TS-590SG Reduced transmit power, Reboots. Known Problem. Easy Fix.

20190216  Incident – TS590SG rebooted once while transmitting.   Later under testing into a dummy load, power was limited around 50 watts in CW mode, sometimes more, sometimes less.  The reboot occurred once or twice.  The lack of power affected all bands.

Reason for failure – the 25amp fuse holders and other connectors on the power cable for the TS590 oxidize over time and can cause significant power loss over time.  When the total current carrying capacity of the power cord assembly is reduced due to oxidation and gradual loss of the necessary gas tight metal to metal contact, the rig reduces power output or may reboot.

Recovery Actions Needed –  remove power cable, inspect, wipe all connectors clean, pull out, clean fuse contacts, or simply reseat the fuses.  Inspect Johnson power pole connectors and insure all connectors are seated fully.  When I inspected the fuse blades, they looked shiny and clean, but the reseat worked.  The power pole connectors are known to be subject to oxidation and losses.

Result of maintenance actions:  Restoration of normal operation.

Other – the power limiting and reboot behavior made me wonder if  a serious electronic failure, e.g. of the final mosfet transistor amplifier, occurred.  Other accounts on the web may likewise be misleading, if only because fragments of information can be  misleading.

The  problems caused by power loss in the power supply cable are not widely advertised but known to TS590 owners and amply documented online if you know where to look – but misleading information is also present.  See: https://groups.io/g/TS-590/s  or on QRZ.  Before too long I was in contact with two hams in particular with direct experience with the problem. CE3DNP and W2JDB helped me zero in on the problem. This has been characterized as a “classic” TS590SG fuse problem.  Thanks guys – saved me a lot of time and effort!



~ by marksun on February 17, 2019.

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