[TenTec] Omni 6 Logic Board Failure

[Dr. Gerald N. Johnson]

 From a distance we have NO way to tell if its the EPROM. But a whole 
string of Kenwoods had a problem with EPROM sockets so the factory 
solution was to solder the EPROM in after pulling the socket. An 
intermittent EPROM socket that contains program will drive a micro batty 
instantly. Changes the program in random ways. Changes the lengths of 
jumps in the code, changes the code registers, changes constants, makes 
it really BAAAAAAD!.

Now we also remember the controller that's used for the display in the 
Corsair II goes ape when the on board electrolytic(s) get old. Those on 
the board of the earliest Omni VI are nearly that old.

If the processor is in a socket its as suspect as the ROM and the RAM 
sockets. If the RAM goes making errors because of low voltage storage it 
won't keep the radio working the same. Might be a simple as changing 
modes from power down to power up or powering up in transmit on a 
different band than the user has ever used. And that could come from a 
bad power supply bypass or circuit solder connection. I KNOW these kinds 
of faults have caused controllers and PCs to run amuck. In vintage Apple 
II+ that ran badly, often all that was needed was to SEAT all the ICs on 
the boards. They were in sockets and thermal cycling caused them to 
rise. Pushing them down was often enough cleaning of the pins to make 
the work like new. Good sockets have gold plating or gold inlays, they 
cost a buck or two apiece ten or twenty years ago. But sockets with tin 
plating cost a dime apiece and work almost as good in the short run, but 
not necessarily in the long run.

I had a customer with a modem problem that only showed up when they left 
the office windows open late in the evening and it got foggy overnight. 
Then the $1200 modem failed in the morning. A spare always got it 
working and that failed modem took a trip to the factory for a few 
hundred bucks. Finally I examined one of the failed modems and found the 
bottom of the CMOS logic board was smeared all over with flux, they 
hadn't cleaned the flux off and it was hygroscopic. I cleaned the 
remains of the flux off and those modems didn't fail again before they 
became too obsolete to be practical.

Then there's the Paragon boards that just need to be soldered that were 
soldered by hand, and sometimes some connections didn't get done well it 
seems. I don't know the Omni VI is the same, but I suspect it could be 
part of the problem and the time it takes the $50 an hour tech to solder 
all the connections you don't want to pay for.

73, Jerry, K0CQ

On 1/17/2011 7:13 PM, NL7VL wrote:
>> Point is, the ONLY custom chip is the EPROM, I have a shoe box full,
>> but don't have the TenTec Omni VI code.
>
> OK - gotcha. We'll see what happens. But is it the EPROM? I didn't see
> where anyone said it was the problem for sure.
>