[TenTec] Orion II repair

[Gary J FollettDukes HiFi]

I still don’t know.

Here is an update o the rather strange behavior:

I already swapped power distribution board, button board and CPU board. A different CPU board operates properly in the radio. perfectly.

Here is the sequence:
1) Cold startup  normal boot up sequence, receives signals, none of the encoders except VFO’s work, none of the pushbuttons work.
2) Connect to N4PY software and connect, most functions work but not necessarily correctly. Tuning rate is very slow and some buttons do not do  what they should.
3) Shut down for maybe 30 minutes.
4)  Cold startup  normal boot up sequence, receives signals, none of the encoders except VFO’s work, none of the pushbuttons work.
5) Wait 15 minutes, everything works fine.
6) Shut down for maybe 30 minutes.
7)  Cold startup  normal boot up sequence, receives signals, none of the encoders except VFO’s work, none of the pushbuttons work.
8) Wait 15 minutes, everything works fine.

Now, if I operate the encoders while the radio is ignoring them, then wait out the 15 minutes, the radio responds just as if I had just taken those actions. That is, if I turn the volume down while the radio is not responding, the volume will drop once the radio starts working. Ditto for all other encoders. So data is getting to the I/O controller, just not being sent to the CPU. In this state, the actions of pushbuttons are NOT saved, however.
One thing that is different about the VFO encoders, both of which always work, and the 6 small encoders is that the VFO encoders are pull high devices operating from the R5 volt supply. The 6 small encoders are pull down devices with outboard pulp resistors also operating from the R5 volt supply.

If I operate the encoders in the first fractions of a second after boot up, before the S meter makes is normal bump swing to the right, the encoders work but stop working after that bump. 

The delay to normal operation is pretty repeatable. It acts as if there is a high resistance somewhere and a capacitors is charging up to enable the CPU to see data that is in the I/O controller.

I really doubt that this is a thermal issue or a CPU or I/O controller issue. I am contemplating simply replacing all of the capacitors on the CPU board.

Gary



> On Aug 5, 2016, at 11:09 AM, Katz Ajamas <ajamas.rn at gmail.com> wrote:
> 
> So what was wrong? CPU power on reset problem? Please share.
> 73, -Bob ah7i
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