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Re: [OM] OM 4 old vs new circuit

Subject: Re: [OM] OM 4 old vs new circuit
From: clintonr@xxxxxxxxxxxxxxxx
Date: Mon, 29 Jan 2001 00:06:03 -0600
Hi, John --

There were four versions of the main circuit in the original OM-4 --
five, if you include the circuit used in the OM-4T, which can be
installed in an OM-4.

The first main circuit included several jumpers and resistors external
to the main flex which were incorporated into the design of the second
version.  Also, when the second version of the main circuit was
incorporated, the LCD driver circuit was also improved.  It is possible
with adaptation to combine an original main circuit with a new LCD
driver, or to combine a new/improved main circuit with an original LCD
driver.

The third main circuit was (as well as I recall) available only with new
bodies -- it could not be purchased separately as a repair part, though
it was available to Olympus along with the whole front casting, I
believe.  The wires from the body to the main flex were visibly smaller
on this version, which is extremely rare (it appears to have been an
interim "fix" to reduce battery drain).

The fourth version had only slightly different wiring than the second --
a small sub-circuit was attached underneath the end of the circuit with
the two VR arrays.  It is the best version, vis a vis battery drain.

After the OM-4T was introduced, production on version 4 of the OM-4's
circuit was discontinued.  Once the stock of OM-4 main circuits was
depleted, OM-4T circuits were adapted to replace them.  To do this,
however, the original LCD driver (if it was present) had to be replaced
with the newer style LCD driver, along with the SV circuit which
attaches the main circuit to the body.

Before anyone asks, I've no idea what production codes or serial numbers
would show which circuit was used -- it simply never came up during
service!

Clint

John Hermanson wrote:
> 
> Clint will know this better than I.  there was an intermediate board which
> came out before the T version.  Latest, low drain version was not available
> during last of 4 production.
> 
> John  Hermanson
> ___________________________________
> Camtech, Olympus Service since 1977.
> 21 South Lane,  Huntington NY 11743-4714
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> ___________________________________
> ----- Original Message -----
> From: "Tom Scales" <tscales@xxxxxxxxxxxxx>
> To: <olympus@xxxxxxxxxxxxxxx>
> Sent: Sunday, January 28, 2001 10:57 AM
> Subject: Re: [OM] OM 4 old vs new circuit
> 
> | Interesting question. I was under the impression that the last runs of the
> | OM-4 included the new circuit off the production line.  Anyone confirm or
> | deny?
> |
> | Tom
> | ----- Original Message -----
> | From: "John A. Lind" <jlind@xxxxxxxxxxx>
> |
> |
> | > At 21:42 1/26/01, Jim Timpe wrote:
> | > >Off after 30 seconds means new circuit.  Or dead battery.
> | >
> | > I'm a bit confused on this one.
> | >
> | > Does "new" mean an OM-4 with an OM-4T circuit, or was there a revision
> | made
> | > during OM-4 production?
> | >
> | > -- John
> |
> |
> |
> 
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