Author Topic: New build - red light & no green light  (Read 4940 times)

Offline kenlmcse

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Re: New build - red light & no green light
« Reply #15 on: May 15, 2011, »
it is more than the led, it is not sending a data stream during a sequence. Correct me if I am wrong, the leds are simply indicators of what is happening, red means powered up, green means data flow.

I took multiple pics, here are the ones that are the least blury. I tried to get the solders at multiple angles. The solder joints that look like they have extra solder are the ones i hit again after looking through a magnifying glass.

Thanks everyone!


Offline tbone321

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Re: New build - red light & no green light
« Reply #16 on: May 15, 2011, »
How hot do you have your iron set to.  It looks like it may be a little to cool.
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Offline kenlmcse

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Re: New build - red light & no green light
« Reply #17 on: May 15, 2011, »
Same as I always do, But my tip is looking bad. Anyway about 3/4 of the way.

Here is my unit
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Offline bisquit476

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Re: New build - red light & no green light
« Reply #18 on: May 15, 2011, »
I've circled what looks like a solder bridge in the attached picture, maybe something to look at,

Bill

Offline kenlmcse

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Re: New build - red light & no green light
« Reply #19 on: May 16, 2011, »
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I've circled what looks like a solder bridge in the attached picture, maybe something to look at,

Bill

Extra solder from when I re-hit all the joints to ensure I soldered right. I left my soldering iron on so the tip got dirty. I should have cleaned it before checking all the joints. I paid the price by having extra solder on some of the joints. I cleaned up the excess.....

I really do think I either have a bad capacitor or the mosfit transistor is bad. One of the capacitors reads 5+ and 5- on both sides, the other one does not show the 5-. It is the one that comes out of the mosfit transistor.

If someone wants to read the voltage on both sides of their capacitors and let me know if the read 5v across it and if they read voltage from their mosfit. The outside framework is 5+, one of the outer lugs is also 5+, the other outer is 5-. the center lug should be the gate, it should read 5+, I am not getting that. But I could be wrong on my understanding of how a mosfit works.

My guess is  I burned something out when I re-hit the joints with a dirty soldering iron. I think I had an original problem of a cold solder joint that I made worse with too much heat.

By the way, I replaced all three chips which is why I am now going down this road.

Thanks everyone!



Offline n1ist

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Re: New build - red light & no green light
« Reply #20 on: May 16, 2011, »
I'm not quite clear on what you mean by 5-.  Measure voltages with the black probe of your meter to ground and use the red probe for measurements.  In the dongle, there are two grounds; the PC side which is used for everything up to the input of the DC/DC converter (a good place to probe this is the top lead of the 4.7K resistor between the USB module and the oscillator) and the isolated ground after the converter (a good place to find this is the top end of the 0.1uF capacitor next to the 6N137)

If the MOSFET is off or not working, I would not expect to see 5V after it (or on the output of the DC/DC converter module).  That certainly would cause the lack of output data and the green light being off.  Note that this is a P-channel FET; pulling the gate to ground will turn it on.

There are a number of leads on the backside that look a bit long; component leads should be clipped a little closer to the board.  I agree with Tbone321; it looks like your soldering iron wasn't hot enough, especially for the pins of the USB  module.  Pin 28 of the PIC also looks like it needs some touching up.

/mike
« Last Edit: May 16, 2011, by n1ist »

Offline kenlmcse

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Re: New build - red light & no green light
« Reply #21 on: May 16, 2011, »
Thanks you just gave me something that I cannot wait to get home from work to test. I was using the grn post of the usb module as ground and using the top of the mosfit for positive. I will try testing with the resitor.

Also, I cannot wait to ground it out to see what happens. 

Thanks!