[R-390] R390 Band Switch Alignment

[Flowertime01 at wmconnect.com]

John,

Thank you for the archive link. I need that and did not know it.

Mark Huss,

Thank you for putting up the post from my soap box.

Dan Merz,

You may have a band switch alignment problem where the 4, 5, 6, 7 setting is 
not
making good contact in one of the wafer sections.

As you have Cal tones on each band, the oscillators and crystals are good.
The only things in common with the four bands being weak is the RF switch and 
the set of tuning coils. The rack, the slugs, the switch, Check the slugs and 
rack from the tops side before you pull the RF deck. Do peak the second 
crystal deck caps.

One additional idea before you go into the bottom of the RF deck. 
Pull the slug rack by releasing the two springs (one front and one rear) on 
the rack
and lift it out of the slides. Insert a #1 Philips screwdriver down the slug 
hole and remove the 6x32 screw that holds each coil can in place. The coil 
cans plug into the deck with several pin contacts. Wiggle them up free and clean 
the contacts and pins. These contacts have been known to oxidize like tube and 
crystal pins and sockets.

Mark Huss put up a soap box of mine about why we should pull the RF deck and 
do the band switch alignment by eye. It looks like you have a classic case of 
band switch just not quite making on one position. Some time if you tune from 
high to low or low to high the switch will make for you going one way and not 
the other. Some time you can do 8, 7, 6, 7 and get the 7 Mhz to work. some 
times you can do 3, 4, 5, 4 and get the 4Mhz to work. These are clues the switch 
lash is to far out and needs adjustment. May as well get your self a some 
deoxit or other favorite switch contact cleaner and go after the band switch. As 
long as you have to pull the RF deck, you may as well do a full PM under there 
and be done with for a couple years.

Plan to clean the switch, set the switch adjustment, give the deck a bath, 
and check the state of the capacitors under the deck. If you have some brown 
beauties in there, change them out.  Just do not jump in real fast. work with the 
receiver, Use it a while, work on the other parts of the alignment and see 
how it works out. After you get all the other easy top side items fixed up, then 
plan a Saturday to do the RF deck. By that time you will have gotten the 
tools and materiel together for the task.