Replace eixsting antiparasitic filter with a new one but with different specs - Page 1
Forum section: electronics / projects

author: sdancer75
author_rank: Frequent Contributor
timestamp: September 10, 2024, 07:02:58 am
content: This part is taken from a washing machine Candy model go 108 s16 that is connected to a PCBhttp://skyprog.net/en/manual/lib/candy_con_2.jpgThe original filter specs are 1μF and two 27000pF connected directly to the PCB with a SMPS IC Viper12A. It's hard to find a replacement one. Can I replace the original with another filter but with different specs, i.e., 0.47μF and two 4700pF? Will this affect the microcontroller functionality which is very sensitive to noise?The problem with this washing machine is the program selection. Despite the user's selection, it is taking a random program. I checked the board and it seems to be ok.The anti-parasitic filter after 14 years of working is out of its nominal specs, so it needs to be replaced anyway.Please check the attachments of the described filters.

author: moffy
author_rank: Super Contributor
timestamp: September 10, 2024, 07:36:59 am
content: Have you tried the new filter to see if it works, and solves the noise issue? It should be safe to do so as the voltage and current specs look to be higher. Trying it out will be the most definitive way to get your answer.

author: sdancer75
author_rank: Frequent Contributor
timestamp: September 10, 2024, 09:49:57 am
content: Quote from: moffy on September 10, 2024, 07:36:59 amHi, yes the current & voltage are higher but the capacitive is lower. That actually concerns me most, rather than the voltage/current.

author: moffy
author_rank: Super Contributor
timestamp: September 10, 2024, 10:11:23 am
content: Try it and see.

author: wraper
author_rank: Unknown
timestamp: September 10, 2024, 10:20:12 am
content: There is zero chance this filter has anything to do with the issue and zero chance better filter will help. You need to fix the controller, I'd start from checking if button switches did not become somewhat conductive in open state. Or program selector encoder might be bad. How did you determine that original filter is out of spec? Did X capacitor lose capacitance or what?

author: sdancer75
author_rank: Frequent Contributor
timestamp: September 10, 2024, 12:26:54 pm
content: Quote from: wraper on September 10, 2024, 10:20:12 am>> X capacitor lose capacitance or what"Yes, that's correct ">> There is zero chance this filter has anything to do with the issue and zero chance better filter will help.I had a similar conversation with a forum member (not here) about the same topic approximately 4-5 years ago.I remember another instance in the past when I had a similar issue with a dishwasher. The symptoms were errors in the middle of the program, or even worse, the selected program would run for hours without completion. I had a hard time finding the root of the problem on the PCB. All the parts seemed fine, except for the XY polypropylene film capacitors. Once I replaced them, the machine worked perfectly and is still running smoothly today.I suspect EMI/RFI interferences can cause problems in microcontrollers that are very hard to spot in some circumstances, especially when the PCB design is poor.>> I'd start from checking if button switches did not become somewhat conductive in open state. Or program selector encoder might be badYes, I was thinking of that too. I will try 1st this capacitor and then I will check/replace the program selector encoder. I didn't check this part and I am not sure how to do it. It is cheap ~10 euro so I might replace it in the end.

author: sdancer75
author_rank: Frequent Contributor
timestamp: September 10, 2024, 12:27:34 pm
content: Quote from: moffy on September 10, 2024, 10:11:23 amYes, I am thinking of it :-)

author: sdancer75
author_rank: Frequent Contributor
timestamp: September 15, 2024, 07:43:05 am
content: UPDATE: The antiparasitic filter is replaced with a new one using the same specs. I cleaned also the selection encoder with a contact spray.The washer it works now as it should be.So problem is solved. Thanks to all.