Wacky voltage readings


Charles W. Powell
 

I get normal voltage readings at Clk0 and Clk1.  That's where it stops.  Voltage readings are very low on the transformer test points (pins 5,  6, 7, 8) but then I get to the ICs.  Almost all of them, instead of showing ~2.5 - 5 volts on the various pins, show > 11 volts.  The really odd thing is that some of these are in the audio chain, and despite that, I at least have sidetone audio and variable hiss with the volume pot.  I can't for the life of me figure out why this is so high, nearly across the board.  I also know it receives down to at least -73 dBm.  Not great, but it's a start.

I'm working on this for my brother-in-law, and either he's cursed, or the board is.  I've found three faults so far, and there is work to be done on the rest!  The strangest one is that the volume pot appeared to be soldered in place perfectly well.  It turns out, the wiper lead was not making contact with the board for some reason.  Even though I re-flowed the joint and did everything I could to fix it, no luck.  So I put a wire from the wiper lead to the outboard pot connection point and that fixed the first issue.  Second was a burned away trace that I needed to jumper (very inelegantly, above the board, and the third at the toroids.   But the voltage thing puzzles me.  I'm surprised it hasn't gone up in magic smoke yet.

Join QRPLabs@groups.io to automatically receive all group messages.