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Sony APR-5000

Sony APR speed experiments

We have been wondering just how far we can push the Sony APR-5000 capstan servo system, so we ran a few tests using an external oscillator feeding the reference port. Unlike Ampex, Otari, and Studer machines which use an external reference of 9,600 Hz; the Sony machines use an external reference of 19,200 Hz.

We found that the APR-5000s did not run reliably below 1.88 in/s — and that is achievable with a -50% varispeed already. It didn’t matter what the base speed was.

The APR-16 (cousin of the APR-24) did not run reliably below 3.75 in/s. But the good news was that we could bring 15 in/s down to 3.75 in/s using the external reference source. We were also able to run the APR-16 at 60 in/s, but takeup tension was a bit low.

Sony APR-5000 Hum Shields not working

I got a call today from a friend who said the hum shields on a friend’s APR-5003 were not working.

I recalled this had happened to one of my machines in the past.

Removing the cover surrounding the heads will expose the mechanism—of course the heads and pinch roller need to come off first.

Cleaning and lubricating the rods and other parts of the linkage should make all well again.

I used Zoom Spout Turbine Oil.

Sony APR-5000 head assembly problem

I was having slightly intermittent connections on one head assembly on a Sony APR-5000 and was concerned as to the cause because the 78-pin head connectors are essentially unobtanium and a headache to change.

As I installed and de-installed the head, I got to thinking that the connector might not be positioned correctly (i.e. perhaps the wrong hardware had somehow found its way into the connector mounting system.

When I measured the bottom (oriented as if the head were mounted in the machine) face of the connector mounting flange referenced to the bottom of the mounting posts (using a straight-edge across two of them), I discovered that, indeed, this connector was recessed about 25 mils (0.025″) further into the head assembly than several other ones. Adding a 25-mil thick washer should solve the problem.

This is posted in case you’re scratching your head with a similar problem. This is something I wouldn’t have immediately thought of. I don’t know if this was caused by aftermarket work or if it perhaps represents a manufacturing error.

Dangers of old tape recorders for playback; using the elevator head

We are currently working on some un-published tapes for a major Canadian folk artist. We have a 7.5 in/s 2-track stereo recording that was one of (if not the) first studio recording of this artist from circa 1972.

At some point, this tape was played on a 1/4-track machine that injected hum onto the left channel. Here’s what the magnetic viewer showed:

hum_overwrite_dsc_0571

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Playing a squealing reel of Sony PR-150 tape using D5 (Decamethylcyclopentasiloxane)

Today I worked on a batch of five Sony PR-150 7-inch reels recorded at 3.75 in/s in one direction, two-track mono. One of the five reels showed marked shedding during fast-wind/rewind (to get the original reel as takeup and to check the tape pack). Four of the five reels played fine. This one squealed horribly. I ran the tape up and back over the dispenser and then fixed it in position for running the tape over it during the playback session. Once again, D5, Decamethylcyclopentasiloxane, CAS Number 541-02-6 comes to the rescue. The lovely thing about D5 is that it evaporates.

APR-5003 with D5 dispenser

Is this better than cold playback? I don’t honestly know. Both work. This is easier if there is no reel machine standing by for cold playback (which there was not today). I keep a Nakamichi MR-1 in the refrigerator so it is ready to go when I need it. The Studer A810 I put in the fridge did not like it. The capstan motor seized up AND the heat output overwhelmed the refrigerator’s capacity to cool. I suspect the APR would also overwhelm the refrigerator’s capacity. Also, it is much easier to lubricate a reel than a cassette.