Can this ceiling fan remote be fixed?

[Los_]

Hi all,
are there any steps you usually take to troubleshoot this type of remote? 35T1
The control has been working sporadically, sometimes it takes a few tries to turn on the fan or light but recently it stopped working for good. The LED still lights up when I press any of the buttons so it seems like the remote still has some functionality but somehow is not communicating with the receiver. That is how I picture this issue in my head, I'm wondering if there is a way to know what part has burned out or needs replacing.





Note: I should be getting a new remote soon to confirm that it is a remote issue vs receiver but I would like to understand how this remote works, it'd be nice to know which parts tend to go bad or repair tips in general.

Thanks in advance for your time!
-Los

 

[kellys_eye]

Look at the Infra-red LED (the clear one on the end of the remote sender) through a mobile phone camera and see if it 'glows' - if it does then the transmitter is probably ok. The most likely issue is at the fan - is the receiving sensor clear of dirt etc.

Does the fan respond at all to the remote? If the LED glows when you press any button (check them all) then the buttons themselves are ok else change out the ones that DON'T make the LED work.

 

[Bluejets]

These things are never made to be repaired.
They cost cents to produce, are often multi layered and use lead free solder which is a right pain to modify.
Chuck it and buy a new one, that was the manufacturers original design consideration for certain.

 

[Los_]

Look at the Infra-red LED (the clear one on the end of the remote sender) through a mobile phone camera and see if it 'glows' - if it does then the transmitter is probably ok. The most likely issue is at the fan - is the receiving sensor clear of dirt etc.

Does the fan respond at all to the remote? If the LED glows when you press any button (check them all) then the buttons themselves are ok else change out the ones that DON'T make the LED work.

Thanks for your quick reply!
Yes, the LED glows when I press any of the buttons but none of them are working anymore. That caught my attention and I was just curious to see what other components may be failing. I saw that "saw" component and I thought it was interesting to see that. is that what is being used to emit different signals? I understand if this can not be fixed I was more interested in the concepts and lessons to be learned from this small circuit

 

[kellys_eye]

That 'SAW' device is a Surface Acoustic Wave device (a filter) that sets the operating frequency - usually in the 433MHz band (could be different of course) - but the LED 'glow' is actually the LED pulsing on/off very fast sending the appropriate code to the receiver. The possible faults are the key fob isn't sending the code or the receiver isn't working.

Clearly, the only way you can determine this is to use another key fob (neighbours?) to discover whether the fob or the fan is the issue.

As I already said though, the LED signal needs a clear path to the receiver and dirt on that receiver can stop it working.

 

[Los_]

Thanks for your insight! Makes sense!

 

[kellys_eye]

These things are never made to be repaired.

Whilst true, the usual cause for failure is the push buttons themselves and if they work (as per the OP saying the LED glows when the buttons are operated) the odds on the rest of the electronics failing is fairly remote. All said, my latest reply above should sort it out once and for all.

 

[bertus]

Hello,

It looks like the fob uses RF. There is a curly trace near C13 and C14. That would be that antenna.
The led only seems to be an optical indicator.

Bertus

 

[dave9]

^ BINGO! This is an RF remote, not IR. Besides, an IR LED can't cycle anywhere near as high as ~300MHz where these operate and was stated plus the orientation of the LED, that it's just a visual indicator that a button was pressed.

Stupid question but, did you check the battery voltage? Is the receiver mains powered or battery and maybe it's got the low battery?

Check all solder joints for cracks?

 

[kellys_eye]

It looks like the fob uses RF. There is a curly trace near C13 and C14.

Good spot! Missed that!

The SAW device will set the transmit frequency which must also match an equivalent device in the receiver. I can almost see some markings on the top of the SAW device - can you tell us what it actually reads?

 

[dave9]

^ It reads:
H
P303A
(or maybe R303A)

See this page, states 303.9MHz and you can see how this is situated in the casing:

https://www.amazon.com/Ceiling-Replacement-L3HFAN35T1-FAN-35T1-L3HFAN35T/dp/B0922K9NJD

The FCC pic has one that's 303.875:

https://fccid.io/L3HFAN35T1/Internal-Photos/Internal-Photo-1307608.pdf

https://fccid.io/L3HFAN35T1

Schematic: https://fccid.io/L3HFAN35T1/Schematics/schematic-1307604.pdf

 

[bigkim100]

More than likely is excessive use of the push buttons. Try bypassing them with a piece of wire, and see if that function works.

 

[Los_]

Wow, this is really detective work right here! just as expected from pros like you guys
Thanks for looking into this!
The SAW reads "H" on top then "R303A" as mentioned by Dave9
I have a brand-new battery. I will try soldering any loose connections to see if that helps.
Would you say that the DIP switch in this case works as an amplifier? meaning, that it has the ability to change the frequency on the SAW device?
is there a device that can capture the frequency signal and read it back?

Thanks again for sharing knowledge
-Los

 

[dave9]

^ I think it's more likely something like a pairing code that the DIP switches set, and no the dip switches can't change the saw threshold which is just shunting to ground, but I wouldn't put too much work into this when (if you're in the US or another market with amazon or ebay available) they are available in the aftermarket brand(s) for a very reasonable ~$17 USD price.

 

[Los_]

Thank you, dave9
I got the replacement last night and it works 100%.
I was more curious about the troubleshooting steps and I feel like this was a good learning experience
Thank you all for the great feedback!

-Los