Doepfer

--- bakis sirros <syrros@ath.forthnet.gr> wrote:
> From: "bakis sirros" <syrros@ath.forthnet.gr>
> To: <synth_freak_2000@yahoo.com>
> Subject: Fw: [Doepfer_a100] Re: Flat LED's
> Date: Fri, 4 Oct 2002 15:54:46 +0300
> 
> 
> ----- Original Message -----
> From: "Dieter Doepfer" <hardware@doepfer.de>
> To: "Bakis Sirros" <syrros@ath.forthnet.gr>
> Sent: Friday, October 04, 2002 1:51 PM
> Subject: AW: [Doepfer_a100] Re: Flat LED's
> 
> 
> > Dear Bakis,
> >
> > please forward this answer to the group to
> eliminate misunderstandings:
> >
> > 1. Concerning A-140:
> >
> > There was no revision of the A-140 since the first
> version. The reason for
> > different resistor appearance may be the rotation
> or 4/5 ring coding (plus
> > tolerance ring). For some resistor applications
> (e.g. pull up or pull down
> > resistors) the value is not very important (e.g.
> 8k2 or 12k or 15k instead
> of
> > the 10k printed on the pcb).
> >
> > The transistors BC547, BC548 and BC549 are
> replacement types (npn types).
> Same
> > is valid for BC557, BC558 and BC559 (pnp types).
> Very often the parts list
> of
> > the service manual reads e.g. "Q1, Q2, Q3 = BC547C
> or BC548C or BC549C".
> On the
> > silk screen only one value (e.g. BC547) appears as
> there is not enough
> space.
> >
> > The transistors in the A-140 are used only for
> switching applications. So
> there
> > is definitely no difference in the modules
> behaviour if there is a BC547
> or
> > BC549 used in the module.
> >
> > 2. LEDs:
> >
> > When we started the A-100 in 1995 flat LEDs
> TLSR3200 or TLSR3201
> manufactured by
> > the German company "Telefunken" were used. These
> LEDs are no longer
> available as
> > Telefunken has stopped the production and as far
> as I know the company
> > Telefunken went bankrupt as is no longer on the
> market as a electronic
> parts
> > manufacturer. We purchased all flat TLSR3200
> Telefunken LEDs we could find
> as
> > soon as we heard about the problems with
> Telefunken. As far as I remember
> the
> > flat Telefunken LEDs lasted about until 1997/1998.
> Because of the problems
> with
> > these special flat LEDs we decided to use standard
> "round" LEDs to avoid
> > problems in the future as for these parts many
> different manufacturers are
> > available.
> >
> >
> > Best wishes
> > Dieter Doepfer
> > Doepfer Musikelektronik GmbH
> >
> 


=====
synthfreak(parallel worlds)
athens-greece
[Doepfer_a100] group owner-moderator

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Although I'm grateful for Dieter's reply concerning the 
'history' of the LEDs on the A-100 modules, I have to 
say that I received the first batch of modules to become 
available in '95, and the A-140 and A-145 BOTH have 
the 'bead-type' red LEDs, and NOT the orangey flat 
style ones. 

So there you go...  





Sean.
analogueman@dsl.pipex.com


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