Terry -
This display is an indication that the Lo Synthesizer (Bands up through
14 MHz) is unlocked.
Do NOT touch the +10V adjustment pot (last one of a row of pots across
the top of the power supply card), just behind the front panel on the
right side. Changing this pot at all requires a complete realignment of
the transceiver. Also make sure you don't accidently bump this pot
while the transceiver is open as this can cause the same problem. It is
a single turn pot and very touchy.
The first step to take with a TR-7, or any solid-state radio with
plug-in cards, is to open it up and re-seat all cards in their sockets.
90+% of the problems in the TR-7 can be solved this way. There just
isn't enough voltage and/or current through those connectors to burn
through ANY oxidation or corrosion.
Unfortunately the majority of the frequency determining cards are
located under the DR-7 display board, which can be a challenge to remove
and replace without damaging something if you've never done it before.
Actually it's very easy and safe, after you've done it a time or two.
Remove the power connectors around the sides of the board, and note
that they are NOT keyed in any way. A Magic Marker stripe along both
halves at one end is a good idea. They generally cannot be connected to
the wrong ones because of lead lengths, but a photo of the board before
disassembly is a good idea for later reference. There is one screw left
of center that must be removed, and a coax lead that comes up through a
hole in the board that must be disconnected to allow removal. There is
a row of connector pins in the left rear corner, another row about
midway down the left side, and two groups of three about an inch in from
the back edge. These are the points of resistance when you start to
pull up on the card to remove it. The display also fits into a recess
at the front panel that prevents it from coming straight up and out.
The process is to lift up on the left rear and left edge of the board to
unplug those rows of pins until they release, then lift the back of the
board up and back to release the display. Again, much harder to
describe than do.
Once the DR-7 board is out, pull up each of the smaller cards just
enough to move them in the sockets and then push back down. It's not
necessary to remove the card or disconnect any of the coax cables.
There are two small holes in the top of each card to accept a card
puller. You can make a puller by bending a piece of wire coat-hanger
into a "squared U" shape with small bends at the open end of the "U" to
mate with these holes. It's also possible to use a small screwdriver to
insert into each hole in turn and pry gently against the aluminum
shields between cards to loosen the card in the socket.
Once all the cards and connectors have been re-seated, re-install the
DR-7. First, examine the long pins on the bottom of the card to make
certain they are all straight and aligned properly. Then insert the
display into the recess at the panel, and lower the rear of the card
_making certain that the pins are ALL mating with the appropriate
sockets_ and press it down into place. Check carefully as you go that
the pins are actually into the sockets by looking under edges and
through holes in the board.
Turn the unit back on and hopefully it will be working properly again.
If not, then further troubleshooting will be necessary.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs
<www.k4oah.com>
[EMAIL PROTECTED] wrote:
My TR-7 has developed a frequency problem. When turned on with the
bandswitch on 160m, the frequency readout showed a frequency of
17600-17800 Khz and was jittery. After warmup of a half hour or so, it
would start working and and show 1870 Khz like it should. Now, it
doesn't show 1870 khz at all and stays in the 17600-17800 range even
after warm up. Neither the RX or TX is working.
However when I push the RCT button and go to my R-7 for frequency
control, everything is working correctly and I am on 1870 Khz and the
RX and TX is fine. When I switch to transmit the TR-7 readout shows
1870 Khz. When I go to RX then it goes back to 17600-17800 Khz. So
where should I start looking in the TR-7 to find the problem? Is this
a known problem that someone else has experienced or a new one? Any
help someone could offer would be appreciated.
Terry,
W8NJR
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