Dishwasher power board - Page 1
Forum section: electronics / repair

author: AndyPen1981
author_rank: Contributor
timestamp: December 29, 2024, 09:56:16 pm
content: Hi, I have a Lamona dishwasher pcb with a blown chip, the top of the chip has gone so there are no numbers to referenceI've looked online and found the same pcb for a different make of dishwasher ( BEKO) and noted chip type to be a LNK364PNThis pcb is obsolete and not available to buy anywhere, so I decided to try and fix it myself.My question is, are there any compatible chips that I can use instead the LNK364PN that I can just drop in without modification, the reason I ask is I have a few boards with chips, one being the LNK306PN which may be compatible according to Google but I'm not 100% sure. The other chips don't have numbers begging with LNKSo far I have found a shorted diode and a blown chip, I haven't tested furtherThanks for any help or information

author: Zero999
author_rank: Super Contributor
timestamp: December 29, 2024, 10:37:47 pm
content: I searched for the datasheet for the LNK306PN and no, it's completely different to the LNK364PN.https://docs.rs-online.com/3734/0900766b815f08d8.pdfhttps://www.mouser.co.uk/datasheet/2/328/lnk362-364-1511784.pdfWhy not simply buy a replacement LNK364PN? Mouser sells them. I haven't looked elsewhere, but no doubt there are other distributors who stock them.https://www.mouser.co.uk/ProductDetail/Power-Integrations/LNK364PN?qs=WS5Jv%252B%252Bx1qX9GBs6vD0%2Fsw%3D%3D&srsltid=AfmBOooNqoM20IxPbViAu0V62RyrNu53EJtK85UWAGAJ2fBxPjw0X8UC

author: AndyPen1981
author_rank: Contributor
timestamp: December 29, 2024, 10:57:54 pm
content: now that my alternative chip has been ruled out 😄 I will order one from somewhere tomorrow.Thanks for the help, I only dabble with this kind of stuff when the chance arises therfore I'm not good at cross referencing data sheets etc.. but I can by with a little help 👍

author: inse
author_rank: Super Contributor
timestamp: December 30, 2024, 03:34:56 am
content: I have been dealing with several LNKs lately, they seem to fail quite often.There are offerings for repair kits on Ebay including various components that fail with the switcher.Where is the transformer in your pcb?Edit: are you sure it was a LNK 364? I checked the datasheets and the 364 example circuits show flyback supplies while the 306 is a buck converter without mains isolation.That would explain the missing transformer, but maybe the circuit designer had been creative, who knows?

author: wraper
author_rank: Unknown
timestamp: December 30, 2024, 03:56:19 am
content: It's certainlynotLNK364, no transformer on PCB. Looks like it's high voltage buck converter IC. Probably LNK 304 if you can read 4 as last digit.

author: wraper
author_rank: Unknown
timestamp: December 30, 2024, 04:08:54 am
content: Found PCB photo, it's LNK304PN

author: inse
author_rank: Super Contributor
timestamp: December 30, 2024, 04:18:39 am
content: Good job!

author: AndyPen1981
author_rank: Contributor
timestamp: December 30, 2024, 07:30:33 am
content: Thats great 👍I looked at the data sheet for the LNK304 it mentions the LNK306 (which I have) on the same data sheet, could I use this instead? If not I will send for some 304s or a repair kitThanks

author: inse
author_rank: Super Contributor
timestamp: December 30, 2024, 07:58:29 am
content: Compare the specs and decide…If you can‘t, you should stay away from the repair attempt (sorry, not insulting)If you order, take at least two parts as they appear to die like flies or you missed some other broken components and fry another one

author: MathWizard
author_rank: Super Contributor
timestamp: December 30, 2024, 11:53:25 am
content: So how do these compare to Off-line switching IC's, with some internal HV MOSFET, switching a small step-dwon transformer ? So lower part count and no trans, what are some down sides though ? Fairly low current at only 120mA ?

author: Zero999
author_rank: Super Contributor
timestamp: December 30, 2024, 01:02:01 pm
content: Quote from: AndyPen1981 on December 30, 2024, 07:30:33 amAccording to the data sheet. The LNK306 is a more powerful version of the LNK304, but read the entire document to be sure. If so, then replacing the LNK304 with the LNK306 is an upgrade and will make it more reliable. Check all the capacitors and surrounding semiconductors and replace them if necessary, before replacing the IC.https://www.power.com/sites/default/files/documents/linkswitch-tn_family_datasheet.pdf

author: wraper
author_rank: Unknown
timestamp: December 30, 2024, 01:54:08 pm
content: LNK306 will work, however it has 2x current limit. Which means inductor may be too small and saturate if output overload happens.

author: AndyPen1981
author_rank: Contributor
timestamp: December 30, 2024, 08:51:26 pm
content: Upon further testing I found that the ATMEGA chip on the otherside of the board had a internal short between vcc and ground, so its a gonner.I've found a board on ebay and bought that, hopefully that will sort it.Thanks for all the help, much appreciated 👍

author: schmitt trigger
author_rank: Super Contributor
timestamp: December 30, 2024, 10:36:24 pm
content: I am glad that you have solved your problem.A relative works for an appliance repair center. Although the defective boards are not repaired and replaced with a new one, the manufacturer does require a detailed post-mortem analysis to establish the failure mechanism on selected boards.Those PowerIntegrations devices do fail on a regular basis. This is a known failure mechanism, and several engineering changes have been implemented, like beefier MOVs. However, failures continue to occur.I would love to see a FA report from PowerIntegrations, but that is proprietary information. I would not be surprised though, to see EOS listed as the failure mechanism.