Author Topic: total novice needs advice on zener diodes  (Read 723 times)

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Offline emmajackt

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total novice needs advice on zener diodes
« on: December 02, 2018, 11:54:54 pm »
Hi, I am a total novice when it comes to circuit boards and was wondering if someone could help me. I have a Horizon Omega CS treadmill and there was a loud bang when I plugged it in last week and the circuit board had blown a couple of transistors and a couple of zener diodes. As the diodes have blown, I am unable to test what voltage ones I would need to replace them. I am attaching a picture of the same diode that i need and would be really grateful if someone could help me. I have looked online for a diagram of the circuit board with no luck

Thank you, Kev.
« Last Edit: December 02, 2018, 11:56:54 pm by emmajackt »
 

Offline FriedMule

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Re: total novice needs advice on zener diodes
« Reply #1 on: December 03, 2018, 07:47:45 am »
I am a novice like you so my advice can be the worst thing to do but I would try to locate if there are some place where it says the voltage and then work backward and if that do not work I'll put ZD in with a wary low voltage and then put one with a higher voltage until it looks to work fine.
 

Offline capt bullshot

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Re: total novice needs advice on zener diodes
« Reply #2 on: December 03, 2018, 08:00:56 am »
If you just want to replace the diodes and transistors, you'll have to get some documentation or information from the manufacturer or a very similar unit. I don't have either of these.

Otherwise, one would try to reverse parts of the schematic to get an idea of what is the purpose of these diodes, why they were blown and make an educated guess on their value.
Safety devices hinder evolution
 

Offline mvs

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Re: total novice needs advice on zener diodes
« Reply #3 on: December 03, 2018, 09:49:15 am »
the circuit board had blown a couple of transistors and a couple of zener diodes
ZD1 is a Zener diode designator, but D12 is not. If it was also in glass DO-35 package, it might be 1N4148.
If you make good photos of the board from both sides, perhaps we can derive components from their functions.
 

Offline emmajackt

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Re: total novice needs advice on zener diodes
« Reply #4 on: December 03, 2018, 08:16:46 pm »
Hi, thank you for your replies. I have attached a few more pictures of the whole board and a picture of the diodes that I need, from a picture I found online. The treadmill is quite old and not worth spending ££s on it. I really appreciate your answers. I thought it would be a case of replacing the two blown diodes, one blown resistor and the two transistors and hoping for the best, but obviously there's more involved and I cannot find a schematics for the treadmill anywhere.

Regards, Kev
 

Offline Johnny10

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Re: total novice needs advice on zener diodes
« Reply #5 on: December 03, 2018, 09:20:17 pm »
It looks to me as though you might be able to buy boards and replace.

 The Omega II manual has pics of PC board but no schematic.

http://productload.johnsonfit.com/inc/uploaded_media/ba2e870dabd6373a48f8e138dfc9c56f/service_guide/54c14b21a33d970fb0beb252b7d83034.pdf


I don't know your exact Model number but look here.

https://www.ereplacementparts.com/horizon-fitness-treadmill-parts-c-201405_201552.html


Oh, But they are over $250 for Motor Controller Boards... OUCH !

Sorry, Guess I wasn't much help.
 Or these guys charge about $75 to do repair.
I saw them on eBay.


« Last Edit: December 03, 2018, 09:55:19 pm by Johnny10 »
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Offline emmajackt

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Re: total novice needs advice on zener diodes
« Reply #6 on: December 03, 2018, 09:53:45 pm »
Wow!! I think the treadmill is only worth £30. Thanks so much for finding this though. Much appreciated.

Regards, Kev.
 

Offline Brumby

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Re: total novice needs advice on zener diodes
« Reply #7 on: December 04, 2018, 12:49:32 am »
A word of warning ... even if you do correctly identify the failed parts and replace them, the questions still stands: Why did they fail?

If the fault condition was in one of those components that were replaced, then you have a fair chance that the replacements will fix the problem - but if it was not, then the replacement components might also meet an inglorious death.

... and you will be back where you are right now.
 

Offline capt bullshot

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Re: total novice needs advice on zener diodes
« Reply #8 on: December 04, 2018, 06:33:52 am »
Looks like this board does some serious mains voltage control. Having small components going bang on such kind of board usually has its root cause somewhere else, not the components itself.
Safety devices hinder evolution
 

Offline emmajackt

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Re: total novice needs advice on zener diodes
« Reply #9 on: December 04, 2018, 11:54:12 am »
Thank you for all of your advice. I think this repair is beyond my very limited electronics knowledge, so instead of wasting money, I think I will scrap it and look on Ebay for another.

Thanks again for all your replies and have a great Christmas.

Regards, Kev.
 


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