[R-390] Troubleshooting Question

[rodger_adams at yahoo.com]

Hey All,

 

I have an R-390 (non A) that has developed the following problem.  When I
turn it on, it warms up and works normally for about a minute or so.  Then
without warning, it shuts down.  Lights out, no B+, etc.  It does the exact
same thing every time I turn it on.  Any thoughts on where to begin
troubleshooting?  How to easily isolate the B+ from the modules, etc. ?  For
the minute that it's on after warming up, the B+ reads 185 volts.  

 

Thanks in advance for any advice.

 

Rodger