Ventline model 5079 monitor board

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tony92630

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Lake Forest
Hi all, I am new to this forum. I have a request-- Does anyone on here have information on where to get this monitor board and or the wiring diagram as well. Please reference the attachment below. It looks like the circled component is burned out. I am getting no reading when I use my meter. Better yet, if anyone can tell me the value or where to get this component, that would be great! Also, if any one has a tech manual to send me?? Much appreciated!!

Warm regards,
Tony
 

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DonTom

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Auburn, CA or Reno, NV or Cold Springs Valley, NV
Hi all, I am new to this forum. I have a request-- Does anyone on here have information on where to get this monitor board and or the wiring diagram as well. Please reference the attachment below. It looks like the circled component is burned out. I am getting no reading when I use my meter. Better yet, if anyone can tell me the value or where to get this component, that would be great! Also, if any one has a tech manual to send me?? Much appreciated!!

Warm regards,
Tony
It looks like it could be a small electrolytic capacitor. Get an ANALOG ohmmeter, but it on a high ohms range and see if you get a "kick" on the meter that slowly decreases. Then reverse the leads and get a faster kick. But that also means it is probably good.

-Don- Auburn, CA
 

tony92630

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Joined
Mar 6, 2021
Posts
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Location
Lake Forest
Hi Don, I have already performed that test and did not get any "Jolt."
do you have any ideas where to purchase a board ? Or, a substitute board that is a plug and play so to speak?
Thank you,
Tony
 

tony92630

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Lake Forest
removed part # is In4734A and is a diode Will order part and let know how it turns out . Thank for moral support. & directions but some time you cant see the forest because of the trees. Thanks Don
 

DonTom

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removed part # is In4734A and is a diode Will order part and let know how it turns out . Thank for moral support. & directions but some time you cant see the forest because of the trees. Thanks Don
An IN4734A is a 5.6 volt Zener Diode! It is used as a voltage regulator to get that 5.6 DC volts. How did you test it?

It works by reverse bias. IOW, when there is above 5.6 VDC applied to it in reverse bias, it lowers the resistance to draw enough current to get down to 5.6 VDC.

However, they normally do draw current in forward bias direction. I would use an analog voltmeter on a high ohms scale and check in both directions. But that is not really a good test for a Zener Diode.

See here for other methods.

BTW, if that diode is open (rare) the voltage will be too high.

If it is shorted, the voltage will be too low.

The very best way to test it is in circuit, live and measuring 5.6 VDC (or very close to it) across it.

Let me look up the spec sheet.

So the lowest voltage should be 5.32 volts. The highest should be 5.88 volts. The norm will be closer to 5.60 VDC in normal operation.

-Don- Auburn, CA
 

tony92630

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Tested with analog meter open circuit both way. will reinstall venthood tomorrow. At least this is keeping me out of trouble I think. thanks Don
 

DonTom

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Tested with analog meter open circuit both way. will reinstall venthood tomorrow. At least this is keeping me out of trouble I think. thanks Don
What ohmmeter are you using and on which ohms scale?

You need to have enough voltage across the diode to turn it on.

Many people incorrectly believe a diode only lets juice go one way. This is kinda true, but the way they really work is more like a switch. A normal silicon diode requires above 0.6 volts on the anode (compared to the cathode <the line on the diode>)for it to start conducting. When it is reversed you have negative voltage at the anode, so the diode turns off and no longer conducts.

But a Zener diode is designed for REVERSE bias, the opposite of above. That is what makes them good voltage regulators. They "breakdown" at a certain voltage and can be designed for various breakdown voltages. But your ohmmeter has to have above the Zener voltage to see the reverse bias effect.

However, they USUALLY can be cold tested in the forward bias direction and get that 0.7 VDC drop. Then your ohmmeter has to supply more than than 0.7 (in most cases) to turn on.

The problem is there are exceptions. Take HV didoes for an example. Those are usually many didoes in series in a single package. Let's say there are ten diodes. So instead of needing 0.7 volts, you now need a full seven volts for that diode package to show any indication at all on an ohmmeter.

But I do not know how your Zener diode will read on an ohmmeter. But higher ohms scales are higher voltages on analog meters, so you could get a reading.

But think about this. Let's say that diode is really open. That means you still will have a problem after the diode is replaced (most likely). Because that diode, when good, can only drop a voltage. It does nothing else. So when it opens, the voltage goes too high. So what does the too high of voltage do after that? One thing it won't do is stop whatever it is from working unless something is damaged from when the diode opened.

So do NOT expect replacing that diode to fix anything. It is very unlikely (but not impossible).

The only good way to test it is live and check for the ~5.3 volts. The +5.3 volts should be on the cathode, negative lead of voltmeter on the anode. If you have 5.3 volts there, it means your problem is NOT there.

And TBH, I don't think that is your problem. I would be looking elsewhere.

Now if that diode was shorted, I would say you found the problem as then the voltage there would be way too low to run anything.

Anyway, if you mean you're going to put it back and check the voltage, that is the very best way to check. Be sure to post here what you get. My guess is you will find your 5.3 volts there, if you have voltage going into the card to begin with.

If you have no voltage there and the diode is really open, your problem is NOT the diode, but something before it.

-Don- Auburn, CA
 
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tony92630

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Tested diode using 9 volt battery test reading was 4.75 so that means its good . I will reinstall venthood see if any has changed . I found a shorted fuse in the venthood it self that I didn't know about . will keep you informed tony
 

DonTom

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Tested diode using 9 volt battery test reading was 4.75 so that means its good . I will reinstall venthood see if any has changed . I found a shorted fuse in the venthood it self that I didn't know about . will keep you informed tony
I hope you had a resistor in series with that 9V battery. But perhaps the low current capacity of a 9V battery will not harm the diode anyway. But 4.75 volts is a bit low, the min voltage should be 5.32V. Nevertheless, I doubt the Zener diode is your problem.

Shorted fuse? I assume you mean open fuse. That has good odds of being your problem, but it could be a sign of another problem. But also, perhaps not. Fuses can go bad simply from age and vibration. Like any other electronic component, a fuse can fail. More common when the values are small, because then the fuse element is thin.

Good luck.

-Don- Auburn, CA
 

tony92630

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Well Don replacing the fuse cure most of my problem . I now have a feed back issue as the lights stay on dim . but when you press test button they are normal brightness.
 

DonTom

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Well Don replacing the fuse cure most of my problem . I now have a feed back issue as the lights stay on dim . but when you press test button they are normal brightness.
Unfortunately, I don't even know what a "Ventline model 5079 monitor board" is or what it monitors. At this point, I doubt it I can be much help unless there is a schematic of the entire system.

But it sounds like the test button is providing more voltage to the lights by bypassing a circuit or something like that.

Do you have any info at all, so I can get a rough idea of at least what it is that you're trying to fix?

But now would be a good time to see if the voltage across that Zener diode if below or above 5.32 volts. If less than 5.32, that could be your problem, but still unlikely to be caused by the Zener diode but something before it not giving the Zener diode enough voltage / current to get up to its breakdown voltage. Also, when you press that test button see if the Zener goes to above 5.32 volts.

-Don- Auburn, CA
 
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tony92630

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Lake Forest
sorry should have stated it monitors the holding tanks /LPG /battery / fresh water. Don you helped so very much I can.t thank enough Tony
 
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