TEAC Z-7000 master cassette deck display problem
 

Hi,



My TEAC Z-7000 master cassette deck left channel level meter suddenly no
working. When cassette tape is playing, only right channel signal level
shows up on the display. Both channels sound appears normally on amplifier
without degradation. When the deck places in recording mode, the left
channel level does not display on either source and monitor mode, the
recording function work normally as it does. A shielded left and right
signals wire output from the playback amplifier board to the display board
which shows signal on an oscilloscope. From these reasons, I am suspecting
this problem causes by the display board itself.



The schematic diagram shows left and right channels signal go through a
NJM4558 dual op-amp first, and connected to NEC upc629c. After upc629C, few
digital ICs 4052 (1pc), 4081 (2pcs) and one LSI connected to the display. I
am thinking the LSI is the display driver and will not cause this problem
since the right channel signal can display normally. The problem may cause
by the op-amp or upc629c or digital ICs. I am wondering if anyone has work
on this cassette deck and has a similar problem which can share the ideas to
me. Also, if anyone has upc629C data sheet which can e-mail to me for
troubleshooting. Thanks for the information and I am very appreciate.



My e-mail address:



Thanks



Eric

TEAC Z-7000 master cassette deck display problem
 

On Mon, 12 Jun 2006 12:48:30 -0500, "Eric" put
finger to keyboard and composed:

My TEAC Z-7000 master cassette deck left channel level meter suddenly no
working. When cassette tape is playing, only right channel signal level
shows up on the display. Both channels sound appears normally on amplifier
without degradation. When the deck places in recording mode, the left
channel level does not display on either source and monitor mode, the
recording function work normally as it does. A shielded left and right
signals wire output from the playback amplifier board to the display board
which shows signal on an oscilloscope. From these reasons, I am suspecting
this problem causes by the display board itself.

The schematic diagram shows left and right channels signal go through a
NJM4558 dual op-amp first, and connected to NEC upc629c. After upc629C, few
digital ICs 4052 (1pc), 4081 (2pcs) and one LSI connected to the display. I
am thinking the LSI is the display driver and will not cause this problem
since the right channel signal can display normally. The problem may cause
by the op-amp or upc629c or digital ICs. I am wondering if anyone has work
on this cassette deck and has a similar problem which can share the ideas to
me. Also, if anyone has upc629C data sheet which can e-mail to me for
troubleshooting. Thanks for the information and I am very appreciate.

Interchange the L and R signals at various stages along the path until
you find the point at which the problem moves to the other channel.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.