Degradation and obsolescence comes in the smallest forms

When installing an audio lab with older equipment, ensuring that everything works can be more complex than it might first appear. This week, we are setting up capabilities to digitize 1/4″ open reel audio (as well as cassette) at the Institute of African Studies Archive. We were fortunate to start with two open reel decks: one that they had in house for some time, and one which had been donated by University of Ghana Professor Esi Sutherland-Addy for her current research project, “Shall I tell You or Shall I Not Tell You A Survey of Ghanaian Tales and Storytelling Tradition.”

revox_full

The open reel deck donated by Professor Sutherland-Addy is a Revox B77. This is a fantastic open reel deck but it is over 20 years old! Open reel decks, like all vintage audio equipment, have parts that degrade over time and require regular skilled maintenance. After cleaning the deck thoroughly we put up an MRL test tape to test the deck and were unable to get signal out of the left channel. Nat Kpogo and I got out the multimeter, the schematics for the deck and opened it up to see if we could identify the problem.

After tracing the signal path for continuity, swapping cables and ruling out the more obvious stuff they discovered that the small potentiometer (pot) used to calibrate the reproduction level for the left channel had a a very, very small but important piece that had broken off, potentially impacting signal flow. The image below is of the board that contains the reproduction electronics including the reproduction pots, which are the two disc shaped objects at the bottom of the image. You can see that the one on the left (which is for the right channel) is in tact and the one on the right (which is for the left channel) has a piece broken off.

potentiometers

Scratching our heads we realized that there were pots with the same specifications on the board containing the record electronics which we would not need for this deck. Problem solved! Nat busted out the soldering gun and pulled out the pots from the recording board to replace the broken repro pot. When we pulled the board out we discovered that three of the four pots on the board were also broken. Nat very carefully removed the one good pot and soldered it in place on the repro board. When we plugged everything back in and went to adjust the pot the very same piece broke off! This left us with no pots to use!

Revox is still around but they stopped manufacturing this deck in 1998 and no longer sell parts for the machine. It is possible to find a pot with the same specs, even if a different form factor; we could solder it in with jumper wires and piece together something that might work. Of course we weren’t sure whether this was actually the real problem or not. It’s possible we could replace the pot with a good one and still not have any left channel, resulting in a great deal of precious time lost. This led to a search of ebay where there was a board or two in Germany and the US. However, ordering these boards offered no guarantee that we wouldn’t run into the same degradation issue that caused the pots to break on our boards. We also found out that shipping and customs can be rather tricky and we had budget considerations as well. We decided to ponder what to do and to look into budget matters while moving forward and working with the other deck we have – a Tascam BR-20 deck which is working properly.

The BR-20 plays at speeds of 7.5 ips and 15 ips, while the B77 plays at tape speeds of 3.75 ips and 7.5 ips. There are many tapes in the collection that are 3.75 ips so the issue will need to be resolved in one way or another, although there are also many 7.5 ips tapes as well. In the interest of progress, we got underway with 7.5 ips tapes. Without having another working deck with the speed and head configuration we need we would be stopped in our tracks (an unpleasant scenario that Seth Paris and I confronted back in 2008 on a project working with the recordings of Kofi Ghanaba). So we will move forward with 1/2 track, 7.5 ips tapes while we figure out how to fund and procure the parts and equipment we need to get the B77 in good working shape (btw – we also need a 1.875 ips deck and 1/4 track heads at 1.875, 3.75 and 7.5 ips – donations are welcome!).

Among other lessons learned, it reminds us, as we find all too often in our work to preserve content stored on media that is degrading and obsolescing, that the degradation and obsolescence is holistic in every sense. It is about physical deterioration of the equipment and parts as much as it is about deterioration of the media. A loss of one equates to a loss of access to the content stored on the media. Obsolescence is not only about equipment, but the technology as a whole: the specific equipment, along with its parts, as well as the tools and accessories used for calibration and alignment; the expertise and knowledge of its operation, upkeep and maintenance; the community of manufacturers and users that surround it, and more. Being confronted with these scenarios is a firm reminder of the race against time that we’re facing, and brings into focus even more clearly the importance of the great work that Judith and her team at the Institute of African Studies Archive are doing to preserve their audiovisual collections –  Not later. Now.

Chris Lacinak

 

2 thoughts on “Degradation and obsolescence comes in the smallest forms

  1. Hi Chris,

    have you considered to replace the potentiometer with fixed resistors for the time being?

    Another option would be to solder a wire from the right connector of the broken pot to the middle contact (that would give you the same configuration as with the left pot – assuming that the setting for the left pot as seen in the image is ok).

    These two approaches would at least give you the opportunity to check if everything else is working.

    All the best,
    Georg

  2. Thanks for your reply Georg! Yes, your recommendations are indeed on-point and reasonable methods for continuing to troubleshoot the issue. We found ourselves in a race against time to get the machines up and running so we could get through setup and training in a small window of time. After our initial attempts fell short, with one working deck I decided that it was more important to keep momentum going. As you can imagine, there are lots of issues that pop up along the way and present challenges in these scenarios and it’s important to choose your battles and prioritize. Seth Paris continues doing training and practice for one more week with the team. After that, once operations are running more smoothly with the 7.5ips tapes Nat Kpogo will go back and revisit the issues with the B77 in preparation for the 3.75ips tapes.

    Thanks again for reading the blog and taking the time to share your expertise! It’s greatly appreciated!

    Chris

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