On Sat, 26 Nov 2016 09:21:27 +0000, Jim Lesurf wrote:
In article , Woody
wrote:
I have put a copy at
http://jcgl.orpheusweb.co.uk/temp/Unknown.jpeg (about 3MB file)
Can anyone recogise this and say what it is?
Well it clearly a reel to reel (probably) quarter track tape recorder
with built-in amplifers. However the type of diagram is quite specific
in that it has a component map at the top, and a quick bit of Googling
of diagrams of all of the well known German manufacturers suggests it
might be Uher.
Ah! That may be an interesting clue. Thanks.
I don't recall ever seeing any Uher kit or diagrams. And - so far as I
recall - no Uher items in the anechoic chamber. However there could
easily have been some in the past which were discarded before I took
over the chamber.
The sheet has part of one corner torn off. I have been wondering if it
initially had one or more attached sheets which gave more info. e.g.
What we see looks like a tape-deck based system. But doesn't seem to
have an oscillator for bias/erasure. So maybe there were more diagrams
and/or sheets which actually identified the unit.
Near the middle of the diagram, C21/L201 and C121/L202 look
suspiciously like link winding coupled bias traps with the link windings
in parallel connected to what seems to be the bias/erase oscillator
transistor emitter (TS201) driving the erase head windings (K2 and K102).
It's quite obvious that this is a domestic tape recorder using K1 and
K101 for both playback and record head functions. Whilst using the same
head for both recording and playback functions reduces costs, it does
compromise the performance in one or both of these seperate functions
since you need a wide gapped lo-Z wound head optimised for recording and
a narrow gapped Hi-Z wound head for best replay performance (being able
to monitor the just recorded signal coming back from the tape *isn't* the
primary consideration with a separate record and replay head setup, even
though that happens to be a very welcome feature).
What makes interpretation of the circuitry tricky is the logic behind
the way the complex switching is labelled. There are tables on the LHS of
the diagram that attempt to describe the cryptic labelling of the
functions of each switch in the form of a puzzle worthy of the detective
skills ascribed to the eponymous Mr Sherlock Holmes.
I've no doubt, given enough motivation to do so, there's enough
information coded into those tables for the dedicated sleuth to work it
all out. Since I'm not in the least bit motivated, I'm not going to "burn
up" any more of my sleuthing skills than I've already squandered other
than to say it's safe to assume what the switches will do when analysing
the circuitry from each possible assumed state of playback or recording
circuit functioning (along with the compounding influences of speed and
mode settings such as mono recording on tracks 1 or 4 or 2 and 3 and
"duoplay"-presumably dubbing track 1 or 4 playback to track 3 or 2
recording whilst mixing in from a mic or line input source).
In short, it does look rather like the whole of the tape recorder
circuitry is actually laid out in that one diagram. The lack of a model
number reference however, does suggest that this is one of many pages out
of a workshop service manual. Unless you strike it lucky by this being
seen by someone who actually used such a service manual, I doubt you'll
be able to pin it down to better than a guess as to it being a Phillips
or Grundig domestic 4 track tape recorder circuit diagram.
--
Johnny B Good
Anyone recognise this diagram?
Hybrid Mode
