Gentlemen; Interesting and helpful dialog.? Thank you.? Steve, I didn't go down the path you describe too much because i had the plug and play cable.? I will look at that again to understand your testing process better.? I will keep it on file for next time.
But, the good news is the ARB-704 is back on line.? I traced the issue to a bad transistor.? Transistor Q1 (2n3904).? I was compounding my issue by having the wrong schematic.? The schematic that came in the 704 manual I received with the unit was not the schematic for my version.? Attached is the correct schematic.? I did call MFJ/Ameritron Group and talked with Rob.? He told me that often the large transistors with the heat sinks go bad (Q2 and Q3 (2n6740)).? They seemed to check out okay in my unit.
Once I replaced Q1 all was well.? I did not determine why Q1 failed but was pleased that after replacing it and powering things up it did not fail again.?
I believe that completes the loop on this repair.? I really appreciate the dialog and advice I received and hope my posting will be there for the next one faced with this or a similar 704 issue.? Thank you all for your interest and help.
73 Harrison N1FAM
