RX dies after several hours of operating

General discussion and support for the Peaberry SDR V2.

RX dies after several hours of operating

Postby n9seo » Mon Jan 05, 2015 2:19 pm

Hello,
In another post I had low output I found that I had some more adjusting to do. I was able to get output on this pretty good over the last week. Let me just preface this with some other external issues I had discovered over the weekend. After a weekend of operating the peaberry, I noticed that we had some MAINS issues. So I guess this is a possibility that the MAINS dropped a phase over the weekend and possibly the pb took a hit. The Utility company did repair the bad neutral connector on their side of the meter. I did take some minor electronics damage but the PB took some hours after before the RX croaked

My only real issue with my PB at this time is after several hours of use the RX still locks up or dies. The LED still will work as expected between modes. I can try to capture a recording when this happens in HDSDR if it does again. Im sure it will but probably not until I log several hours on it again and have it die in mid qso on the rx side. I can transmit a signal ALL day however it only seems to be isolated to the RX side. I need to get a better understanding but for the most part im just focusing on the first page of the schematic as I believe that is all mostly RX side.

I am starting to examine the pin outputs on u6 when it dies. Im not sure but somehow I started tapping in this area last night when it died lightly around U66 and the audio opamp and it sprung into life temp. I have reflowed the solder and sucked out the excess with some wick to be sure. The PSoc does not die nor does the tuning functionatity. its just like the audio output on the rx side just vanishes for some reason.

Does anyone have a quick recheck list like softrock for voltage points for u6 or the rx section other than schematic or any other suggestion? Im not afraid to try a cheap replacement next time i get a digikey order going, but I'd like to understand better how to troubleshoot this section next time it dies. I can surely replace those chips or pull them and clean the pads but I'd like to narrow it down first before I start applying heat to the board.

73 Kayne
Peaberry SDR v2 30/20/17/15m
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Re: RX dies after several hours of operating

Postby W4MMP » Mon Jan 05, 2015 3:26 pm

Hi Kayne,

The first place I would look is at Q1. Make sure there is 5v on the gate in receive mode. Does receive sensitivity slowly decrease or simply suddenly die?
73
Ron / W4MMP
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Re: RX dies after several hours of operating

Postby W4MMP » Mon Jan 05, 2015 7:46 pm

Hi,
Sorry, I just re-read you last post. May I suggest not tapping but take wooden tooth pick a lightly press on the legs of U6 and U5. Follow the receive path the entire way though to and including the PSoC.

Just a thought.
73
Ron / W4MMP
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Re: RX dies after several hours of operating

Postby AE9RB » Mon Jan 05, 2015 10:35 pm

Sounds like thermal changes are causing a bad solder joint to open up. Poking the board like you did can help find it. No amount of busy work, er I mean, multimeter testing is going to reveal the problem since once you put the test probe on the bad pin you have closed the broken circuit.
73 David AE9RB
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Re: RX dies after several hours of operating

Postby n9seo » Tue Jan 06, 2015 2:06 am

Yea I do not get much warning. I am replying to both you guys.


W4mmp, Ok will try the old toothpick thing. When it dies the rx chain starts to crackle for about 5-10 secs then its dead. Q1 presently has 5v in working rx.

The solder joints are what I was thinking but will have to keep poking at it until it stops i guess. I do know that it seems like both chips are powered at least when it happens. Will try both of your suggestions. Thanks again.

73 Kayne
Peaberry SDR v2 30/20/17/15m
n9seo
 
Posts: 16
Joined: Sun Feb 16, 2014 2:04 am
Location: Austin, Travis County, TX EM10

Re: RX dies after several hours of operating

Postby n9seo » Fri Jan 16, 2015 3:02 pm

Hello,

Turns out my issue was external to the rig. I neglected to account for a loose neutral connection on the MAINS line that only showed issue during windy gusts. When this would happen the mains on that curcuit would surge to about 140VAC. Luckily for me no ham gear was damaged, cept maybe the peaberry. I guess it was broadband rfi that did it as evidenced by the large RED Splotches on the waterfall. I guess I can blame it on this but its worked rather solid since the utility company replaced the connector. Only a couple of server power supplies here took some damage in the transformer. After that and retouching the solder it seems solid. :D

73 Kayne
Peaberry SDR v2 30/20/17/15m
n9seo
 
Posts: 16
Joined: Sun Feb 16, 2014 2:04 am
Location: Austin, Travis County, TX EM10


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