar
author_rank: Super Contributor
timestamp: March 18, 2025, 09:28:27 pm
content: It looks like the vintage is 1984.Is this too early?https://bitsavers.org/components/itt/_dataBooks/1974_ITT_Semiconductor_Product_Catalog.pdfIC1 (221-233) is equivalent to NTE1672:https://www.sourceresearch.com/store1/quickstore.cfm?ProductID=53118&do=detailhttps://web.archive.org/web/20030417051253/http://www.nteinc.com:80/specs/1600to1699/pdf/nte1672.pdf(datasheet)If the diodes are associated with it, then perhaps a reverse search against NTE's part number will turn up the original part. The original part may have an application circuit in its datasheet.IC1 appears to be a TDA1060:https://datasheet.octopart.com/TDA1060T-NXP-Semiconductors-datasheet-180996855.pdfFYI ...221-129 = NTE987 (quad op amp)221-121 = NTE834 (quad comparator)https://web.archive.org/web/20210914064337/https://doc-0o-8k-docs.googleusercontent.com/docs/securesc/5r43psth469g5c1rftpmn0nppq5phemg/2opgu28r7auisrnejo2aei805h27lola/1631601750000/17694043826446093949/05678510092086807988Z/0B2FO5ud-l4eiVXFSQlR0LWsxWXM?nonce=1gvcgcsff3cos&user=05678510092086807988Z&hash=nokhdenc5dlu5sbb3squmha5lmga8ugc(NTE834)https://web.archive.org/web/20040715212659/http://www.cedmagic.com:80/tech-info/data/nte987.pdf(NTE987)

author: Slaanesh
author_rank: Newbie
timestamp: March 18, 2025, 11:51:58 pm
content: Very useful information so far, thank you.So the diode is from ITT so would it make sense that the order of infoITT429142I see that ITT make a 1N4429 rectifier but I'm only speculating. I modern replacement is 1N4007.Does anyone know about the numbers and even which order they should be read?Anyway I'm looking at the data sheet TDA1060 and see what info that yields.