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All,
The other week my U3s stopped working, it coincided with a nearby thunderstorm. I had been tx'ing wspr and qrss at the time, noticed spots had ceased, checked U3s and just a blank blue screen, the QLG2 lights were all still blinking.
So far, replaced MCU with new one from Hans, changed screen in case this one had burnt out, listened to 27MHz crystal, checked all wiring secure. I have the OCXO fitted, this still heats up.?
I believe that the clock on the SI5351 chip on board the OCXO has stopped working, I will probe the outputs to the MCU and PA this weekend, presumably if the 5351A unit is toast then the mcu will not output any text to screen or output power. Filter relay board fitted.
There's very little that can go wrong on the U3s unlike some other kits, I did have the plain 5351A board but gave it away so unable to do a quick swap and check.
Other than the above any?thought's on other suggestions to look at.
Andy
--
The universe is made up of Protons, Neutrons, Electrons but contains only one M0RON.

Ok,?
Probed the clock outputs, nothing, pin 13, sc has nearly 5v on it while pin 14 is very low. Pin 18, pll has 3.3v. Possibly Q7 died??
Andy?
--
The universe is made up of Protons, Neutrons, Electrons but contains only one M0RON.

I had a similar (maybe lightning) problem with a QCX+5W.? ?In that case I replaced the Si 5351 A-B-G? several times as well as the QCX demodulator chip (you don't have)? without getting it going.? ?

I wondered if the first 2 5351A B GT 's? were miss sold pre-programmed ones so tried one from another source.? I used my spare CPU chip too the third time of praying and it all worked again.? I've not swapped the CPU back yet but suppose I ought to get round to it.??

?

The chip that definitely did work was?

Taking my own advice I just swapped the CPU that had been involved in the problem back into the set.? ? ?After set-up It all works fine so probably only the 5351 was damaged.

I'm going to order the basic 5351 synthesiser board, I have 3 mcu chips here, tried all but no change so I'll change the 5351 as they are cheap. In the meantime I'll play with sdrconnect for wspr receiving.
Andy
--
The universe is made up of Protons, Neutrons, Electrons but contains only one M0RON.

As an update I think I've found the issue.?
Replaced the screen, no change, replaced the ocxo with a bog standard si5351 synth board, still not working but I have garbage on the screen, so progress but still not working. Listened for 20MHz crystal, all good, listened for the 27MHz crystal, nothing.?
So I think that the problem was a damaged ocxo board followed by a non functioning crystal in the replacement synth board. 2 separate problems at different times but in the same repair. I'll pull the crystal later and order a replacement.?

--
The universe is made up of Protons, Neutrons, Electrons but contains only one M0RON.