Fernando is having trouble with posts here and to John Hermanson
bouncing. Here at his request is his latest.
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Hola Moose,
Thanks for answering :-)
"Machines take by surprise with great frequency" - Alan Turing.
Moose wrote:
>
> Classic symptoms of two things.
>
> 1. Failing battery. Although most characteristic of non-silver oxide
> batteries, I could see this happening with silver oxides at just the
> right stage in their useful lives. Especially with the 303/357, with
> its long slow decline discharger curve (as opposed to earlier 357
> later 357/303).
>
> The why is simple. Battery load in metering, lighting test button,
> operating self timer, etc. is quite low. AND, none of these but the
> battery check cares much about the voltage.
>
> BUT, battery drain holding the second curtain open during exposure is
> quite high. AND, the exposure circuit is very picky about voltage, as
> insufficient voltage could mean mis-exposure. Voltage is checked just
> as maximum strain is put on the battery, it fails the test and the
> camera aborts the exposure.
>
> Unfortunately, the battery check light on the OM-4 series bodies is
> not very good. Check with a voltmeter.
Done. My new Renata 357 batteries measured 1.5 dead-on.
just checlked a couple of almost new 357s
> If voltage is below 1.5v, try another set. It doesn't matter if the
> batteries are "new", as manufacturing defects or time in the
> distribution channel crop up from time to time.
>
> 2. Poor electrical contacts in the battery circuit. This is most
> commonly loose screws holding the bottom plate on, but can be
> oil/corrosion where the plate makes contact or elsewhere in the circuit.
>
Most probably this one may be the cause. Glad to have ruled out the
memory clear button and the self-timer left On.
Removed the bottom cap after tightening to check if it was loose. It
admitted a less than one degree of tightening, not much.
Removed the batteries, measured them, cleaned both at each one's
surface, inspected the batteries chamber and everything looked quite clean.
Put the batteries again, tightened firmly and fired: it failed ... red
1/60, fired again: it worked. Continued to shoot both with winder2 and
shutter release button, it didn't fail. Even took my time to check
shutter speeds using my TV set. Loaded the RDPIII. Shall wait until it
happens again ... :-(
> The why is similar to above. At low current, there is little enough
> resistance through the problem spot that everything seems normal. With
> higher current, the voltage loss across the poor connection is great
> enough to lower the voltage too much for shutter operation.
>
OhM rules !!
> If truly fresh batteries and tightening the bottom plate screws don't
> cure the symptoms,
How do I tighten those screws? Which one are they, btw? The black screws
which can be seen from the outside of the camera, at the farthest right
and left of the bottom plate - or something hidden inside the battery
chamber?
> take the plate off and clean the bottom of the body casting around
> where the screw holes are, including use of a rough eraser, fine
> sandpaper or some such on at least one hole.
>
Damn! - that might wear the paint off the black screws !! And I'd need a
crosspoint [destornillador] !.
You're talking about my 'new' OM 4Ti :-)
BTW, this failure made me remember of very recent one I had.
Strangely enough, I hadn't use my power amplifier since maybe the
beginning of June (nor had I used the 4Ti, which arrived on those days -
that is almost the whole winter).
On August 24, I turned it On. No sound from the left loudspeaker,
everything else looked Ok.
Did the usual troubleshooting: it was the power amp, no doubt.
Time to buy a new one? Calmed down and thought a little (yes, I'm able
to think very clearly under stress).
At its back, the Bryston 4B SST has three switches, only one of them was
suppressed in the newer 4B SST², the ground lift. The other two switch
the amp from balanced to single-ended inputs, and from individual
channels to bridged mode. Switched those switches (amp *Off*) up and
down several times. Most probable, the balanced - single-ended selector
switch got dirt or moisten (we have cold an humid winters here). At
first, left channel didn't sound as loud as it should, repeated the
procedure and it's now as good as ever.
And all their screws are perfectly black ;-)
Fernando.
--- does the idiomatic expression 'loose screws' mean something for
English speaking people?
>
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--
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