Hi Gary, I did the ground on RFC505 and no change except that the
voltage goes very low of course going through a 100K resistor. The
frequency counter shows 1.3 MHz on the output of the VCO when it
is on 10 or 15 meters. When I switch to 14 MHz it pops up to 65
MHz but it is not connect to the translator board just plugged
into my extenders.? I did a voltage check at the test point off of
CR515, CR516, CR517, and CR518 and here is what I got, Way off.
1.5 MHZ 21.24 VDC Looks like it should be 3 volts. the photocopy
is heard to read.
14.0 MHz 21.20 VDC Looks like it should be maybe 15 volts
21.0 MHZ 21.17 VDC and looks like it should be 6 Volts
29.5 MHZ 21.15 VDC and looks like it should be 14.5 volts
Maybe I am way off Gary but hope that maybe that helps. Almost
looks like something it shorted? I don't know where to go next so
any help appreciated. Thanks.
73, Jim VE1RB
On 2024-12-30 13:42, Gary Follett via
groups.io wrote:
toggle quoted message
Show quoted text
That is WAY too high!!
The maximum that should be seen at this point is ~15 volts,
the high end of 10 meters. 20 volts here would push the VCO to
its maximum frequency, if it is running at all.?
Is there any RF signal coming out of the VCO? You may have
answered this previously but I seem to have forgotten the
answer. If there IS RF, here, what is its frequency?
Something is telling the PLL phase detector to put out a
voltage thinking that the frequency is too low, which is why the
voltage on RFC505 is so high.
Can you short RFC505 cold end to ground? This SHOULD make the
VCO, if it is operating, go to the low end of its range in
frequency. This point is fed via a 100K resistor from U504B so
this will not hurt anything.
Gary
W0DVN
PS: Not taking into account C516 and C517, I had previously
stated that voltage across the tuning diodes depended one the
voltage at Q504 Drain. This was an error on my part. Those two
capacitors isolate the DC on the tuning diodes from the Drain of
the oscillator FET.
Cn you short?
Gary
I just checked that voltage again with the band switch
on 10 meters and the DC voltage at that RFC505 is 20.52
DC. Hope that helps.
Jim VE1RB
On Sun, Dec 29, 2024
at 8:37?PM Gary Follett via ??<xntrick1948= [email protected]>
wrote:
What is the voltage on RFC 505?
Gary
W0DVN
Worked
on the VCO board today and founds that the
5 volt regulator is working just fine 5.02
VDC. So am thinking about it trying to
decide what I check next. Might make a
chart of voltages on the transistors from
the working one and compare to the non
working section.
73, Jim Ve1RB
On Sat,
Dec 28, 2024 at 11:08?PM Gary Follett
via ??<xntrick1948= [email protected]>
wrote:
The power supply that is the
subject of this issue is the 7805
regulator on the VCO board. That is
the one that denies power to just the
one VCO (high bands, in this case)
when it fails.
Regards,
Gary
W0DVN
On Dec 28, 2024, at
8:28?PM, Tony N5DIM < tony@...> wrote:
The WB4HFN
website has a section with
great information related to
that power supply board. I
just used it to resurrect a
TR7 that was DOA. Good luck.
73 Tony N5DIM?
On
Dec 28, 2024, at
5:52?PM, Gary Follett
via??<xntrick1948=[email protected]> wrote:
?Sounds
like you are on the
right track. Don¡¯t
ocelot the electrolytic
capacitors on that
supply as well.
Gary
W0DVN
Gary,
I found a few
minutes to
work on the
TR7 and
discovered
that the high
VCO is not
working at
all. It does
have the 10
vdc supply
switch?on it
but I don't
know if that
reulagor?is
working or
not. I will
check it out
but have to
work on
getting the
metal shield
off. I Hope
that is the
problem but I
will work on
it maybe
tomorrow.
Thanks for all
your help.
73, Jim
VE1RB
On Fri, Dec 27, 2024 at 9:06?PM Gary Follett via ??<xntrick1948= [email protected]>
wrote:
It is
worth asking,
did the
failure of
your VCO board
(displaying
51.950) occur
on its own?
That is to
ask, did the
radio work
properly and
then just fail
or has it, as
long as you
have had it,
always
operated with
this fault??
If it
once worked
for you and
then failed,
then it would
make sense to
see what gets
disconnected
if those pins
are not in
line ?and look
for a way that
same thing
could happen
without the
pin alignment
problem.
The pin
alignment fix
is pretty easy
though, if the
board
alignment is
the cause. It
just SOUNDS
difficult.
That
whole DR7 was
always a
source of
issues due to
its complexity
and difficulty
of
installation.
I don¡¯t know
how a DR7
could even
endure the
stresses of
removal and
reinsertion
more than
once!
Gary?
W0DVN
Thanks
Tom. I printed
that off but
hope that is
not the
problem.
73, Jim
VE1RB
In 2010
there was a
thread
regarding the
Drake TR-7
display
showing
51950.0 on the
old retired
Drakelist.
The
thread is
archived at?
Please
click the link
so the owner
knows that we
find the
archive
useful.
Hope this
helps.
Tom, AG9X
================?
Below are
the posts from
Brian Koontz
WA3ITE, Jim
Shorney NU0C
and Garey
Barrell K4OAH
(SK)?
(just in
case Drake
TR-7 DR-7
problems
outlive the??site)
Re:
[Drakelist]
Almost there:
TR-7 display
issues --
FIXED!
Brian Koontz
Fri, 30 Jul
2010 20:36:54
-0700
Well, the TR-7
from hell is
now a fully
operational
TR-7 from
hell!
In preparation
for some
signal
tracing, I
decided to
extend the
DR-7
board using
the extenders
I have.? To do
this, you have
to unmount the
two voltage
regulators
mounted to the
chassis, and
jumper the
connector
farthest to
the right. ?(I
didn't bother
connecting the
up/down band
buttons.) ?Lo
and behold,
the display
worked!?
Some further
investigation
revealed that
the chassis
has warped
over
the years, so
the two
3-prong
connectors on
the VCO board
were no
longer in a
horizontal
line.? So I
was determined
to make sure
the
board was
fully seated
on all the
connectors.
To do this, I
had to drop
the front
panel.? Not a
major chore,
just
one knob to
remove (the
band knob) and
6 side screws.
With that now
out of the
way, it was an
easy job to
determine if
all the pins
were
where they
belonged.? The
only snag was
that the front
panel, when
canted
downwards,
angles the PTO
can upwards.?
So you have to
hold the
front panel
perpendicular
and steady
with slight
downward
pressure to
fully seat the
board.? Once
all the pins
were visually
confirmed to
be
seated, I
remounted the
front panel,
reattached the
regulators and
all
the
connectors,
and fired the
rig up.?
Everything now
seems to work!
It turns out
the original
DR-7 board was
indeed
defective as
well
(possibly
because it had
been seated
incorrectly).?
And a visual
confirmation
from topside
indicates the
chassis is,
indeed,
warped:
The screw hole
is misaligned
with the
mounting hole
in the board.?
So, for
archival
purposes in
case anyone
else decides
to search for
this problem:
?If the
display if
fixed on
"51950", one
possible cause
is that one or
more DR-7
pins, possibly
the VCO pins,
are not
correctly
seated.? The
best solution
is to drop the
front panel
and
confirm
visually that
the pins are
fully seated.
Now it's time
to get on the
air!
??--Brian/WA3ITE
=================?
Jim
Shorney Fri,
30 Jul 2010
23:17:58 -0700
On Fri, 30 Jul
2010 20:40:52
-0500, Brian
Koontz wrote:
>Well, the
TR-7 from hell
is now a fully
operational
TR-7 from
hell!
>
>Now it's
time to get on
the air!
Congratulations, Brian! You have been assimilated into the collective.
Resistance is
futile.
73
-Jim
=================
?
Garey
Barrell ?k4oah@...?via ?
Sat, Jul 31,
2010, 8:34?AM
to drakelist
Brian Koontz
wrote:
> Some
further
investigation
revealed that
the chassis
has warped
over
> the
years, so the
two 3-prong
connectors on
the VCO board
were no
> longer in
a horizontal
line.? So I
was determined
to make sure
the
> board was
fully seated
on all the
connectors.
>
>
>
> So, for
archival
purposes in
case anyone
else decides
to search for
> this
problem: ?If
the display is
fixed on
"51950", one
possible cause
> is that
one or more
DR-7 pins,
possibly the
VCO pins, are
not
> correctly
seated.? The
best solution
is to drop the
front panel
and
> confirm
visually that
the pins are
fully seated.
>
Brian -
Congratulations!! ? It's always nice when one 'comes together'.
Just as an
aside, someone
suggested
earlier (and
correctly)
that the
"51950"
problem may
indicate a
loss of the
500 kHz
reference
signal.?
You might find
it interesting
that the
left-most
three pin
connector on
the VCO board
is the 500 kHz
reference
signal!
Those pins on
the bottom of
the DR-7 are
ALWAYS a
problem, ya'
just
can't see
'em!!
Your 'trials'
have been an
interesting
'trip' for
others, thanks
for
documenting it
for us all.
73, Garey -
K4OAH
Glen Allen, VA
Drake 2-B,
4-B,
C-Line&
?TR-4/C
Service
Supplement CDs
<>
=================
?
Search
terms to make
this post
easier to
find:? Drake
TR-7 TR7 DR-7
DR7 display
frozen locked
stuck ?
51950??
51,950?? 51
950?? 5195?
51950.0 ?
51,950.0 ? 51
950 0
???
|
