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

[Adam Vaughn]

Great post. When I first got my R-390A, I searched for info online, and found Chuck Rippel's sadly-gone R-390A site. Fortunately, it has been archived, and can be found here:


https://web.archive.org/web/20090204020515/http://www.r390a.com/


Following instructions there, I replaced both C-553 and C-549 (which affects audio, IIRC) with orange drops, and restuffed both filter cap cans before applying power to my R-390A. I also checked the infamous 3TF7 ballast tube and found its filament to be open, so I replaced it (I won't get into the myriad replacement options here).

Another tip I would give to new R-390A owners is to use a current-metered variac to bring up voltage slowly to the rig upon first turn-on, while watching the meter to make sure the set isn't drawing too much power. In addition, this protects the filament of said ballast tube, as well as the microswitch on the function control. Of course, they should be sure to turn said function switch to AGC before doing so, as the antenna relay will make buzzing noises if the variac is used with the switch set to Standby.
-Adam
 

-- 
Adam Vaughn
Collector of old computers, video game systems, radios and other electronic equipment... 
Visit my page at http://www.electronixandmore.com/adam/index.html
 
On 04/25/16, Tisha Hayes<tisha.hayes at gmail.com> wrote:
 
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**
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