Bionaire BW2100R Window Fan: diodes blown, repair still in progress

[fixitclinic]

A worldwide effort to fix a window fan: Belgium, the UK, California US and Minnesota US: 

At Virtual Fixit Clinic 557 2020-07-12 Virtual Fixit Clinic Boulder Colorado US we saw Chris from Brisbane California US:

Window Fan Bionaire BW2100R 2017 "Simply stopped working one day. (The plug fell out of the wall socket. The wall socket has since been replaced as other appliances also would not stay plugged in. Tried the fan in several other outlets, still doesn't work. ) Checked fuse it is fine. https://s7d9.scene7.com/is/content/NewellRubbermaid/DASH/S7_int/2020/BW2100R-U_43_8343646.PDF" Took fuse to hardware store. Tested out fine. Disassembled down to circuit board.  Nothing seems amiss, but I am not sure what to check for.

(Chris' initial presentation of Bionaire BW2100R Window Fan: https://youtu.be/-zNXk9UrHFg?t=2036

Intermediate troubleshooting: https://youtu.be/-zNXk9UrHFg?t=3565

Report back / summary: https://youtu.be/67ZFRaKKgKQ?t=2766)

The Global Fixers asked Chris to take photos of the circuit board and share them via Zoom's file sharing feature in the chat window. They were able to download and enlarge the photos; that helped Global Fixer Dany from Belgium notice the burned components: Diodes D1 and D2 and a totally charred Zener Diode ZD3

The suspicion is that the bad wall socket caused some sort of voltage irregularity that blew the diodes.

The next challenge: determining the values of the diode and zener diode given that the glass packaging on the zener diode was completely charred. Global Fixer Bryan from Chailey UK offered to research a schematic but instead replied:

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On Tuesday, July 14, 2020, 1:39:40 AM PDT, Bryan wrote: (edited)

Sorted!!!
One of our electrical  volunteers found a very similar circuit board used by the same company:

 

Looking carefully, we can see that the zener diodes are 12 volt 1 watt - you can buy them here:
1N4742A 12V 1W Generic Zener Diode 5 pcs | eBay
(This is for 5) pcs of the 1N4742A Zener Diode. 
And the non-zener diodes (I’d replace both of them) next to it on your board are IN4007 diodes 
https://www.ebay.com/itm/100pcs-1N4007-IN4007-1A-1000V-Rectifier-Diode-DO-41-4007/223002718489?hash=item33ebff7119:g:lLYAAOSwkkNbEyX0
(You usually have to buy them by the 100, but they are very very cheap!)
Now - all you need to do is to find somebody to fit them for you - I’m free some of this week and it’s actually quite sunny here in South East England…….!!!

 

A couple more comments from the team here:
"I don’t like the look of D2 - has the end blown off?"
"I’d scrape the glue off around the electrolytics as it can go conductive - especially if it has carbonised, which some of it has."
That last comment about the white glue which has been used getting carbon particles in it  and then starting to conduct electricity…..
(Peter - would you like to copy this to Dany in Belgium and ?Howard, who were in the breakout room with us?)
Hope that helps,
All the best,
Bryan

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Global Fixer Howard from Minneapolis chimed in:

From: Howard
Subject: Re: Chris' Bionaire BW2100R Fan
Date: July 14, 2020 at 12:02:47 PM PDT
...
Found 1 watt 12 Volt 1N4742A shipped to the US by US Shipper (Ohio)... $2.15 for 10:
https://www.ebay.com/itm/1W-Zener-Diode-3V-47V-DO-41-DO41-10-Pieces-1-Watt-USA-SELLER/223918976621?hash=item34229c6e6d:g:uwIAAOSwpBdeTLH~#shpCntId
Found 1n4007 shipped to US by US Seller (California) $1.78 for 10: https://www.ebay.com/itm/10pcs-1N4007-Rectifier-Diode-1A-1000V-US-Seller-Free-Shipping/132438969443?epid=2255930237&hash=item1ed5fa4c63:g:fMAAAOSwB-1YuRh3

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And now the conversation has shifted to the kind of soldering equipment Chris should obtain to replace these components.

Great work everybody: it’s wonderful to see this kind of inter-continental collaboration!

[Angel Uruena]

Congratulations!