Author Topic: MR16 not working  (Read 5998 times)

Offline btdb1969

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MR16 not working
« on: March 15, 2012, »
I built my first MR16, Im using a power supply from a computer. The power supply seems to be working correctly but I have no power LED. I have checked all the solder joints, looked for anthing backwards or incorrectly installed but everything looks right to me. Any help would be very much appreciated. I attached a few photos .
Bill A.
Maysville, Ga

Offline Jeffl

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Re: MR16 not working
« Reply #1 on: March 15, 2012, »
No power LED could be that the power LED is in backwards.  Have you tried sending DMX to the board?  If you don't get it, I would take some photos out in the daylight and from multiple angles.

Offline btdb1969

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Re: MR16 not working
« Reply #2 on: March 15, 2012, »
I dont get DMX, I'll take better pictures tomorrow
Bill A.
Maysville, Ga

Offline btdb1969

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Re: MR16 not working
« Reply #3 on: March 16, 2012, »
here are the pictures taken in daylight
Bill A.
Maysville, Ga

Offline Jeffl

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Re: MR16 not working
« Reply #4 on: March 16, 2012, »
I would test a volt meter setting at the voltage regulator (out)  for starters.  I assume it's in right but can't see with the heat sink.

Offline tbone321

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Re: MR16 not working
« Reply #5 on: March 16, 2012, »
I would first check to make sure that it is the regulator in the regulator position and not a mosfet since they look the same. 
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Offline mmais68569

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Re: MR16 not working
« Reply #6 on: March 16, 2012, »
Looks like on the POS side of the incoming power that you may have gotten it to hot & possible melted plastic over the metal on the board.

           Mike

Offline btdb1969

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Re: MR16 not working
« Reply #7 on: March 16, 2012, »
The regulator is in correct and it is the regulator not the mosfet but since im not real good at the technical part, which pins should I touch on the regulator to check it?
Bill A.
Maysville, Ga

Offline Jeffl

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Re: MR16 not working
« Reply #8 on: March 16, 2012, »
Here is the data sheet on the regulator.  See page 6 for pin outs.  Put the ground on the ground pin.  Check both the input and output pins for voltage to see if the power is coming in and going out.

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Offline Jeffl

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Re: MR16 not working
« Reply #9 on: March 16, 2012, »
This is the only spot I see that looks questionable but one on of the two legs would be affected which should not affect it as they are both soldered into the same pad.


Offline btdb1969

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Re: MR16 not working
« Reply #10 on: March 16, 2012, »
@Jeffl
    I cleaned up that spot, desoldered it and then resoldered...It still doesnt work
Bill A.
Maysville, Ga

Offline Jeffl

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Re: MR16 not working
« Reply #11 on: March 16, 2012, »
How is the voltage at the regulator?

Just and FYI from my experience.  A solder station really works well for these spades.  I crank the heat up to about 390c and use a wide tip that holds a lot of heat.  This way it heats them up quickly.  The extended period of heating with low power units can kill parts.

Offline btdb1969

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Re: MR16 not working
« Reply #12 on: March 16, 2012, »
I show 12 on the input side, and 0 on the output side...so I take it that it should show 5 on the output side??
...thanks for all the help.
« Last Edit: March 16, 2012, by btdb1969 »
Bill A.
Maysville, Ga

Offline Jeffl

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Re: MR16 not working
« Reply #13 on: March 16, 2012, »
Work time is over.  It's play time now. 

You should have positive voltage on the out as long as the voltage is good on the in.  My thought is the voltage regulator is the problem.  I'd like to see others chime in that are more experienced than I before you go getting to crazy trying to fix things just in case it could be something else.

Offline rm357

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MR16 not working
« Reply #14 on: March 17, 2012, »
If you have 12v on one side and don't have 5v on the other, there are only a few things that can cause this.

1. Bad 7805
2. Got one of the mosfets by mistake - if they get mixed together it's hard to tell them apart.
3. Short on the board.
4. 7805 in backwards?

Since this is easy, I'd remove the three chips and see if you still have 0v - one of them could be bad and shorting out the board. I didn't see any solder bridges.

Next, I'd bite the bullet and try to remove the 7805. It's not going to easy though and you are going to need either a really good solder sucker or solder wick... I'd start with just the heatsink first...

RM
Robert
Warner Robins, Georgia, USA