[Amps] alpha 91b help

Rick Stealey rstealey at hotmail.com
Wed Oct 15 14:46:37 EDT 2008



If that is a resistor that is in series with the primary of the power transformer that is supposed to be shorted out after a second or so it is very likely that you have a condition in either the transformer (not too likely) or in the power supply such as a shorted electrolytic or other device.
If it were me, I would make some meaurements in the B+ area first.  The filter caps are most suspicious.  If you find they are ok, then begin the process of elimination.  Use logic.  I'd first unhook the transformer HV leads and make sure the transformer is not shorted, etc.  

I think you likely have a serious case of high current in the power supply though.  I did some ohms law, and about 4 amps of startup current would be 160 watts through that R.  But a fuse that is overloaded twice its rating probably will not open.  I bought some fuses recently and checked specs on them and if I remember correctly a typical fuse will last many, perhaps tens of seconds at a 2 X overload.  I doubt that 15 watt R would last that long.  So that fuse is likely not serving any purpose !

Rick  K2XT




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