From: Olaf Kaluza
Ok boys and girls,
with some help from Graham Newton for correct english, this news will
explain how to add an error indicating LED to your DAT.
The LED lights when an unrecoverable error occurs, that is, an error
that you can hear with your ears. (Theoretically!) You really won't
hear a single error, but it is a good way to judge the tape quality.
On my tapes it lights 4 or 5 times on a 120 min tape. On a damaged
tape it lights constantly and you can hear the errors in the audio or
it mutes.
Inside the Sony DAT, look for an IC307 with the part number CXD2601.
This IC is used for error correction, A/D, D/A interface, modulation,
demodulation and subcode decoder. In my DTC57 it is on the bottom of
the PCB, and you have to do a lot of disassembly to turn the PCB at 90
degrees. (The Pioneer was easier)
Look for Pin 82 (ERRF).
The SONY manual discribes it:-
Signal output discriminating whether or not DADT has interpolated data
("H": interpolated data)
Solder a wire to this pin and you can assemble the PCB back to its
original position. (Pin 81 is a corner pin, so this makes locating it
much easier!)
Normally, pin 82 is connected together with Pin 81 (ERRI). Check this!
If this is the case in your dat also, it is much easier to solder the
wire on the little SMD pins. Then you don't have to worry about a
solder bridge shorting to something.
At this point you need to build a monostable flip/flop with a 0.5 - 1
second timing. This is needed because a single error is too short for
your eyes to see. I built mine with a CD4538 CMOS IC.
The following is written from memory, so test it before you connect it
to your DAT!
CD4538 (CMOS Retriggerable Monostable Multivibrator IC)
Rx something between 10k and 100k
Build this circuit and test it outside of your DAT. You need 5V to do
so. Every time pin 4 of the 4538 is pulled from Vss (- volts) to VDD
(+ volts) the LED should go on for a short time. Adjust the time to
your liking with the values of Rx and Cx. 10k and 1uF will be short
timing and 100k and 10uF will be long timing.
Connect your circuit to the CXD2601. Look around for 5V. (I took mine
from a 74HCxx series IC nearby on the main PC board.
Switch your Dat on. The LED will often flash when you load a new
tape or when you do a fast forward. (this produces some errors)
On normal play, it will flash only rarely. You may wait more than
10-20 minutes for one short flash. If not, think about some head
cleaning or a new head.
Look for a place you like for the LED. I used a very small LED in the
left upper corner of the front. It looks really good.
Last words: If you don't know how to solder a wire to SMD's or you
don't know what a monostable is, stay away from the insides of your
DAT! Please don't ask me dumb questions like 'What is a 4538'? If you
don't really understand this, you will probably kill your DAT!
DISCLAIMER: The author is not responsible for damage you may cause to
your equipment by doing this modification. Proceed at your own risk!
Subject: Error LED for DTC 57, 55, 77, 670, Pionier D500
Date: Mon, 15 Apr 1996 16:41:26 +1030 (???)
*********************************************
Adding an Error Indicating LED to Sony DATs
*********************************************
Olaf Kaluza ---- e-mail:
olaf@criseis.ruhr.de
The following text describes how to connect an error indicating LED to
Sony-DATs and possibly some other DATs. (This has been tested with my
own DTC57 and a Pioneer DAT)
WARNING:
This is not the easiest do-it-yourself project!
YOU MUST KNOW WHAT YOU ARE DOING! It is very easy to damage your DAT,
and THIS WILL VOID ANY WARRANTY YOU MAY HAVE!
Pin Connection
=================
1 Cx (-)
2 Cx (+) and one side of Rx. Other side goes to VDD (+ volts) 3
VDD (+ volts) 4 10k and that wire from CXD2601 5 VDD (+ volts)
6 Output 7 NC 8 Vss (- volts) 9 NC
10 NC
11 NC VDD (+ volts)
12 NC |
13 Vss (- volts) Led
14 NC |
15 NC |
16 VDD (+ volts) 390 Ohm
/
/
C
4538 Pin6 --- 10k ---- B 2N2222 or 2N4401 or BC547
E
\
\
Vss (- volts)
Cx something between 1uF and 10uF (play with this.)