[Guide] How to playback 8mm video tapes recorded in a misaligned camcorder

[Marvolo]

Since I'm dealing with this very problem at the moment, I thought I'd share my experiences at this point. May they be helpful for others having the same issues with their 8mm video tapes.

Technical background:

Misaligned recordings are not an uncommon problem, they can occur with almost any tape-based formats, but especially with 8mm-based formats such as Video8 / Hi8 / Digital8. Compared to larger formats such as (S)VHS(C), Betacam, etc., this is probably due to the more compact and portable design of 8mm devices such as video camcorders or portable players, which due to their portability can be exposed to far greater stresses / vibrations than a stationary (S)VHS(C) device.

The path that a video tape takes through a playback device must be very precisely matched to the respective specifications of the corresponding format on the one hand, and to the respective playback device on the other in order to achieve the best possible results. Every tape-guided playback device has so-called tape guides (see Fig. 1), which are height-adjustable by means of a small screw on their upper side and which have the purpose of adjusting the exact angle between the tape and the rotating head drum so that the video heads located on the rotating head drum can read the information on the tape at exactly the right angle.


[Attachment 77492 - Click to enlarge]
Fig. 1: Tape guides inside of a Sony EV-S900E (PAL)

With some 8mm camcorders from the 80s and 90s, it was known that their manufacturers did not screw these tape guides tightly enough or that they became looser over time. Contrary to the often erroneous opinion that 8mm devices, in comparison to an (S)VHS recorder, could not cause any tracking problems (technically speaking, 8mm systems do indeed adjust the tracking themselves based on the inserted tape and therefore do not have a manually adjustable tracking controller like (S)VHS machines), mechanical misalignment of the tape guides while recording a tape could still lead to tracking problems, but these are now much more difficult to rectify compared to (S)VHS recorders, precisely because of the lack of a manual tracking setting.

If a recording is made in a tape recorder (e.g. Video8 or Hi8 camcorder), which is usually portable and frequently exposed to vibrations / movements and in which the tape guides are not (or no longer) firmly screwed into the mechanism in accordance with the norm, the device consequently records an audio and video signal onto the tape that is no longer aligned in accordance with the video norm for a 8mm system and is therefore no longer in a correct angle to the head drum and the video heads (see Fig. 2).


[Attachment 77493 - Click to enlarge]
Fig. 2: When the tape is inserted, the tape guides move upwards together with the tape to place it around the rotating head drum. The correct angle between the tape and the head drum is crucial for obtaining a clear signal.

In most cases, users do not even notice this problem, because the trick is that the respective camera still plays back its own "incorrectly" recorded tapes just fine as they were created by the same "faulty" camera. However, if that faulty camera dies over time and if years or decades later people want to save those valuable memories once created by a faulty camera, they are in for a rude awakening as the tapes cannot be played back with any other (correctly aligned) camcorder or playback device, or they will only do so producing major image or sound problems.

The aim now is to slowly and carefully adjust the tape guides using the screws on the top so that the angle between the tape and the head drum corresponds to the "correct" angle in which the tape was originally recorded in the misaligned camcorder. Of course, this process deliberately alters the manufacturer-specific standard / norm that the device or playback machine was distributed in and if you want to play back tapes that have been recorded in accordance with the standard, this former state must of course be restored afterwards. More on this later.

Procedure:

Basically any 8mm playback device can be adjusted in that way, as all these devices (logically) have these two tape guides. The only problem here is that with the many portable Digital8 camcorders (which can also play Hi8 & Video8) that you can buy on eBay or elsewhere for digitizing, it can be much more difficult to get free access to those tape guides without having to unscrew and dismantle 3/4 of the camera chassis. I first tried it with my Digital8 Sony camcorder, but as you can see, due to the design of this model, only one tape guide can be accessed without major disassembly. The second tape guide remains hidden behind the chassis. This depends largely on the Digital8 camcorder model. There are models where both tape guides are more easily accessible. This is usually the case with models that have the cassette compartment on the top and not on the bottom as with my model:


[Attachment 77494 - Click to enlarge]
Fig. 3: Poor access to the tape guides on a Sony Digital8 TRV 730E camcorder

To have better access to the tape guides, I therefore use the Sony EV-S9000E Hi8 standalone deck shown in the previous pictures above.

Step-by-Step guide:

Step 1: Remove the chassis of whatever player you are using as far as necessary so that the tape guides become freely accessible. This can be more difficult, especially with (Digital8) camcorders, depending on the model.

Step 2: Insert the tape so that the tape guides move upwards and the tape is being wound around the rotating head drum. Play the tape.

Step 3: Misalignments can manifest themselves in different ways: In my case, I got a good picture, however, sound was present only for a few seconds at a time. In contrast to VHS tapes, the sound on 8mm tapes is stored as audio frequency modulation (AFM) on an AFM track which, unlike VHS tapes, is not recorded on a narrow track at the very edge of the tape (as is the case with VHS), but is recorded in a helical way together with the video track. Therefore, the exact angle between the tape and the head drum plays a special role or else the sound may no longer be present or it might be crackling. Misalignments can also show in the form of white, horizontal noise / stripes at the top or bottom of the picture. These should not be confused, however, with the naturally occuring distortion at the bottom of the picture which is due to the heads turning. Every analog format has them and in the days of analog CRT TVs they were not seen because they lie in the so-called overscan area. On computer screens, the full image becomes visible, though.

Step 4: In order to turn the tape guides slowly and carefully, it is best to use a specially manufactured tool that is precisely matching the screws of the guides, such as this one (Tape Guide Post Tool). Unfortunately, these tools are very hard to come by - I've been searching for ages. If anyone here knows anything, I would be grateful for any tips. If you don't have such tools at hand, you can or must, like me, try a flat screwdriver, which can also be used to adjust the tape guides, it's just a bit more fiddly.

In any case: better safe than sorry. If you slip once and hit the rotating head drum, or even the head itself, the device may become a total write-off. Turn the tape guide carefully in one direction, e.g. clockwise, and observe the image.

At this point, it should be mentioned that for such adjustments, the image should best be displayed on an analog CRT-TV, not on a digital flat screen and certainly not as part of the final capture chain (with TBCs and other image enhancers on). For the adjustment, we want a live image that is as unadulterated as possible and CRTs are most reliable for fine adjustment.

Step 5: If you notice that going in one direction, the signal is not getting better or even worse, turn it in the other direction, millimeter / inch by millimeter / inch and observe the picture and sound. If picture interference tends to be at the upper part of the picture, the input tape guide (the left one) should be turned. If the interference is at the bottom of the picture, turn the right guide. In any case, both guides must be rotated in order to find out at which pivot point the best signal (picture and sound) is present. This involves a lot of trial and error, and in my case the range between the two end points where the signal becomes unusable is remarkably wide in both directions of rotation. In some cases, several 360° rotations are possible until I get from one end point to the other. The ideal does not necessarily have to be in the middle between the two end points.

The following video shows the steps mentioned above once again. The turning of the tape guides is only implied in the video, as I use both hands to turn them, but in the video I'm holding my cell phone with my left hand to film. You can see that, initially, I only get picture, but no sound, and there are also some white horizontal distortions at the bottom of the picture. After adjusting both tape guides, the white noise disappears and also the sound suddenly appears.

Step 6: Once the tapes have been successfully played back / digitized, the playback device can be restored to its original, standard state, depending on the intended use or requirements. Ideally, an 8 mm reference tape and an oscilloscope should be used to achieve best results. However, both can be comparatively expensive. The less purist alternative would be to record your own "reference tape" with exactly the same recorder before you carry out the adjustment and then align the tape guides in a way so that this tape can be played back again without any problems. However, this method is not technically accurate, but could be sufficient for "home use".

Here are some more visual guides:
https://www.youtube.com/watch?v=Li0PPZmVK1I&t=120s
https://www.youtube.com/watch?v=vuir89Ga5P4

[themaster1]

You have forgotten a key point, disable auto tracking before tweaking the guides posts. You want to be in "normal" mode otherwise you will most likely struggle against the machine for nothing

[johns0]

Also tighten the screws before playing the tapes.