[R-390] Dead 6MHz and 10MHz

[Barry Hauser]

Hi Fraser

Your earlier post mentioned that this is an R-390A, right?

There's no need for major disassembly.  The crystals are right on top of the 
crystal oscillator module under the cover.  I think it's one screw to remove 
on top of the rectangular box - which is the oven, -- and there may be one 
along the side -- facing the rear panel.  I forget if there's an access hold 
through the rear paenl to get at that screw which may just be into an open 
slot whereby it just needs to be loosened so the thing lifts off.  Be 
careful as there are the leads to supply current to the oven which is built 
into the top that you will be removing.  Some versions may have a plug 
disconnect, but if not there's about enough slack to lay it to one side.  If 
there is no access hole for the side/back screw, you can get at it with an 
offset screwdriver or possibly one of those mini-ratchet handles with a 
phillips bit in it.  It might already be loose.  I'm going from memory. 
It's been a while.

Have no idea what you mean about removing the front panel, gears etc. You 
don't have to remove the crystal oscillator module to work on the 
crystals -- or the trimmers -- everything is right on top.

Sometimes it's just a bit of oxidation on the crystal pins or socket 
terminals.  Some contracts have a rather poor style of terminals made of 
dimpled stampings and may be loose.  (found this with the '67 EAC's)  Remove 
the xtal and stake the loose terminals with a sharp, small blade screwdriver 
lightly, so as to reduce the pin opening a bit.  Use some DeOxit on the pins 
and sockets. Make sure the pins are clean and not hazed over with oxide.

The problem might also be the trimmers on the top of the xtal deck -- in 
front of the oven (rectangular box).  The one crystal that's not operative 
may have oxidation in/on the associated trimmer.  Just turn a bit and turn 
back.  If one is frozen, use some DeOxit and let it sit.  You can either 
refer to the manual or the labeling of the trimmer caps to ID the correct 
trimmer and xtal.

You should have the slotted switch on the rear panel labeled "ovens" set on 
off.  You can operate the receiver with the cover off and tap lightly on the 
crystals to localize any intermittents.  It's not a bad idea to remove, 
De-Oxit and re-insert all of the crystals while you have it opened up.

Actually, they're one of the easiest things to get at.

hope this helps
Barry





----- Original Message ----- 
From: "Fraser Bonnett" <FraserBonnett at adelphia.net>
To: <r-390 at mailman.qth.net>
Sent: Sunday, August 28, 2005 9:35 AM
Subject: Re: [R-390] Dead 6MHz and 10MHz


> >Upon further investigation I have no Calibration signals on 6, 10, 23
>
> OK, so these bands share the same crystal in the Crystal OSC module.  Is 
> it
> possible to get the cover off the crystal oven, without going through the
> steps outlined in the Tech manual involving removing the from panel, 
> playing
> w/ the gears etc?
>
> Fraser
>
> _____________________________________________________________
> R-390 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/r-390
> Help: http://mailman.qth.net/faq.htm
> Post: mailto:R-390 at mailman.qth.net
> Unsubscribe: http://mailman.qth.net/mailman/options/r-390
>