It's hard to beat the TenTec guys for service. I had a very similiar
experience when I owned a Corsair II. Had a problem (don't remember
the specifics, but I called the TenTec service dept. and they put a
few transistors in the mail for me (no cost to me...absolutely free).
I am sure my Corsair had been owned by at least three other hams
before I bought it, but that didn't seem to make any difference to
TenTec. I don't think the other companies would go that far for you!
Mike
K5UX
--- dslosty <dslosty@pipeline.com> wrote:
>
To: <tentec@contesting.com>
> Date: Mon, 17 Jul 2000 00:42:32 -0700
> From: dslosty <dslosty@pipeline.com>
> Subject: [TenTec] Corsair II failure
>
> Just had the first failure in my Corsair II.
> The digital readout either doesn't come on or comes
> on after 5 minutes or so. When the rig is warm and if it is turned
> off and then on, the readout will not reappear. All digits are
> blanked
> out,
> with the exception of the decimal point with is fed directly by
> Vcc.
> Also the readout will occasionally freeze and not update.
>
> I think I've traced the problem to the MC68705P3 on the logic
> board.
> When the malfunction occurs, the processor's output enable 1 and
> enable
> 2
> signals vanish. Also the keyer functions stop working. With no
> enable
> signals being sent to the LED driver chips, they obviously stop
> working.
> Thus the processor is probably at fault. All supply votages are
> normal.
>
> Have others seen this problem? Is a failure of the MC68705P3
> common?
> Hopefully Ten-Tec still stocks these since the onboard firmware
> must
> be custom.
>
> 73,
> Doug/WA1TUT
>
> ----------
>
> As a continuation of the above, here's what I found:
>
> A call to Ten-Tec was very useful.
> Their service manager mentioned that they'd had trouble with one of
> the
> electrolytics near the processor chip. He wasn't sure which one,
> but the
> hint was extremely helpful.
>
> I got out my logic probe and found that the processor chip was
> keeping
> its reset output line high. This reset high was being sent to the
> input
> counter/divider chips and was stopping the enable pulses to the LED
> driver chips.
>
> Sure enough, the 2.2 mf electrolytic cap on the processor's reset
> line
> was bad. Since the only 2.2 mf cap I could find was a non-polarized
> type
> typically for audio crossover networks, I used it. Hey, ya gotta
> make do
> at times! Nevertheless it works fine and the trouble is solved. I
> may
> replace that cap with a standard polarized one, but since the one I
>
> installed was rated at 50 volts, it shouldn't be a problem.
>
> Thanks to all the folks who emailed me with suggestions.
> Their response was appreciated.
>
> Thanks again, Ten-Tec!
>
> 73,
> Doug/WA1TUT
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