What's this quirk with the auto-brake on my Credenza?

[Cody K]

Here's something that's been bugging me for some time: One particular record (Boyd Senter's Doin' You Good, Victor 21912) sometimes, somehow, seems to set off the auto-brake on my Credenza about two-thirds of the way through. This doesn't happen with other records, nor does it always happen with the one above. The record is in E- condition, with nary a visual indication of any flaw that would possibly jostle the brake near the area where this happens. I've adjusted the brake to the best of my ability, checked its springs and so on, and, as I've said, 99.9% of records don't trip the brake before the record ends. Just this particular one, and only sometimes. What's going on here? Coincidence? Haunted record? Any ideas?

Thanks...

Cody

[brianu]

I have a few records with center holes that are no longer perfectly round and, when played on machines with very sensitive auto-stops, they'll trigger them part way through the song. Because they end up, once they start spinning, not perfectly centered on the turntable due to the issue with the center hole, as those discs spin, they cause the tonearm to horizontally move back and forth a bit more than normal, which triggers the stop. I'm sure there could be other causes as well though.

[barnettrp21122]

If you haven't already, you might try removing the entire brake assembly from the motorboard for a closer inspection of the trip-action on it. I was having the same trouble, and was able to more clearly see that slightly bending
the locking tongue engaged the brake more firmly, yet it tripped smartly when expected. These brakes shouldn't be so touchy as to not handle most off-center records, in my opinion. Good luck!
Bob

[De Soto Frank]

My first suspicion would be that the record in question has some lateral run-out ( eccentricity ), that is causing just enough back & forth oscillation in the taper-tube to cause the brake to trip.


What causes the Orthophonic brake to trip is the reverse-motion of the taper-tube ( supposed to occur from the eccentric groove in the center "run-out" area ).

You can pull the taper-tube all the way in to the center, and the brake won't trip, so long as there is no back-motion.

The arm does have to travel about half-way across the record before the brake-ratchet engages the rack-gear, so this why it wouldn't happen earlier in the record.

So, it might be a "haunted record"... haunted by lateral run-out. Check the spindle-hole, sometimes these get "hogged" and elliptical.

[welshfield]

Maybe the phonograph has the good taste to refuse to play Boyd Senter's Doin' You Good

Just a thought. They do seem to have a mind of their own.

John

[Orchorsol]

I find a surprisingly large proportion of 78s are "swingers", i.e. pressed off-centre.

[De Soto Frank]

Maybe the phonograph has the good taste to refuse to play Boyd Senter's Doin' You Good

Just a thought. They do seem to have a mind of their own.

John

Good thing it isn't a changer-machine - might fling it across the room !

[De Soto Frank]

I find a surprisingly large proportion of 78s are "swingers", i.e. pressed off-centre.

This example has some "swing" to it...

https://www.youtube.com/watch?v=doaqVHe9PTA


Enough, I think, to trip a sensitive auto-brake.

[Cody K]

Thanks, gents. The record-hole is perfectly round and not any more worn than many other records I have, BUT, based on your suggestions, I gave it a spin again to see if maybe the pressing itself is off-center. It is -- by something probably close to a sixteenth of an inch. I'd never noticed it. Not quite enough to be audible in play, but I'm guessing it's the cause of the problem. Add to that the very tiny bit of wiggle-room the hole might provide, and I guess it's enough to trip the brake. Bob, I did make that adjustment a while back, based on a suggestion (maybe it was yours?) in another thread about a different brake problem, so thank you for that.

John! I know Senter's one of those love-'im-or-hate-'im guys, but how could you be so unkind to such a snappy tune? It's hardly the most annoying Senter record, and I freely acknowledge that, yeah, there are a few.

Here's somebody else's vid of it on YT, in case anyone wants to hear it: https://www.youtube.com/watch?v=doaqVHe9PTA

On preview: Orchorsol, bingo!

And on non-preview: Oops, I see Frank's already linked to that vid. (And what whas that crack about flinging it across the room?!)

My thanks to all...
Cody K., Defender of the Senter