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Old 10-06-2013, 05:26 PM   #16
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Circuit Board on Tankless Water Heater Issue?


Yes i see the x1k now. i didnt see that the first time
The rings must be severely discolored. A 6.8K resistor would be Blue,Grey,Red and all those rings look black and brown lol

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Old 10-06-2013, 05:31 PM   #17
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Circuit Board on Tankless Water Heater Issue?


Is there any way you can get to look at a new board ?
And read the color bands off the resistor ?
It's important that you get the right value !
Once you know for sure, you will save a heap of money.
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Old 10-06-2013, 05:32 PM   #18
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Circuit Board on Tankless Water Heater Issue?


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Yes your reading the scale wrongly !

In the first post there is a picture of the meter and it's setting,
It is on x 1K ohm, so the reading on the meter is around 7,
so this becomes 7K ohms.

The closest standard value to this is 6.8 K ohm.
The heating would easily cause the value to rise from 6.8 to 7.2.
Using a larger wattage rating won't hurt.
But I would not use a wirewound resistor in place of resistor,
that was not wirewound.
As this can introduce an inductive component to the circuit.
Use only what the manufacturer has used.
Which is a fusible type.
They do make 3w fusible
You could use 2 x 3.9k ohms is series
This would give 4w or 6w depending on the resistors you use 2w or 3w.
This resistor appears to be used for voltage dropping purposes (it may even be in series with that LED to act as an indicator operating at line voltage - the current works out about right), so I would not use a lower value than what is measured. It looks to be a bit over 7k, and most of these resistors are +/-5% tolerance. 7.2k or 8k should be fine. The circuit has no high frequency stuff going on which could cause a problem with a wirewound resistor and they are more commonly available in high wattage ratings. This is not complicated or particularly critical.
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Last edited by mpoulton; 10-06-2013 at 05:35 PM.
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Old 10-06-2013, 06:39 PM   #19
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Circuit Board on Tankless Water Heater Issue?


Lots to report since last post, so this may be a little long:

I wired back in the "good" board that was giving us luke warm that I took out to test Friday night, but it no longer works. I labeled the wires, so I'm fairly certain I wired it right. The light does not come on anymore and the water stays cold. I took it back out, and the resistor was still reading the same 7.1 or 7.2 though. So, I have only cold water now; and now there is more urgency with a wife and four daughters under age 7.

Saturday morning, I went to Radio Shack hoping they might have a resistor as the closest electronic parts stores are about 30 miles away and probably not open on Saturday. I told him what resistor I thought I was looking for and brought in the 3 boards and the meter I was using. They had a limited selection with no 2 or 3 watt resistors at all. I asked if he had a digital meter, and he tested the resistor which read 11.92K on his meter. He asked if I calibrated the meter, and I remembered an earlier post from this thread mentioning that. He quickly calibrated (turned the dial on the side of the meter getting the starting point right to zero) and showed me. Now the analog read right under 12 when set to the 1K setting as well. So, he suggested looking online for a 2 or 3 watt 12,000ohm resistor or going Monday to a couple electronic stores about 30 miles away.

Just down the road from Radio Shack is a TV repair guy who a friend suggested visiting as he repairs TV circuit boards and may be able to help. I showed him the 3 boards and told him everything I knew up to that point. He said the 2 bad board's resistors were "open" which he said basically meant bad. He also read right under 12,000 ohms on the other resistor, and asked if it still worked because he thought the resistor physically looked as bad as the others and that the resistor was likely not a 12,000 ohm resistor but was giving a 12K as it was degraded and close to completely failing/being "open". He did not think a 12K ohm resistor made sense in that board setup.
He said we really needed a good board to test the resistor, but that then we could look at the color bands just as well. He also suggested calling the water heater company to see if they would tell me what resistor is used or pay the $70 to get 1 new board in and then we could likely fix the other 3 boards because we had a good board to start with. He mentioned that when the resistor went bad other parts could have been damaged as well, and his largest concern with fixing the 3 bad boards was if it damaged the chip which he said could be proprietary.
So Monday is tomorrow, and I will call EEMAX in the morning to see if they will tell me what resistor is used or at least look at a board and tell me what colors are on it if they happen to not know. Hopefully, that will be the only issue with the board. I will update tomorrow after I call.

Last edited by jason586; 10-06-2013 at 06:44 PM.
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Old 10-06-2013, 10:22 PM   #20
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Circuit Board on Tankless Water Heater Issue?


That guy knows what he's doing. If he will work with you on fixing these boards, you'll be all set.
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Old 10-07-2013, 11:12 AM   #21
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Circuit Board on Tankless Water Heater Issue?


I called EEMAX this morning. They use a different board now, so he had to look for an old board for the colors. He found one and said the color bands were Brown Black Orange Gold, and said there was a note he found that said it was a "10K resistor with 5% tolerence". I haven't looked it up yet to confirm those colors are 10K as I am on my way out the door.
I guess I should look for a 3 watt (not 2 watt) 10K flameproof or metal oxide resistor.
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Old 10-07-2013, 11:34 AM   #22
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Circuit Board on Tankless Water Heater Issue?


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I called EEMAX this morning. They use a different board now, so he had to look for an old board for the colors. He found one and said the color bands were Brown Black Orange Gold, and said there was a note he found that said it was a "10K resistor with 5% tolerence". I haven't looked it up yet to confirm those colors are 10K as I am on my way out the door.
I guess I should look for a 3 watt (not 2 watt) 10K flameproof or metal oxide resistor.
Yep, those colors are a 10K resistor with 5% tolerance.
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Old 10-07-2013, 12:18 PM   #23
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Circuit Board on Tankless Water Heater Issue?


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I guess I should look for a 3 watt (not 2 watt) 10K flameproof or metal oxide resistor.
5W, not 3W. 3 versus 2 is not much difference and you're likely to have the same problem again. And it really DOES NOT MATTER what kind of resistor you use, as long as it meets the electrical specs. In this power and resistance range, the vast majority of available products are wirewound, not film. Here's a non-inductive wirewound resistor what will work fine:

http://www.digikey.com/product-detai...TCT-ND/3114518
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Old 10-07-2013, 02:49 PM   #24
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Circuit Board on Tankless Water Heater Issue?


Are there issues with going too high of wattage that could risk damaging other parts of the board? I was thinking 3 watt was the smallest increase available but was still a 50% increase and probably a low risk of damaging other parts of the board.....I really have no idea though.
No potential issues with going to a 5 watt?

Quote:
Originally Posted by mpoulton View Post
5W, not 3W. 3 versus 2 is not much difference and you're likely to have the same problem again. And it really DOES NOT MATTER what kind of resistor you use, as long as it meets the electrical specs. In this power and resistance range, the vast majority of available products are wirewound, not film. Here's a non-inductive wirewound resistor what will work fine:

http://www.digikey.com/product-detai...TCT-ND/3114518
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Old 10-07-2013, 03:39 PM   #25
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Circuit Board on Tankless Water Heater Issue?


Quote:
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Are there issues with going too high of wattage that could risk damaging other parts of the board? I was thinking 3 watt was the smallest increase available but was still a 50% increase and probably a low risk of damaging other parts of the board.....I really have no idea though.
No potential issues with going to a 5 watt?
No. The wattage rating is the maximum power dissipation the resistor is designed to handle under optimal conditions. The actual power it dissipates is dictated by the operating conditions of the circuit (V^2/R), not the rating of the resistor. This is not like the wattage rating of a lightbulb or heater.
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Old 10-29-2013, 09:09 AM   #26
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Circuit Board on Tankless Water Heater Issue?


I was cleaning out my email and saw a DIY email, and realized I forgot to post what happened.

I ended up buying a 10 pack of 3 watt 10K resistors on ebay for $6.10 shipped, and we soldered them onto the 3 boards. I wired up the first board and nothing. I wired up the second board and nothing. I tried switching the boards around and nothing.
So, I called EEMAX in case I wired them wrong even though I was fairly sure I had not. The EEMAX guy confirmed I had them wired right, and then asked if I had screwed the boards back into the gray tube were the heating element sits inside. I said I had not done that yet, and he said the it will not work unless they are screwed in as there is a sensor that can feel the water running that tells it to turn on. So I screwed down the first one and sure enough warm water. Then screwed in the second board and HOT WATER!

So for all the people that HATE this water heater and post 1 star reviews about it online due to having to continue to buy new $70 boards, hopefully they will find this thread through a google search as it is only a 60 CENT RESISTOR that will likely fix their boards.

Last edited by jason586; 10-29-2013 at 09:11 AM.
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Old 10-29-2013, 09:23 AM   #27
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Circuit Board on Tankless Water Heater Issue?


I'd be more concerned about why the resistors went bad.
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Old 10-29-2013, 05:55 PM   #28
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Circuit Board on Tankless Water Heater Issue?


Probably running too many watts !
Running close to it's limits !
Then put it in a box with little or no ventilation !
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Old 10-29-2013, 06:35 PM   #29
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Circuit Board on Tankless Water Heater Issue?


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I'd be more concerned about why the resistors went bad.
That is my thinking as well. All to often, when replacing an obvious bad component, there is in reality another component that went bad that caused the actual problem. I'm pretty sure your going to have a repeat problem soon.
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Old 10-29-2013, 07:58 PM   #30
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Circuit Board on Tankless Water Heater Issue?


Yeah, I'm not so sure about the longevity of this repair. A 3W resistor is barely larger than a 2W, and it takes a LOT of excess heat dissipation to make one fail. That's why I recommended 5W replacements. It's like replacing a broken 1000lb chain with a 1500lb chain, when you could just as easily step up to a 2500lb rating. This is a pretty temporary fix, I think.

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