Toshiba D-VR3SU, Service Manual

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Circuit Operating Descriptions
7-38
13) SW Noise Compensation
Unlike the linear audio,insted of using fixed head,drum heads are used,which creates halting points However,in order for
the audio to be headed continuously,the damages from halting points are modulated,which creates noise. SW noise
compensation is a block to minimize this particular noise.
14) Hold Pulse
It makes standard signal(Pulse) to compensate SW noise.
15) DET(Hi-Fi/LINEAR)
From the Hi-Fi envelope inputed from pre-amp,it decides whether the signal passing through L-CH BPF is Hi-Fi or
LINEAR tape it’s size(the signal passing through BPF is below 10mVpp, it is not Hi-Fi,therefore,it output linear)
16) DOC(Drop Out Compensation)
If demodulation is conducted without properly treating the damage on Hi-Fi envelope caused by scratch on the tape,noise
occurs. In order to improve this noise occurrence,DO DET compensate the drop-out using the same methode of
compensating the switching noise when the damage on the envelope ranges 10~15mVpp.
17) ENV DET
To obtain optimal tracking,envelop must be peak to peak and micom should be in DC. It is a function to convert Hi-Fi
envelop to DC. If it is lower than 0.8V at micom,it sends linear mode date to HiFi IC.
18) Serial Data Decoder
It receives IIC BUS to enable the operation of inner block and decodes into serial data.