Slow-to-start Holmes windows fan - Page 1
Forum section: electronics / repair

author: 13hm13
author_rank: Frequent Contributor
timestamp: May 19, 2022, 07:30:41 am
content: A very common window fan type, and has been for at least two decades. This one purch'd new in 2008, but with relatively low hours.PROBLEM: Takes a while (20 min) for fan to start working correctly. During that time, both fans just barely turn when multi-mode (electronic) button is pressed. Then (after 5 min) it will go into speeds (1, 2, 3) but only for second ... before off'ing.But then (after 15 min of being plugged in) the unit works perfectly, EXCEPT, the fans (either / both) won't spin in reverse (exhaust). When switched, to EXHAUST, they stop and hum/buzz.IMPORTANT-----BOTH FANS (MIS)BEHAVE THE SAME WAY (including non-operation on INDEPENDENT reverse switches)Took the fan apart but haven't tested anything yet (e.g., capacitance, ESR). I've heard that the starting cap (black, rectangular 2.5 uF, 250 v) can cause issues. But these are plastic (poly/ mylar???) caps, albeit cheap Chinese. There is single low-voltage electro cap on the PCB, but it does not look bulged.

author: TheMG
author_rank: Frequent Contributor
timestamp: May 19, 2022, 01:31:02 pm
content: Plastic film capacitors can degrade too. Every time they are hit with a voltage transient (surge) they can lose a bit of their capacitance, little by little with every transient the capacitor is subjected to.How does the electronic speed control work? Is it switching between different speed windings on the motors, or using some kind of TRIAC circuit? Does the control board use a capacitive dropper power supply? If so, don't forget to check that cap too as it's likely a film cap also and since it receives power at all times the unit is plugged in, would definitely be vulnerable to degradation by surges.Note: I can only see the very first picture in your post, none of the other ones work.

author: 13hm13
author_rank: Frequent Contributor
timestamp: May 19, 2022, 02:50:58 pm
content: Quote from: TheMG on May 19, 2022, 01:31:02 pmThat's eevblog's DUMB forum engine's fault. Always makes one do more work posting stuff than necessary. Sigh .... I modified .... LOOK AGAIN!

author: tunk
author_rank: Super Contributor
timestamp: May 19, 2022, 04:30:01 pm
content: Are you sure the fans themselves are ok?Just opened an ATX psu with a non-rotating fan.Oiled the bearing, now it starts slow and thenthe RPM increases after a few minutes.

author: james_s
author_rank: Super Contributor
timestamp: May 19, 2022, 05:56:56 pm
content: First thing I'd check is the motor bearings, do the fans spin freely? It's very common for the lubrication to gum up and then the motor will spin slowly until it warms up and gets loose.

author: Gyro
author_rank: Super Contributor
timestamp: May 19, 2022, 06:14:42 pm
content: Yes, I think it's going to be either the motor run (not "starting") caps self healing themselves to death - they will have been hit with the same number and size of transients, or lubrication failure.I wouldn't be at all surprised if it was a combination of both.

author: 13hm13
author_rank: Frequent Contributor
timestamp: May 19, 2022, 06:39:36 pm
content: It ain’t the bearings (technically bushings in this case) or lube. Have had mechanical issues on other, similar fans— treated several times.That’s the first thing to check — give the fan a finger nudge and watch how long that spin holds inertia.Come on folks…no dumb, obvious questions.

author: Gyro
author_rank: Super Contributor
timestamp: May 19, 2022, 06:47:56 pm
content: Quote from: 13hm13 on May 19, 2022, 06:39:36 pmErr, do you want help / ideas from people here or not?... If not, then don't ask!P.S. If you want more detailed suggestions than what are possible from the photos that you have supplied, then reverse engineer the PCB and internal wiring and post the schematic.

author: 13hm13
author_rank: Frequent Contributor
timestamp: May 19, 2022, 07:31:10 pm
content: Quote from: Gyro on May 19, 2022, 06:47:56 pmOy, guv .... 'ow you doin' taday? Yer 'ponse iz weird!! Did ya pass yer A-Levels, guv?

author: Gyro
author_rank: Super Contributor
timestamp: May 19, 2022, 07:45:33 pm
content: Quote from: 13hm13 on May 19, 2022, 07:31:10 pmLooking at your posting history, I notice that many of your recent posts are sarcastic and antagonistic, including this one [EDIT: and your "SCHWEIN HUND" avatar]. I'd be careful if I were you.Nobody here owes you answers to your questions, so do us all a favour and be a good boy.

author: 13hm13
author_rank: Frequent Contributor
timestamp: May 19, 2022, 09:38:53 pm
content: Quote from: Gyro on May 19, 2022, 07:45:33 pmOy, guv ... oh, you betcha on all yer INSIGHTFUL comments. 'Pose me photos are deep fakes .... ya know ... "sarcastic and antagonistic". ...um 'avin' a bit of a wanq, are ya, guv?ANYWAY, the problem is solved. My first hunch was right ... that it ain't the poly's. The answer is in the photo(s) and in my first paragraph.

author: james_s
author_rank: Super Contributor
timestamp: May 19, 2022, 09:49:10 pm
content: Quote from: 13hm13 on May 19, 2022, 06:39:36 pmSorry I seem to have misplaced my crystal ball so I was not aware that you had already checked these things. Are you aware that there are people of multiple skill levels on this worldwide forum that may not be as enlightened as you are? I'm not a moderator but I'll point out that people with your attitude tend to be banned sooner or later, or at the very least you will end up on the ignore list of a lot of the more experienced members for being needlessly rude, you're going on to mine now due to your attitude in this thread. If you want free help, don't be a dick to people that are trying to help you.

author: themadhippy
author_rank: Super Contributor
timestamp: May 19, 2022, 10:17:23 pm
content: Quotenot always a good idea as the oil washes out the original grease,and whilst initially things seem ok,after a while the oils gone and you've a nice dry bearing getting ready to lock up.

author: james_s
author_rank: Super Contributor
timestamp: May 19, 2022, 10:21:49 pm
content: Quote from: themadhippy on May 19, 2022, 10:17:23 pmThese things are normally sintered bronze, they'll be oil impregnated in most cases, either "permanently" lubricated or with a felt to absorb oil. I don't think I've seen one that used grease.

author: BrokenYugo
author_rank: Super Contributor
timestamp: May 19, 2022, 10:42:51 pm
content: Any one I've seen has oil wicks to keep the oilite material (which is a bronze wick) saturated with oil.

author: 13hm13
author_rank: Frequent Contributor
timestamp: May 19, 2022, 11:05:57 pm
content: Quote from: james_s on May 19, 2022, 09:49:10 pmWhoa, Nelly! Now where in EEV Forum TOS does it say anything about a paid option (I.e., not FREE)?

author: amyk
author_rank: Super Contributor
timestamp: May 20, 2022, 02:23:13 am
content: Quote from: Gyro on May 19, 2022, 07:45:33 pmThe country flag is a good indicator. It's German humour... takes a bit of getting used to.Going back to the problem, my bet is on the electrolytic - once it has warmed up sufficiently, its ESR drops enough to smooth the supply to the MCU and it doesn't keep resetting.

author: james_s
author_rank: Super Contributor
timestamp: May 20, 2022, 03:24:31 am
content: Quote from: amyk on May 20, 2022, 02:23:13 amThere are lots of other Germans on here that are not abrasive and demanding.That's a reasonable guess, can't say without testing the ESR or replacing it, although I would expect other symptoms like a dim/flickering display or obvious signs of resetting.

author: Shock
author_rank: Super Contributor
timestamp: May 20, 2022, 11:41:52 am
content: There is old adhesive on the pcb.

author: Gyro
author_rank: Super Contributor
timestamp: May 20, 2022, 12:45:42 pm
content: Quote from: amyk on May 20, 2022, 02:23:13 amEither way, I don't find him humorous. I've added him to my (very short) ignore list too.

author: 13hm13
author_rank: Frequent Contributor
timestamp: May 21, 2022, 04:13:26 am
content: Quote from: amyk on May 20, 2022, 02:23:13 amYes ... that electro cap (6.3v 1000uF). If you look at the photo, you can kinda see it swelling at top. All I had was a 50v 330uf. Which worked.BTW .... I ain't German. Just took it as a furron lang. Teacher told us never to use certain slangs.About no fun with Germany … well you’ll have to remind the BBC.https://youtu.be/eHxTiMU0aLk