[TenTec] Orion II repair

[Gary J FollettDukes HiFi]

There  is some new information.

The A/B switch, when held for 2 seconds, is supposed to change the “A” or “B” on the display and this in turn makes the band select buttons select the band directly. It is supposed to default to “A” I think. Mine defaults to “B”.

If I wait the 15 minutes, and the encoders start to work, I can use the A/B to select “A” but upon restart, the default becomes “B”, which is incorrect.

I think the 15 minutes, a rather consistent number, may be a timeout for the interrupt lines.

It would appear that something is pulling the A/B switch line low, but it is not the switch itself. The switch works fine once the timeout takes place.

I am now looking at the 74HC154 4-to-16 line decoder/demultiplexer.

More to come…

Gary



> On Aug 8, 2016, at 3:29 PM, Stuart Rohre <rohre at arlut.utexas.edu> wrote:
> 
> Gary, before you shotgun all the capacitors, look at all the solder joints for the affected boards with a high intensity light, and a magnifier. A head mount magnifier with light may work, but I often use and independent high intesity Halogen light we bought for troubleshooting.
> 
> I am betting on one or more bad solder joints.  How old is this radio? Are you the first owner?
> 
> Stuart Rohre
> K5KVH
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