Help: Keeping my Flex5000a alive

cfclaver

Hi Flexers!

I desperately need help in recovering my Flex5000a. At the moment it is indicating he following on TX:

1) "High SWR" - band independent
2) No power out - I believe the radio is shutting down
3) Anomalous high input voltage - indicates 24V, at idle voltage indicates 13.7V
4) Radio fails bias level calibration - shows high current, >2A, with drive bias - think this is a bogus reading - drive transistors are new.

How did I get here?

The radio suddenly showed poor output on 6m - only 50%. I could smell something hot coming from the radio. I opened the radio and could see the bridging capacitors, C121 and C122, on the input the final matching transformer were burnt. These were replaced and carbonized material cleaned out, but still only 50% output on 6m.

I have replaced the final and river transistors with new parts. Radio had produced full 100W+ output on all bands except 6m.

While probing with my oscilloscope I accidentally grounded VDD on the matching transformer coming out of the driver stage. Thereafter the radio exhibited the failure mode(s) described above.

My current guess is that the shorting fried the AD converter chip on the PA board that provide the digitization of the voltage and FWD/REV power levels. ANY HELP IS APPRECIATED.

Alternatively, is there anyone still servicing the Flex5000a? Anyone have a 5000a available for parts?

This is a fantastic radio and I would hate to loose it.

Thanks!
Chuck
de NJ6D / N7KU

Trucker

Troy Radio services legacy Flex radios.

http://www.troyradio.net/

cfclaver

My Flex 5000a is now in the hands of Toby at Troy Radio services. I will report back when he finishes his diagnostics.