No rebuild is required.
remove the top case.
there is a cover over the display, (counter) remove this cover
looking down into the counter and display there are three pcbs. the
main counter on the bottom, to your left if the preamp and preset
counter. to your right is the time base. The main logic board is 80441,
the preset-amp board is 80465, the time base is 80442 and the display
is 80440.
both of these cards plug into the display board which in turn plugs
into the main counter.
now, assuming the radio is on frequency when the problem occurs, we
then know the pto is working correctly.
the display scheme used by ten tec (and others at the time) is nothing
more than a frequency counter.
the make the counter work as a digital dial, they cheat. This cheating
is done by presetting the first one or two digits on the counter's
display.
when you loose the preset, the counter is, well, goofy, it's still
counting, but it's not displaying the entire readout correctly.
what you see i.e. 1, on 7mhz, 91 on 10 mhz and 0900 on 14 mhz are in
fact the presets. Remember, the actual frequency is 9 mhz away from the
5.0 to 21.0 mhz pto frequencies.
without the preset, the display on 7.040 would read 6.040. by "adding"
a extra "1" to the display, we end up show 7.040. depending on the
band, the preset may be added to or subtracted from the actual
frequency being produced by the pto.
now, this is important, even if the preset is wrong or missing,
PROVIDED the pto is working, the display would change and track the
pto's frequency so if you're looking at 6.040, moving up 100 khz would
produce 6.140.
so, why don't you see the correct display?
The small pcb to the left of the display contains the presets and input
amplifier. this pcb also squares up the sine wave coming from the vfo.
Try these fixes
1. verify that in fact, when your display is goofy that you hve the
signal in from the vfo. You will need a scope or counter. On the left
side of the counter box, there is a small RCA cable, that's from the
vfo amplifier. Is the signal there? if not, you won't see the correct
display. Move back and see if the signal is at the vfo amplifier (board
#80454) If the radio receives and transmits, then no signal at the vfo
amp means the mixers all work, the problem must be on the vfo amplifier
board.
2. If you have signal from the connector going into the counter, remove
the preamp/preset pcb and reset the pcb contacts. Do the same for the
time base as well. ( you will need to remove the long brace that goes
from side to side to ease removal of the counter pcbs)
3. while you're working on the time base, scope the store, gate and
load pins.
4. the main counter IC is in a socket, very very very carefully remove
it and then reset it. breaks off the oxide on the pins.
5. The main counter pcb is double sided but NO plated holes. touch up
every solder joint you can get at.
because the display, preset/amp and time base plug into the main logic
board, any one hohum connection will stop the counter in its tracks.
From the description you have given, it sounds like a solder joint or
just a flaky contact.
Let us know what you find out.
mike... wb8vge
Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
http://www.seslogic.com
http://www.theheathkitshop.com/
On Apr 12, 2006, at 12:46 AM, Tod Glenn wrote:
>
> On Apr 11, 2006, at 8:31 PM, lw3ewz wrote:
>
>> Dear friends
>> i love this rig... but i have a problem
>>
>> I need te solution at my display problen in my omni d series c
>>
>> The display look 1.000 in 7 mhz band. 91.000 in 10 mhz, 09000 in
>> 14 mhz and 21 mhz and sudenly the display works fine
>>
>> what is the problem? and what is the fix or solution?
>>
>> Sometimes the display works fine and sudenly works bad again..
>>
>> thanks in advance
>
>
> Sounds like you need to rebuild the PTO.
>
> ----
> Tod Glenn
> N7JQW
> NAQCC #1283
> SKCC #1444
> FISTS #12134
> ARCI #12420
> n7jqw@cordite.com
>
>
>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
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