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Wi Lite wireless lighting switch

bushtech

Sep 13, 2016
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Sheesh St Edd! When do you you sleep?

Will start checking very carefully. Hate working on boards with mains power connected to them
 

bushtech

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St. Edd
Please sit in a chair with armrests when you see this. Would hate you to hurt yourself falling off your chair when you see these bodges. I had to move two diodes offboard due to space constraints and board damage to solder pads from my earlier attempts when I was still learning how to unsolder successfully

This is a photo of the damaged board as it now looks

20161009_141342.jpg

Cap Readings from the 2 boards

Undamaged board
Blue 18.2V
Orange 2.9V
Chartreuse 9V

Damaged board
Blue 11.1V
Orange 0.1V
Chartreuse 1.4V

Both tests were done without test lamp attached

Thanks a mil again for all the help
 
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73's de Edd

Aug 21, 2015
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Will have to comment on the above pic later.
With the info on the board readings below:
Cap Readings from the 2 boards

Undamaged board
Blue 18.2V . . . . . . . . . . . Main supply level
Orange 2.9V . . . . . . . . .This must be the supply level for the daughterboard
Chartreuse 9V . . . . . . . .A normal intermediate voltage supply level.

Damaged board
Blue 11.1V . . . . . . . . . . .We can see that it is producing power, but loaded down.
Orange 0.1V . . . . . . . . . .Looks like this supply is shorted to ground
Chartreuse 1.4V . . . . . . . Looks like the Orange supply is pulling down this
supply to only being able to create this lower voltage.

Power down the board and pull out the ohmmeter and just see if we don't have a
shorted Zener diode connected to the Orange capacitor line.
I can't see all components being located down between the daughterboard and the Orange-
Chartreuse E- caps and Tact switch.


73's de Edd
 
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bushtech

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Thanks St. Edd
Here's a photo of the area you can't see. I removed cap C4 which was blocking view.

20161010_105516.jpg

As can be seen I replaced I replaced D2 with a 1n4007. Could that have been a zener as I was getting reading both ways when testing for a diode. It was also an orange job like D5. I can't see any Zeners attached to the orange cap line but then I'm probably not much good at ID'ing Zener diodes. Will now start swotting up Zener diodes
 

bushtech

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Could it be that I have replaced Zener diode at D2 with a normal diode?
 

bushtech

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I retested the removed diode D2 as it's now off board.

Using analogue MM:

In X1 range:
30 ohm & 0M
So it tests good as a diode

In 10k range
I get a reading both ways

So if it's a Zener it's bad

How do I determine if it's a Zener or a diode
 

73's de Edd

Aug 21, 2015
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Sir bushtech . . . . . . .

On that MELF profile diode that you pulled , do a Vf "diode" test on it, vice the ohms test that was resulting in its giving a 30 ohms forward reading.
Then see if its reading in the 0.500---0.700 VDC range, as would be expected on a good silicon diode junction...
THEN to see it it has a Zener action, series clip two 9VDC batteries M & F connectors together for a resultant 18VDC , a series 1500 through 2200 ohm current limiting resistor clip leads to the + battery connector.
Then the tested diode has its cathode/band going to the free end of that resistor while its anode lead goes to the battery negative connector.
Then you DC meter across the tested diode, with your third and fourth hands, and expect ~9 or ~ 3VDC if they are using a Z diode for the acquisition of the sub power supplies.
If it reads on up in the 18VDC range , then you have no zener action in the range we would expect to find being used. . . . . assuming it to then be a common silicon diode.

So THEN you go back to your good working unit and measure across that equivalent diode on its board and get its DC voltage reading across it.


73's de Edd
 
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bushtech

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Thanks St Edd

I am still a novice when it comes to electronics, lots to learn. Don't know what you mean with a Vf "diode" test. Took DMM on diode function and it reads 692 one way, nothing other way.

For your Zener test I'm busy rounding up the bits and bobs required.

But it looks like third and fourth hands are unobtainium:)
 

73's de Edd

Aug 21, 2015
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" Took DMM on diode function and it reads 692 one way, nothing other way. "

Why certainly you do, that is the voltage level across a conducting semiconductor junction.
You just successfully found 692 millivolts being across that unit.
 

bushtech

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Lol. Blind luck. I sometimes feel like a blind man trying to solve a Rubik's cube.

So far found an adjustable wall wart that pushes 19V on it's 12 V setting. Now for that resistor
 

bushtech

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On the pulled diode I get 9.2V. This is with pushing 19.7V through the circuit and a built up (3 resistors) series resistance of 1627ohm.

Just as an aside when I measure the resistance of each resistor and add them up it equals 1627 ohm. But when I meter across all 3 resistors using the lowest ohm setting on my meter I get 1181ohm. Huh?

And when I measure the voltage of the equivalent diode on the good board I get 9.1V.

So it looks like I've got to put that pulled diode back and see what we get.
 

bushtech

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I put that zener diode back but still get 11.24V, 0.1V and 1.46V. Still think the diode is fubar. I am going to be ordering some zener diodes as I don't have any spares. What should I be looking for specwise?
 

bushtech

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Is that 9.1 V I found the reverse voltage of the zener? What is the 692mV I found? Busy swotting up zener diodes so I can try and spec the replacement.
 

bushtech

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OK, so it looks as if the 692mV is the forward voltage of the diode
 

bushtech

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St Edd

You said:
Damaged board
Blue 11.1V . . . . . . . . . . .We can see that it is producing power, but loaded down.
Orange 0.1V . . . . . . . . . .Looks like this supply is shorted to ground

How do I troubleshoot Blue 11.1V as this seems to be the first problem?
 

bushtech

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St Edd
You were right and I was wrong at looking up the data sheet for the relay. I should just have looked at the relay where it states DC24V
 

bushtech

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I have started created the circuit in LTspice. My first foray into LTspice so huge learning curve and I hardly know what I'm doing. It's not finished but I'm trying to create the first part up to the Zeners.
 

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73's de Edd

Aug 21, 2015
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Your 9V zener tests good so use it.
With no power applied . . . .ohm from the + of the ORANGE assigned electrolytic filter to see how much resistance there is being to ground.
 
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