Tracking Issues: Repairing a VHS Deck

Editor’s Note (2021-04-06): The following post is the last in a series of three written by Savannah Campbell on the topic of analog video deck maintenance and repair. These posts were written by Savannah in the spring of 2017 as part of an Independent Study project with media conservator/audio engineer Bill Seery and video engineer Maurice Schecter, and published on NYU’s Web Publishing service under the blog title “Tracking Issues”. At an unspecified point sometime after Savannah graduated later that year, NYU cut off public access to the site. Though the content was recovered (with an assist from Ben Turkus) and the blog re-published, I’ve offered to also host the posts here on The Patch Bay. For the whole series, also check out  “Swab the Decks!” and “Repairing a U-Matic Deck”! Thanks, Savannah!


For this video deck repair project, I worked on a Panasonic NV-8950 VHS player.

This particular model of VHS player is pretty special. It is the only VHS player ever manufactured to have dynamic head tracking. Dynamic head tracking enables the viewer to see a clear image when operating a tape deck in shuttle or jog mode, or when viewing a single image. To achieve this image stability, one of the video heads must be able to move/bend slightly to pick up a stable image. This feature was usually included on broadcast and professional-quality decks, and not on consumer-grade models. Thus, VHS players, as the format was designed primarily for consumers, largely did not include dynamic heads. As such, when operating a VHS player in shuttle/jog mode, there is a static/snow effect bleeding and blurring throughout the image, and the image does not appear stabilized. The dynamic head tracking feature thus makes the Panasonic NV-8950 unique among VHS players, and if a working deck of this model can be found, it would be preferable for use in a digitization station.

When I first hooked up this deck and ran a test tape through it, I almost immediately noticed a problem. I was running the deck with the lid removed so I could see the tape moving through the deck as it played. I quickly noticed the tape bunching up near where it should have been spooled back onto the take-up reel. Instead, the tape was bunching up inside the deck. I had to quickly stop the tape, remove it from the deck, and manually wind the tape back onto its hub inside the VHS cassette.

Upon closer inspection, it appeared the take-up reel was malfunctioning. It was either not turning at all, or turning far to slowly to wind the tape onto the reel. As I examined this deck towards the end of a day, I left a note on the machine stating the problem, the date, and my initials.

When I next returned to work on the deck, I was able to take a closer look at it and determine what the issue was. I took off the lid again and began to examine the inside of the deck. One of the nice things about the Panasonic NV-8950, and several other VTR models, is that the screws are color-coded. Red screws are consumer screws. They are the ones to remove first when taking apart the deck. You can see the red screws in the images below. They held the tape elevator in place. I had to remove the elevator in order to take a closer look at the take-up reel.

One of the most apparent problems was that the inside of the deck was very dirty: a black goop was smeared throughout the inside of the deck, including in the area near the malfunctioning take-up reel. In the images below, note the black goop inside the deck. It can must obviously be seen covering the circuit board between the reels.

Where was all that black goop coming from? Taking a look at the white plastic reel in the center of the image, notice that it has a black rubber band around it. This is called the idler tire, and it helps drive the supply and take-up reels. The idler tire in this deck was badly deteriorating. The rubber on it was eroding away, creating thick black goop that was smearing all over the inside of the machine. In the above picture, also take note of the thin medal band surrounding the supply reel (the black hub on the left side). That medal band is part of the braking mechanism, and the felt brake pad on it has almost completely fallen off. That too needed to be replaced.

For this project, the first thing I did was remove the bad idler tire. Then, I thoroughly cleaned up the goopy black mess with acetone on PEC Pads and Q-tips. Acetone is a powerful solvent, and quickly cleaned up all of the melted rubber remnants.

After cleaning the deck, I replaced the idler tire with a new one, and installed it into the machine. Then, I took care of the brake pad issue. I took off the old, fraying felt (which was easy to do since the old glue had mostly worn away already). Then, I measured out and cut a fresh piece of felt and attached it to the metal brake band using contact cement.

Here is what the inside of the deck looked like after I made these repairs. Note the clean circuit board, new idler tire, and new brake band.

With this work done, I re-installed the cassette elevator, hooked up the deck to monitor again and played a test tape. This time, the deck functioned beautifully, transmitting great video and audio signals to the monitor.

The last step I took was leaving a note on the machine, documenting the repairs performed.


Savannah Campbell (M.A. in Moving Image Archiving and Preservation from NYU, 2017), is now a Media Preservation Specialist, Video & Digital Media at the Whitney Museum of American Art in New York City. Prior to coming on board as part of the Whitney’s Media Preservation Initiative, she was a Fellow in Magnetic Media Preservation at The Standby Program and worked on audiovisual projects for the Dance Heritage Coalition, CUNY TV, and Crawford Media Services.

Tracking Issues: Repairing a U-Matic Deck

Editor’s Note (2021-04-06): The following post is the second in a series of three written by Savannah Campbell on the topic of analog video deck maintenance and repair. These posts were written by Savannah in the spring of 2017 as part of an Independent Study project with media conservator/audio engineer Bill Seery and video engineer Maurice Schecter, and published on NYU’s Web Publishing service under the blog title “Tracking Issues”. At an unspecified point sometime after Savannah graduated later that year, NYU cut off public access to the site. Though the content was recovered (with an assist from Ben Turkus) and the blog re-published, I’ve offered to also host the posts here on The Patch Bay. For the whole series, also check out  “Swab the Decks!” and “Repairing a VHS Deck”! Thanks, Savannah!


For my first video deck repair project, I examined a Sony BVU-950 U-Matic machine. This deck was purchased at an auction and had been untested at the time I first looked at it.

Since this machine was completely untested, the first step I took was to plug it in, hook it up to a monitor, pop in a test tape and see what happened. The deck powered on and images from the test tape (color bars in this case) soon could be seen on the monitor. However, the tape was squeaking terribly and drop out was appearing intermittently, but at regular intervals. Another issue I noticed fairly quickly was that one of the fans was not functioning at all.

The first order of business was troubleshooting the problem of the squeaking tape and determining what the cause was. As this may have been an issue with the test tape itself (possible sticky-shed syndrome, with the binder layer from the tape flaking off), I first got another test tape to use. I also unscrewed the lid from the machine and cleaned all parts of the tape path with PEC pads and isopropyl alcohol. For more pervasive messes where debris was stuck onto metal posts and even the video heads, I used acetone to clean them completely (acetone is a much stronger solvent than isopropyl alcohol). After cleaning the deck, I put in test tape #2 to see what happened. The squeaking issue persisted. With the lid of the deck removed, I watched the tape run through the machine. I noticed that when the deck squeaked, it was also putting creases in the tape at regular intervals. It was a good thing I was using a test tape and not a tape from an archival collection!

One method for diagnosing issues involves running the U-Matic deck in “emergency mode.” In emergency mode, the deck will thread up the tape path WITHOUT the presence of an actual tape in the machine. This feature is only available on some deck models (including the BVU-950), and it is one way to examine all of the moving parts of the machine, such as the capstan, to make sure they are functioning. To run the machine in emergency mode, it is necessary to disconnect the tape elevator (as pictured above).

Side note: When undergoing a repair project, it is highly recommended to have the service manual on hand! By following the instructions in the BVU-950 service manual, I was able to run the deck in emergency mode and assess the condition of the machine.

After running the deck in emergency mode, all of the parts seemed to be functioning properly. With guidance from video engineer Maurice Schechter, we determined the problem was likely with either the capstan or the pinchroller. As the capstan was spinning normally when we ran the machine in emergency mode, we decided to take a closed look at the pinchroller.

I removed the pinchroller and took a closer look at it. The material on it looked work out and glossy. As seen in the picture above, the pinchroller looked very smooth and slick, not rubbery like it should be. Even worse, the pinchroller had developed a beveled pit towards the bottom of it. This is the culprit of the tape creases! The worn out pinchroller was pushing the tape upwards, causing the creases in it. Luckily, there were spare pinchrollers on hand and I was able to simply swap out the part right away. With a new pinchroller in place, the deck was no longer creasing the tapes.

Though the primary issue with the BVU-950 was resolved, I still had more to learn, and more tests to run.

Though the test tape was no longer being creased, it still seemed to be moving fairly sluggishly throughout the deck. The part of the machine responsible for spooling the tape back onto its take-up reel was not moving very quickly (the left of the two black hubs in the picture above). I removed the take up hub from its metal post and greased up the post to make it smooth and slick. When I removed the hub, I was able to get a better view of the brake system, and noticed that the brake pads were very worn out and smearing black debris everywhere. I removed the worn out brake mechanism (also pictured above) and replaced it with a new one. After this, the tape ran smoothly through the U-Matic deck.

Next up, I took a closer look at the video heads themselves. To do this, I used a tool called a Tentel Head Protrusion and Eccentricity Gauge. This tool can be used for measuring how far the video heads protrude from the drum, which can tell you how worn out the heads are and if it is time to replace them. It can also be used to make sure the video heads are aligned and properly positioned in the drum.

First, I attached the tool to the drum and gently spun the drum around to measure the video heads. The guide book the tool comes with includes a chart with the recommended length of a healthy video head (which changes depending on which video format one is working with. It will be different for U-Matic, VHS, etc.). The heads on this particular machine were below the recommended length, so Maurice and I decided to change the heads.

Placing the new heads in the correct position was by far the most tedious part of this repair process. To ensure the heads were aligned correctly, I again had to use the Tentel gauge. To align the heads, I had to gently (GENTLY) and repeatedly tap the drum until the heads were resting in the correct position. The sensitive video heads must be within 5 micrometers of the ideal alignment point in order to pick up the signal correctly. It was very easy to tap the head just a little too much and move it off target. This process required lots of time and patience, but I eventually got the new heads aligned properly and screwed them into position. Once in position, I used the Tentel gauge to measure the protrusion of the new heads and wrote down their length.

To document this repair and leave notes for future engineers, I made a note of the drum itself with sharpie. I mentioned that the heads were replaced and noted the T/P (tip protrusion) of the V (video) and E (erase) heads, as well as the total number of hours on the drum. I also noted the date and left my initials.

To perform one last, thorough cleaning of the deck before I closed it up, I took an air hose and blew out all of the dust inside of it, leaving it as pristine as possible.

Throughout this process, I did not forget the issue of the malfunctioning fan I noticed when I first tested out the machine. When I plugged it back in again to test the new heads, one of the machine’s two fan units was not moving at all, and the other fan was moving very sluggishly.

To remedy this problem, I removed both of the fan units and replaced them with brand new ones. Fans for video decks can easily be found online (as similar fans are used in all sorts of electronics, including computers). To select the proper fan, one just needs to note the size and voltage of the fan already in a video deck, and purchase a replacement of the correct size and voltage.

With the new fans in place and the deck in otherwise good working order, I was finally able to screw the lid back on the BVU-950 and call my first major video deck repair project complete.


For the next post in the “Tracking Issues” series, continue to “Repairing a VHS Deck”.

Savannah Campbell (M.A. in Moving Image Archiving and Preservation from NYU, 2017), is now a Media Preservation Specialist, Video & Digital Media at the Whitney Museum of American Art in New York City. Prior to coming on board as part of the Whitney’s Media Preservation Initiative, she was a Fellow in Magnetic Media Preservation at The Standby Program and worked on audiovisual projects for the Dance Heritage Coalition, CUNY TV, and Crawford Media Services.

Tracking Issues: Swab the Decks!

Editor’s Note (2021-04-06): The following post is the first in a series of three written by Savannah Campbell on the topic of analog video deck maintenance and repair. These posts were written by Savannah in the spring of 2017 as part of an Independent Study project with media conservator/audio engineer Bill Seery and video engineer Maurice Schecter, and published on NYU’s Web Publishing service under the blog title “Tracking Issues”. At an unspecified point sometime after Savannah graduated later that year, NYU cut off public access to the site. Though the content was recovered (with an assist from Ben Turkus) and the blog re-published, I’ve offered to also host the posts here on The Patch Bay. For the whole series, also check out “Repairing a U-matic Deck” and “Repairing a VHS Deck”! Thanks, Savannah!


When encountering a video deck that is not playing back a signal properly, one of the first steps of troubleshooting problems is to examine the deck (especially the video heads) for signs of dirt and other debris. Running old tapes tapes through a deck can cause them to shed particulates onto the machine’s tape path, clog the heads, and prevent the deck from being able to read subsequent tapes. Additionally, some parts of a video deck are made of rubber, which can degrade over time. Old rubber can turn into black goo that can smear throughout the deck. In other areas of the machine, glue holding mechanical parts together can melt and also wreak havoc. All sorts of goop and debris can hinder how a VTR plays back tapes, impeding a tape’s journey throughout the deck or clogging the heads so the machine cannot interpret a tape’s video signal.

There are many cleaning solutions and materials available for cleaning video decks. In this post, I will discuss several different kinds of cleaning supplies and their effectiveness at scrubbing various deck components clean.

Cleaning Solvents:

Isopropyl Alcohol

The mildest, gentlest cleaning solution recommended for cleaning video heads is isopropyl alcohol. Isopropyl alcohol is safe to use on almost all parts of a video deck (metal, plastic, circuit boards, etc.), which is why many in the archival profession will recommend it as the best and safest option for cleaning VTRs, especially the sensitive playback heads. It is best suited for use on machines that will be regularly cleaned and are currently used for playback/digitization. Isopropyl alcohol is good for minor clean-up tasks, such as wiping dust particles and minor debris that was left behind from a tape with sticky-shed syndrome. If using isopropyl alcohol, one should purchase a solution with as little concentration as possible. 90% isopropyl or higher is recommended.

 

Xylene

Moving from mildest to most severe cleaning solutions, xylene is the next-strongest solvent after isopropyl alcohol. Xylene is effective at cleaning up more pervasive remnants of gunk/debris, especially on the metal parts of the machine. Be careful about using xylene on plastic components, as it could melt them, and never use it on any rubber components at all as it will dry them out.

 

Acetone

The strongest solvent recommended for cleaning VTRs is acetone. Acetone is absolutely the most effective solution for removing gunk, goop, glue, and debris. Though acetone is a very powerful solvent, it can still be safely used to clean anything metal, as well as circuit boards. It is even safe to use on the video heads themselves, especially if they are particularly clogged with goop. Acetone should never be used on plastic or rubber because it is strong enough that it will melt these materials. However, for the dirtiest of the dirty decks out there that have not been opened up or cleaned in years, acetone will get the job done.

 

Cleaning materials:

Q-Tips

Q-Tips are great for cleaning any hard-to-reach nooks and crannies in the machine. For cleaning video decks, the Q-Tips with long handles are well-suited for the task. Though some cleaning swabs can leave fibers behind in the deck, the less-fluffy varieties of Q-Tips are a good option for deck cleaning and are less likely to shed in the machine. Q-Tips are best-suited for cleaning metal posts and hard-to-reach mechanical parts. Do not clean the video heads themselves with Q-Tips.

 

PEC Pads:

PEC Pad wipes are well-suited for cleaning decks, especially video heads and other easy-to-reach parts of the tape path. Anywhere the tape itself touches can be cleaned with a PEC Pad. PEC Pads are also recommended to use because the cloth does not leave any fibers/lint behind. If you use a cheaper, flimsier type of wipe (like KimTech wipes or tissues), they will shed all over the machine and create another mess to clean up. PEC pads are both sturdy and soft, and can be used safely on any part of the deck. To clean a video head, the best practice is to hold a PEC Pad doused with alcohol completely still against the drum/heads, and rotate the drum underneath it, making sure to apply sufficient pressure with the pad.

Newspaper

For audiovisual archivists or video engineers that finds themselves without PEC pads or Q-Tips, a page from the day’s newspaper is a surprisingly effective option for cleaning a video deck. Newspaper is completely safe to use on the deck with any type of solvent. Ink will not get on the deck, and the paper itself will not leave any fibers behind. Newspaper is sturdy, yet gentle enough to be a reliable and affordable option for cleaning a deck. Just tear off a piece, douse it in your favorite cleaning solution, and wipe the deck clean! If print newspaper is not available, sturdy paper like from a legal pad can work in a pinch, though printer paper is not stable enough for the task (it will leave fibers behind).


For the next post in the “Tracking Issues” series, continue to “Repairing a U-Matic Deck”.

Savannah Campbell (M.A. in Moving Image Archiving and Preservation from NYU, 2017), is now a Media Preservation Specialist, Video & Digital Media at the Whitney Museum of American Art in New York City. Prior to coming on board as part of the Whitney’s Media Preservation Initiative, she was a Fellow in Magnetic Media Preservation at The Standby Program and worked on audiovisual projects for the Dance Heritage Coalition, CUNY TV, and Crawford Media Services.