Schlagwort-Archive: vhs

Panasonic AG-6400 VHS-Portable

Panasonic AG6400

A new member of the collection of old multimedia devices is the Panasonic AG-6400. The AG-6400 is a (semi) professional video recorder from the 80s. The device records on VHS magnetic tapes and also reproduces this standard. It is portable and was the recorder for the video cameras of that time. It draws its energy from 12V NP1 batteries and can provide approx. 27W for the camera connected to it. That was about the power requirement of a 3-tube camera.

This device, too, had gotten some traces of time that largely restricted its function. Simply said – it was broken. This defect manifested itself in a stuck capstan shaft . At first I thought the shaft was ’seized‘ due to corrosion, but the reason was completely different. Interestingly, a ball bearing had been pressed out of its press fit, so that the flywheel attached to the shaft touched the bobbin of the capstan motor. The magnets in the flywheel held it in place. This error could be easily and quickly remedied by pushing back the ball bearing and then fixing it.

the videorecorder without housuing
pcb folded out to service position
view to the mechanics (drumhead)

After the mechanical fault was repaired and a first function test, a fault in the 5V power supply was still to be found on the power board. This was expressed by a failure to start all drives. Here, an IC fuse was defective in the switching converter. This was triggered by a defective Schottky diode in the buck converter circuit. This bug was also quickly solved. And after checking and adjusting the operating voltages according to the setpoints in the service manual, the drive did its job again. I was even amazed at the excellent image quality that the device could reproduce. Due to its compact dimensions, I can even use the AG6400 to digitize old VHS tapes in the future.

Elaborate wiring between the boards

 

frontview

In the data sheets and advertising for the AG-6400, the manufacturer has advertised some features and functions as follows:

High quality image reproduction

The tape speed corresponds to the VHS standard with a video track width of 49µm. Several technologies for clear and detailed image reproduction are combined in the device.

HI-FI Sound
A four-channel system consisting of two ’normal‘ audio channels with Dolby noise reduction and two ‚HD-Sound‘ channels allow you to enjoy high quality recordings. A 3.5mm headphone jack and two 6.3mm microphone jacks for separate feeding of both channels, including separate control with VU meters, complete the range of audio options.

VU-meter and audio level controls

Time Code record and playback
For control in linear editing systems, the recorder enables the recording of external EBU timecode signals on channel 2 of the longitudinal track.

External camersocket

A connection for an external camera with a maximum power consumption of up to 27W is also available. Cameras with 3-tube Vidicon system can be connected here.

A diagram with the connection options is shown in the following picture:

Anschlußschema de AG6400 (Bild: Herstellermanual)

Technische Daten:

Manufacturer National/Panasonic  Central Osaka Japan
Year ca. 1988
System VHS Portable Videorecorder
Powersupply DC 10.5 to 16V
Powerconsumtion 14Watt, (with camera ca. 41W)
Videosystem Fourhead  rotationsystem (helical scanning)
Luminanz FM azimuth recording
Farbsignal subcarrier phaseshift Recording
Video SNR 43dB
Audiosystem Normal und HD-Audio
Normalaudio 1  fixed audiohead
HD-Audio 2  rotating heads , 1 earasehead
Stereoton Normalstereo (2Kanäle über Längsspur )
  HD-Stereo (2Kanäle über Schrägspur)
TV-System CCIR (625 Zeilen, 50Halbbilder) PAL Colour
tape speed 23.39mm/s
rewind time(180min tape) 4.5min
size 222x90x270mm
weight 3.0kg (without battery)
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from Video8 to Digital

 

Now, during the holidays, it is a bit of time to copy the time stored on magnetic tape image and sound to new media.

The video recordings of the early 90s were still analogue on 8mm tapes instead. No, not Super8 (that was the movieformat like in cinema those times but much smaller), but on Video8 or HI8 (the better quality variant – comparable to VHS and SVHS, where the „HI“ or the „S-“ technically by a separate recording of the Y – and C- signal was realized (Y = luminance, so brightness information and C = chrominance, ie color information) .The recording itself, took place on magnetic tape in helical-scan technology (as well as VHS, U-Matic, Betamax, BetaCam, Video2000…). Except that the tape just has a width of 8mm and not 1/2 „or 1 inch, as with other systems. Also the sound is recorded in the helical scan.

In order to get the old records into a digital format that is common today, you need the following four things.
First, the tape (cassette) with the probably exciting content of days gone by. Next, a player is needed.

Here I got myself a then professional HI8 recorder, with which the playback of the tapes should work. The recorder is called EV-S9000E from Sony and came back to the net after almost twenty years break. After a short while, the smell of putrid fish was noticeable. An indication that some electrolytic capacitors of the SMD design are no longer in order. (A well-known problem with devices of older age and elko’s smaller, more compact design.) Nevertheless, I left the recorder on the net and made myself smart, which functions failed because of the numerous, not value-accurate components. So the power supply started and delivers at least. The flourescence indicator has failed. The 60V anode voltage seems to be missing here, no matter the tape drive works, so bring the analog signal to the computer.
 
 
For this I got myself a video to USB converter of elgato. Quickly installed the necessary software and inserted the first tape and pressed „Play“. The picture, however, was a disaster. All lines were totally distorted and offset. (As if the line frequency was wrong). So, before I put everything together again and disappear with the recorder in the workshop, I have again seen in the Config menu of the recorder. There I switched all AUTO options to manual, the television standard on PAL geknüppig and last but not least the TBC (TimeBaseCorrector) off. Lo and behold, the TBC is over too. Actually he should generate an absolutely stable time signal for the video line, but with defective electrics this is no longer possible.
Since I do not have ten tapes to digitize, the recorder should hold out …
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