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: snipped-for-privacy@motorola.com
Thanks
Eric