[time-nuts] Resoration of 5065A - continued...
paulswedb at gmail.com
Mon Sep 11 09:36:56 EDT 2017
I would simply slap a 741 into position to see how it behaves.
Also check those zeners for +/- 14.7V. They go bad.
On Mon, Sep 11, 2017 at 5:56 AM, Ulf Kylenfall via time-nuts <
time-nuts at febo.com> wrote:
> Continuing my efforts to fix the 5065A...
> There was something wrong in the A7 (AC Amplifier assembly).
> DC balance of the input stage was completely off-scale
> and one of the 1854-0023 transistors had an open junction.Luckily I had a
> small supply of them but I also discovered that
> the OP-Amps were old "seven of nines" (709).
> There are several different manuals floating around on the internet,
> and the hard copy that I have shows two different versions
> of A7. One with 709 and one using 741 that is also different
> in terms of circuit design and layout.
> I am considering redesigning A7 using modern CAD and also
> purchasing boards from a professional vendor, but first I would like
> to know if anyone has tried both versions and if there are any
> improvements. The modern 741-version uses DIP-socketed
> OP-Amps so that version could be tried with even better
> Ulf Kylenfall SM6GXV
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