New findings:
1) EMC model 105 multimeter, after calibration and ruling out parallax
error, measures both the Renata 357 in use *and* a new pair at normal
temperature and humidity - well above 1.5. They are, in fact, rated
1.55V but I measured all four at a little less than 1.6. A value of
1.58V could be a good guess.
2) The smallest Philips screwdriver I could buy in town, fits Ok into
*three* of the bottom screws. And no, I didn't find any of those three
anywhere near loose, and didn't want to overtorque them, neither unscrew
them. BUT I found that the screw at the left, the one near the battery
cap is damaged by overtorque. It's not obvious, paint is Ok - but my
tiny Plilips screwdriver won't fit into it, and quickly snaps out of it,
if I try to screw it with the faintest clockwise torque. This one could
be loose, or not - I cannot tell. It's damaged.
3) No, I'm not getting lockup on every shot - but when it locks up, I'm
not able to know when will it stop locking.
Sending this one to the list, and redundantly to John and to Moose from
my three email addresses (different SMTPs)
TIA
Fernando
--- out 'till Friday at 5 pm local time.
John Hermanson wrote:
> New silver oxide are usually 1.55 - 1.59V. If you get good battery
> check and still get lockup ON EVERY SHOT, then there is a more serious
> problem. The only screws to tighten are the 4 on the bottom. The hole on
> the leading edge is supposed to be there.
> ___________________________________
> John Hermanson | CPS, Inc.
> 21 South Ln., Huntington NY 11743
> 631-424-2121 | www.zuiko.com
> Olympus OM Service since 1977
> Gallery: www.zuiko.com/album/index.html
>
>
> Moose wrote:
>
>> Fernando is having trouble with posts here and to John Hermanson
>> bouncing. Here at his request is his latest.
>> =========================================================
>> 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?
>>
>>>
>>>
>>>
>>
--
Dr. Fernando González Gentile M.D.
Av.L.P.Ponce 1526B - 11600 Montevideo, Uruguay.
Phone: +598 2 7084858
Fax: +598 2 7087396
<fgnzalez@xxxxxxxxxxxxx>
--
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