[R-390] Before you attach power to your newly acquired R-390A

[Tisha Hayes]

There are a few steps that you absolutely must do before you power up any
untested R-390A receiver;

1.  Replace C553. This is on the IF deck and keeps B+ off of the mechanical
filters. When this cap shorts out it will blow out the input coil on the
mechanical filters. As quick as you would rotate the bandwidth switch you
would destroy every filter in turn. You should never-ever see B+ on the
filter side of this capacitor.

2. Check the power supply filter capacitors. These are the plug-in can-type
capacitors on the audio deck. and are several capacitors inside of each
can. These age badly (wine turning in to vinegar) and while you may have
some success in reforming the capacitors so they do not draw excessive
current they will never come back to their full capacitance or ESR values.
If your radio has the B+ fuse mod (in an external holder on the back) the
bad caps will keep blowing out this fuse. If you do not have a B+ fuse you
can end up burning up a transformer, rectifier or power supply choke.

There are at least another dozen steps you should be taking before powering
up the radio. These first two are ones that keep the components from
releasing their "magic smoke packets" and making what could be a fairly
easy restoration turn in to a major rebuild/ overhaul with unobtanium parts.

*Ms. Tisha Hayes, AA4HA*
*"*There are many who live in the mountains and behave as if they were in **the
town; they are wasting their time.*
* It is possible to be a solitary in one's mind while living in a crowd;
and it is possible for those who are **solitary to live in the crowd of
their own thoughts.*"*
**-Amma Syncletica of Alexandria**