[R-390] R390A not working at all

[Flowertime01 at wmconnect.com]

Kurt,
r-390 at mailman.qth.net
While waiting for your copy of the Y2K manual to down load so you have some 
schematics to work with you can start with the eye balls.

The old school house mantra was that receiver worked yesterday. Today it does 
not work there for it has one and only one problem. Method one is eyeball the 
problem to one stage and fix it. Method two was listen to it and isolate it 
to one stage and fix it.

You eyeballed a dead receiver first because most days a tube had died. Next 
was a loose subassembly connector or a broken wire some where on the front 
panel. 50 years later here we have added failed capacitors to the short list. (pun 
there intended). Eyeballing got you past the tubes not being lit. 

Moving the receiver around dropped the ballast tube filament the VFO and BFO 
filaments are not lit. Or the receiver did die back when the ballast tube 
failed and a replacement could not be found. Replacements still are hard to find.

Fix one is a jumper across the ballast tube socket and two new 12 volt 12BA6 
in the receiver one in the VFO socket and one in the BFO socket. The original 
filament string was 24 volts. at 6, 6, 12. Where 12 was dropped by the ballast 
tube to regulate the filament voltage of the two oscillator tubes which were 
6 volts. The new string is 2 12's and a jumper. No trouble you are not on 
military power some where in the war world. Good old USA power is plenty steady 
for the receiver without a ballast tube. Read the Y2K manual for other ways to 
deal with a ballast tube. A resistor will work. You can rewire the IF deck to 
feed 6 volts from the other filament voltage source to power the VFO and BFO.

While every tube may check good you can have a socket or wire problem.
Look at every tube one at a time 
Are the Filaments glowing?
Is the voltage regulator tube glowing?

If these things are not true then you need the schematic to start getting
very local and specific.

R390/A have had / have theses plastic capacitors. About 3/8 dia and 1 1/2 
long.
Most are brown but are called black beauties of death. They crack and go 
shorted.

They are mostly in the IF deck. A couple in the RF deck.
Pull your IF deck and take a look.
If your IF deck still has these old capacitors in them you will need to do 
some testing and replacement. Some Fellows just do every and get it over with. 
However with a dead receiver it is best to find and fix the problem before you 
shotgun a bunch of new ones into the receiver. This is just an aside from the 
eyeball inspection.

If all the tubes are lit then you can start listening to the receiver.

In school, repairmen were taught to listen to a receiver. You can front panel 
a receiver down to a stage or two before you even pulled it out of the rack. 
I would first look in the back of a rack to eye ball the tubes. I liked the 
dark space because I could see the blue glow of the gassy tubes in the dark. 
Once I had the receiver back on the bench in the shop and it had been off and 
cooled down the gassy tubes did not always glow or have enough color to be seen 
in the shop even when shaded. Look at your receiver with the lights off. Set it 
up on one end so you can see the top and bottom in the dark and not be moving 
things around in the dark.

Head phones on.
See the next mail

I have to keep these short. 
We hit a size limit.
And I have had it bumped up already for my long stories.

Roger L. Ruszkowski  AI4NI