That sounds like the Si5351 is dead or heavily loaded. It's worth checking what it is connected to first before replacement. If it is drawing lots of current that might be because one of the IO / output pins is being pulled down or is shorted to ground or Vdd. Have a look at the schematic and trace all lines off and look for shorts etc.
New ones aren't terribly expensive or difficult to replace despite looking evil however. RS sell 5 off for ?5 approx with next day delivery. To get it off, just flood both sides of the IC with solder alternately and lift off with tweezers, then clean up the pads with some chemwick braid. Soldering a new one on, I would refer to many of the tutorials on YouTube.
I've got to say one thing though and that is that I'm not actually that happy with the dual diode dropper implementation on the Si5351A power supply. The part is rated to max 3.6V and I measured the loaded voltage at 3.8V. I consequentially replaced the two diodes with an MCP1700-3302 low dropout regulator (bodged in) and changed C2 for a 1uF ceramic 0805 cap when I was constructing it. That keeps it solidly at 3.3V.?
Thing here is that the MCP1700 will keep the max current into the Si5351A at a manageable 200mA if something goes wrong. 7805 will throw an entire amp and a half into it.
Chris
M0XTE
On Fri, 27 Jul 2018, at 00:45,
m0icr@... wrote:
A quick check of other components running very very hot include the Si5351 (oh dear!) and the D1 and D2.
73 Carl M0ICR
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