[R-390] R-391 problem

[Paul Anderson]

Also check the B+ voltage level before leaving the radio on for long -
if the resistors or a couple of other components under the AF or PS
decks are fried, you can get high B+ which could harm other parts in
the radio.

The B+ is supposed to be 180V, and there is a test spot on one side
panel or the other (the side with the AF deck).  Be careful you don't
short to ground - it is somewhat easy to do.  Use a good meter with
good leads and again, be careful!

Once you know you're not frying B+, if you leave the radio on, the
tubes will get warm even if you can't see the filaments heat up, so
that is another way to check.

Paul


On Tue, Nov 17, 2009 at 10:16 PM, Barry <n4buq at knology.net> wrote:
> Hi Mark,
>
> Check the continuity of the pins of RT412 (the 3TF7).  If it is open, then
> those other tubes will not work either.
>
> BTW, the 3TF7 normally doesn't "light up".  It may glow faintly when the
> radio first starts, but then usually will drop back to just barely visible.
>
> Barry - N4BUQ
>
>
>> Hi Everyone,
>>
>> I wrote in a couple of months ago about a R-391 that a found at a yard
>> sale, today I powered up the radio and it looks like three tubes did not
>> light up.V508 beat frequency osc 5749, RT512 voltage regulator 3TF7 and
>> V701 vfo tube 5749. I tried to tune the radio to an am station but only
>> got static. does anyone have any ideas? Thanks.
>>
>> Mark
>
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