So last week I said that there was an audio hiss, but no signal on my UBitx v4. I think I may have traced the problem. The capacitor C4 seems to have been mechanically scraped off the board. My surface mounting skills are not up to much. Am I best trying to bridge it with a conventional 100 nf capacitor, try to get some surface mount or get a replacement board.
What are the vendor like at sending out replacement boards? Any idea how much the board would be?

Best wishes

Sean 2e0sfq

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Take two 15-30 watt irons . Heat them both . Hold one om each hand. Place tip of one on one end of part place the tip of the other on the other end of part. Slightly press the tips together and when solder melts lift part off the board. Clean up pads with solder braid. Get some paste flux and put a small amount on the pads.Using tweezers place the new part on pads. Put a small blob of solder on tip of iron place tip on one end of part and pad at the same time (hold the part in place with a small screw driver until solder flows. Repeat exactly for other side of part.
I used this method several times a day for 10 years while working as a repair tech in a manufacturing company.

Hi Sean,

It's no problem to use a conventional part with leads if you want.? You'd just have to be careful that the connections don't stray onto other pads.? If you have room, you can just tape the part down near pads, then push the leads down onto the pads, clip off the excess and then solder.

73,


Mark.

Sean

Glad you may have found it. Sure, bridge any similar value cap you have. You can even temporarily,? or permanently install the leaded cap on top to see if audio is restored.

I have certainly used leaded parts on surface mount boards, its nothing to fret about.

BTW smt caps when you have them tend to be easy to install with their higher mass than many other parts. But use what you have, and enjoy the radio. Good eyes in your discovery.

Curt

开云体育

Just a quick question, is it just for smoothing? Could I get by with just bridging the connection?

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Sean

Rarely can a capacitor be replaced with a short circuit. Often it is blocking DC, or filtering it. Sometimes it can stay open, but likely the cap is necessary. You result seems to say so. See if you can find a similar value cap. Okay to leave the broken one in place, as long as it isn't a DC short.

Curt

Where exactly? is C4? I just can't see it? - neither in the schematic nor on the board?

开云体育

It is on the raduino. I think it smooths the line to the demodulation stage

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Cap is in series, so that's a DC blocking, AC coupling cap from CLK0 on the SI5351.

Regards,
Gary

it is a .1 microFarad (100 nF) dc blocking capacitor for the BFO.? The detector will not work without that signal, and it cannot be just bridged.? I would get a surface mount capacitor to replace it, however a leaded capacitor with the leads kept short would work.? If you go with a leaded capacitor be sure to keep it close and flat to the board so it does not get in the way of the display when it is plugged in.??

If it came from the factory that way, I would contact HF Signals to see if they will send you a new capacitor, if not replace the Raduino board.? If you can solder, then the board shipping will be more than having them send you a replacement capacitor and putting it in yourself.

73
Evan
AC9TU