[time-nuts] 5370B stop trigger not working
jim77742 at gmail.com
Tue Dec 22 07:26:11 EST 2015
I'm beginning to think my 5370B is heading towards a boat anchor.
We (as in all time-nut owners of 5370s) seriously need to research a
replacement part/circuit for the 7061/7062 parts.
On 22 December 2015 at 07:44, Christopher E. Brown <cbrown at woods.net> wrote:
> You might want to re-scope the start and stop channel outputs where they
> cross A4 and
> verify against the front panel labels.
> The signal line crossing A4 that lines up with frontpanel start is start
> and the one that
> lines up with stop is stop.
> I mention this because the A3 board is a carry over from another unit and
> the start/stop
> labeling on the board itself is reversed from the 5370B front panel labels
> and the parts
> list follows the board labeling. So, if you read front panel and lookup
> P/N in list you
> get the wrong one.
> The safe thing is to follow back from the output crossing A4 that is
> failing and
> physically pull the hybrid and read the P/N on the mounting frame. It
> should be a metal
> can in a screw together frame, the part is socketed.
> Once the A3 is out, do not remove the screws in frame, they just clamp the
> frame to part.
> Whole thing is held in by the collar on the pot shaft.
> For a 5370B
> 5088-7061 (start channel hybrid)
> 5088-7062 (stop channel hybrid)
> the manual lists it reversed, and they are actually different parts (not
> just diff
> mounting frames) with crossed up triggers.
> 7061 (actual start manual lists as stop) is the one that usually fails and
> is almost
> impossible to find. Took me several years (and the help of another nut
> with a parts unit)
> to get a working one. 7062 is much easier to find.
> On 12/13/2015 11:26 AM, Jim Palfreyman wrote:
> > Oops yes! I looked up the wrong item. I meant A3U1 which is 5088-7061
> > Jim
> > On Sunday, 13 December 2015, Cok <Electronico at jpkoning.nl> wrote:
> >> According to the partlist A4U1 and A4U2 seems to be TL072CP opamps.
> >>> jim77742 at gmail.com said:
> >>>> I have gone through the troubleshooting process from the manual and it
> >>>> seems
> >>>> to point to A4U2 (Schmidt trigger) being faulty.
> >>> I'd put a scope on it to check.
> >>> Before I dive into this, does anyone have any advice? Most important
> >>>> the Schmidt trigger - where do I get one?
> >>> You need more info - the manufacturer's part number or something like
> >>> that.
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