the counter on the omni D series is nothing but a frequency counter.
there's four boards in the counter module
1. the main counter board
2. the input shaper and amplifier and preset board
3. the display board
4. the time base
since the display is multiplexed, having all the digits roll tells me
the multiplexing is working find. If there was a problem with it, you
would see one (maybe more) of the same segments fail.
the counter needs signal from the vfo amp board. Make sure there's
enough gain there. Most likely there is as this board also provides
the drive to the transmitter. Remove then reseat the board. This board
is on the bottom of the rig. Watch that speaker wire!
remove then clean with some dexoit (just a smige) on the rca cable
that goes into the counter. It's on the left as you face the front of
the radio.
if that does not fix the problem, you need to open the counter up.
Follow the instructions in the manual. Make sure you power the radio
down. Then place a piece of heavy cardboard down on top of the board
containing the two transistors with the heat sinks. The heatsinks are
connected to the +12 volt supply and it's really easy to short them
out with the top of the counter box. Ask me how I know!
when you got that done, remove the rca cable from the input board and
then the single nut holding the board down.(the board is actually
sideways)
the board plugs into the counter display. clean the contacts, using a
small smige of contact cleaner.
reassemble and try for proper function.
If not...
pull the time base out (same deal as the input board) and clean it's
contacts too. I don't believe that is the problem since a kaput time
base would not allow the display to roll.
if you're comfortable with the following, gently and I mean gently
remove the LSI counter chip. MAKE SURE YOU NOTE WHERE PIN 1 IS BEFORE
YOU REMOVE THE CHIP!
Pull the chip out and then reset it. Do this a couple of times to
break off any corrosion the pins may have. Be careful! This chip is
very hard to come by and is very expensive. DO NOT use any cleaning
stuff on the pins.
To get to the display board, you have to remove the front of the
radio. the display board routes signals from the input shaper and the
time base to the main counter board.
If you have a scope, you can follow the input signal into the main
counter board. It should be a nice clean square wave going into the
counter chip. Scope it out right at the input of the counter's LSI
chip. Use a 10:1 probe.
I think that should do it.
These radios are great! I've got four of them in various forms. I have
a omni A that's just a hoot to work cw with.
good luck!
Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
http://www.theheathkitshop.com/
J e e p
o|||||||o
A man with one clock knows what time it is. A man with two clocks is
never sure.
On Oct 27, 2009, at 6:41 PM, Stuart Rohre wrote:
Omni D problem. Check the solder joints for the display board. Sounds
like a cold joint somewhere there. Use a high power magnifier and a
strong light. If in doubt touch up all less than perfect looking solder
joints.
-Stuart Rohre
K5KVH
John Peters wrote:
Hi MIKE
I have had a trouble with the digital display on my OMNI D.
the display is unstable for a fer minutes
and then it is o kay--- for a short while then goes showing all
numbers (unstable) again. then
a few minutes it goes okay with a little tapping at times....
Then runs o kay the rest of the day....
do you have anything for a fix?????
hope so ??
thanks John K2kot c ya
On Oct 27, 2009, at 11:16 AM, Mike Bryce wrote:
every now and then, especially when it's kind of cool in my shack,
when I turn the omni VII on, there's no display.
I do get the leds by the switches to light
I just leave it on and within a few minutes, it decides to light up.
cycling power does nothing to help
However, if the room is warm, then I've never had the trouble. It
seems as though the cool temperatures is preventing something from
firing the display backlight
mike
Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
http://www.theheathkitshop.com/
On Oct 27, 2009, at 5:50 AM, Hulett, Russell wrote:
Yesterday, turned on the Omni VII and nothing happened. No lights or
anything, like power disconnected. The fuse was ok, voltage on the
supply connector checked fine. After several tries, the display
backlight came on but the radio didn't "boot". Cycling the power
switch once more caused the radio to startup normally. All memory
intact, radio works normally. Anyone else experienced anything like
this?
73, Curt KB5JO
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