[TenTec] Omni D Strange Behavior

[Mike Bryce]

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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>
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