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Содержание 80-8

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Страница 2: ...s amplifiers and many sophisticated electronic devices Everything contributes a part to the system of multichannel recording Because of what we have learned about multichannel recording systems in the past 8 years TEAC decided to concentrate on improving functions in the 80 8 that are strictly the province of the tape recorder and to remove features that we felt were best placed elsewhere in the s...

Страница 3: ...ration Actual stopping point of tape will depend on transport speed when counter triggers the stop operation LED Record Status Indicators FUNCTION SELECT These lights show three states Light off Safe playback or input Light blinks Record ready but not in progress Light stays lit Recording in progress or RECORD PAUSE Mode aFUNCTION SELECT Buttons 8 Determine record and play status Up Safe playback ...

Страница 4: ...ueing Use only enough pressure to hear the signal Too much signal will damage the electronics so be sure the cue lever is nOt engaged locked when in fast motion The latch position is provided only for hand winding the tape to find an edit point Push the lever al1 the way up a second time to release input Level Control 8 For adjusting the source of line level signal Settinghas no effect on playback...

Страница 5: ...howing al1 parts tape path and al1 adjustments Screw for guides and head adjustments Hex ocket tvpe screws 0 h a r e for azimuth adjustment Fig 2 Head Location and Adjustment ERASE HEAD NORM RECORDIREPRODUCE HEAD MONITOR REPRODUCE HEAD TAPE GUIDESAND HEIGHT ADJUSTMENT HEX SOCKET SCREWS TAPE LIFTERS SCRAPE FLUTTER ROLLER NORM HEAD AZIMUTH ADJUSTMENT HEX SOCKET SCREWS MONITOR HEAD AZIMUTH ADJUSTMENT...

Страница 6: ...cord Read the manual decide what test equipment you can afford although it is not violently expensive it is not free and determine what service you can do yourself Cleaning The first thing you will need for service is definitely the least expensive Cleaning fluids and swabs The whole outfit 2 fluids and al1 the cotton swabs you ll need for months cost less than one roll of high quality tape We can...

Страница 7: ...n for quite some time Even if it does drift as a recorder it won t ruin previously recorded material and getting it back in good shape will not be too difficult To make electronic adjustments you need test gear so let s go over what s necessary 1 Alignment Tapes You need one for each speed that the recorder operates at For the 80 8 the specs are Reference fluxivity 250 nWb m Equalization standard ...

Страница 8: ...ape improvements in head design and the lowering of electronic circuit costs have made bizarre solutions quickly change into practical realities The optimums have shifted and will probably continue to do so Standards are set by man not cast in stone But while the scientists are boxing in the conference room we would like to be recording so TEAC has selected the IEC standard for recordlreproduce EQ...

Страница 9: ...must use NAB EQ tapes these amounts of read ing are correct NAB has more boost in playback the tape will read progressively higher as frequencies rise when played on an IEC adjusted recorder At 250 nWb m reference read these numbers to set IEC EQ Since the low frequency EQ on the 80 8 is fixed the differences are academic On to the next piece of test equipment 2 VTVM or FET Multimeter Fig 16 Head ...

Страница 10: ...ps in the heads that do the erasing recording and playing back must be precisely perpendicular to the tape PRECISELY Even a tiny error in alignment will rnake problems for the recorder If the heads are not in alignment both with the tape and with respect to each other tones recorded on one head will not play properly on the other In the table below the error is shown with the loss in dB for 1K and...

Страница 11: ...If you work up to 15K checking and adjusting a s you go you will avoid this mistake 0 OWi y 0 001 I O z z x s W r 001 1 o l IO 20 5 0 1 0 0 200 500 li 21 5 k O k 20k FREQUENCY IN HERTZ Fig 2 0 Velocity of recording media versus recorded wavelength in inchesfor e given frequency Once you have everything set up the reference tape is playing the scope is running and showing the X y display you need a...

Страница 12: ...R I FUNCTION I 13104 10kOhms I MONIT LEVEL 1 2 1 R103 10k I NORM LEVEL 1 l 3 l R105 22k l METER CAL l 1 R102 6 8k 1 MONIT EQ 1 5 6 7 8 9 10 I p 12 I R106 22k I PEAK LED 1 R101 6 8k R107 22k R111 lk R112 50k l l NORM EQ INPUT MONIT LEVEL ERASE BIAS LEVEL BIAS LEVEL R110 10k R108 3 3k REC LEVEL REC EQ PEAK ADJ 11 R109 470 REPRO BIAS TRAP L I REPRO BIAS TRAP L3 T 2 RECORD BIAS TRAP INTER STAGE TRANSF...

Страница 13: ...uld read O VU If it does not then you must use the extender card to gain access to the proper contro1 pot Carefully re move channel 1 electronics from the machine But don t unplug the cables that are attached to it There is just enough wire on them to allow you to attach the card extender see ill to the electronic card and re place the whole works in their proper receptacle The card will now opera...

Страница 14: ...st of the time you will make a reading and not have to adjust anything When some thing does go wrong you will be able to fix it very quickly and get back to recording In summary with the VTVM and test tape you have adjusted the playback level on the 80 8 to the test tape But your playback reference is not yet complete You have only zeroed one point on a line of frequency response To establish the ...

Страница 15: ...illator and its related circuitry The Bias Oscillator produces a very high frequency signal that does two big jobs in the80 8 It supplies the 100 kHz one hundred thousand cycles per second frequency to the Bias Amplifiers in the 80 8 There is a Bias Amplifier on every card one for each track The Bias Amplifier provides power for the erase head and bias signal for the record head Erasure is easy to...

Страница 16: ...ustment that they have you should get a reading of 65dB If the reading is is not very good at filtering a much different frequen higher than that you need more erase current Adjust cy If the master bias oscillator drifts it must be trim pot 7 R111 1 kOhms to correct the reading to re adjusted to produce 100 kHz Since this bias oscilla 65 dB This circuit does not require daily or weekly tor master ...

Страница 17: ...ave moved the input level pot on the front panel of the 80 8 to keep your reading on scale the next adjustment will correct your input reference Fig 27 Bias Level Adjustment Squencr I BIAS Pot rotated clockwise 1 307 Fig 28 Bias Limits Chart If there is insufficient C W rotation of trim pot 8 to achieve a peak dealer service of the Bias amplifieri oscillator system will be required Many voltages i...

Страница 18: ...oise is heard signals tapes as an absolute reference of magnetic level don t erase completely even after adjustment or there 5 Applied a reference level to the input of the 80 8 is not enough rotation of the bias trim pot left to get a and adjusted the O VU point to be 316 volt both drop in bias the whole adjustment should be in the circuit and on the meter considered but only under these unusual ...

Страница 19: ...he box The transport logic contro1and switching system are described in the service manual We ll sell you a copy if you want one but digital i c theory is very complex and the necessary test equipment for repairs costs more than the recorder The service manual is not written as a guide to the beginner so be advised it may not help your understanding of the 80 8 It is usefulonly to the experiencedm...

Страница 20: ...u have an old one you don t need Suspect any large change in adjustment that happens al1 at once Stop and think if you turn a pot and get no change in reading have you adjusted the wrong control Always turn the machine off when installing the extender card Remove the alignment tape from the heads when switch ing power on or off A switching transient on a badly adjusted recorder can print on the ta...

Страница 21: ...tion depress FUNCTION SELECT buttons 1 thru 4 The LED in dicators will blink signaling ready to record on these tracks Enter RECORD with the transport controls and the LEDs will remain lit At the same time the red LEDs on the DX 8 are lit indicating encode processing on these channels Also the DX 8 automatically sends the input signal to the output terminals Thus the signal going to the tape is en...

Страница 22: ...gs a little easier t0 may interpret this hiss as higher arder harmonics of the understand we ll ask you to use your imagination Imagine four little recording engineers in the box with recorded frequencies Thus recordings made with noise reduction may not sound as bright in comparison with their hands on a volume contro1each They are incredibly recordings made without noise reduction But a careful ...

Страница 23: ...cltape reproduce DOWN is source There are 3 ways to enter record 1 With the OUTPUT select in the NORMAL position depress the FUNCTION SELECT buttons for those tracks on which you wish to record The blinking LEDs will indicate ready to recordon those particular tracks Enter record with the TRANSPORT CONTROLS depress RECORD LED will light and PAUSE to gether Then push PLAY and al1 of the FUNCTION SE...

Страница 24: ...transport is locked in the RECORD mode It s not necessary to enter STOP to stop recording This is called punch and roll and is sometimes very useful Again it is risky because you run the risk of waiting too long to punch out Be careful SPECIFICATIONS TAPE WIDTH FORMAT REEL SIZE TAPE SPEED LINE INPUT LINE OUTPUT RECORD LEVEL CALIBRATION SPEED ACCURACY WOW and FLUTTER STARTING TIME FAST WIND TIME OV...

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