Help with Sealing Credenza

[JOHNNYTREMPs]

I've read pretty much every post here about resealing the horn and tonearm, but a lot of it is going over my head. I don't know all the terminology used. Are there any tutorial videos out there? Or an original Victor service manual that explains it? I really just need pictures/videos because I'm a visual learner. Any advice is welcome!

[smitharthur]

Try to see if Brett Hurt, The Dyslexic Genius on YouTube, has any info on his channel. He is great to subscribe to, regardless!

[OrthoFan]

If you haven't seen it, this article is worth a read: https://www.gracyk.com/credenza.shtml

As for how to videos, I haven't seen any step-by-step instructions that show all aspects of the horn sealing process, but there are a few that show some specific types of repair/maintenance. For instance:

https://www.youtube.com/watch?v=F8q5fw3CmaU
https://www.youtube.com/user/HD7100/sea ... y=Credenza

For the most part, it involves ensuring that there are no air leaks in the horn chamber where parts come together, such as at the base of the tonearm, where the tonearm joins the cast-iron elbow (I think it's called an elbow), where the cast-iron elbow is connected to the back of the horn, etc. Inside the horn, you should check for seam gaps where wood is joined to wood, such as the lats that comprise the "heart," (central portion of the horn) and at the sides of the horn, etc. When I sealed my 4-40 horn, which is identical in shape to the Credenza horn, but much smaller (about 60 inches in length, including the tonearm), I worked white glue into the seams at the corners inside the horn, and worked silicone calk into the area where the cast iron elbow was joined to the back of the horn.

The arrows indicate where to check for leaks and apply sealant if necessary:

HTH,
OrthoFan

[JOHNNYTREMPs]

If you haven't seen it, this article is worth a read: https://www.gracyk.com/credenza.shtml

As for how to videos, I haven't seen any step-by-step instructions that show all aspects of the horn sealing process, but there are a few that show some specific types of repair/maintenance. For instance:

https://www.youtube.com/watch?v=F8q5fw3CmaU
https://www.youtube.com/user/HD7100/sea ... y=Credenza

For the most part, it involves ensuring that there are no air leaks in the horn chamber where parts come together, such as at the base of the tonearm, where the tonearm joins the cast-iron elbow (I think it's called an elbow), where the cast-iron elbow is connected to the back of the horn, etc. Inside the horn, you should check for seam gaps where wood is joined to wood, such as the lats that comprise the "heart," (central portion of the horn) and at the sides of the horn, etc. When I sealed my 4-40 horn, which is identical in shape to the Credenza horn, but much smaller (about 60 inches in length, including the tonearm), I worked white glue into the seams at the corners inside the horn, and worked silicone calk into the area where the cast iron elbow was joined to the back of the horn.

The arrows indicate where to check for leaks and apply sealant if necessary:

Credenza Horn.jpg

HTH,
OrthoFan

The pictures are fantastic! Thank you! Is there anything to seal on top of the unit or the front behind the screen?

[OrthoFan]

The pictures are fantastic! Thank you! Is there anything to seal on top of the unit or the front behind the screen?

After the motor-board is removed, you can inspect the top--outer portion of the horn--for cracks, warpage, etc.. If you have a spring motor, it will probably be covered with grease, so you might want to clean it with a grease solvent.

Right behind the screen or grille is the mouth (or front) of the horn, itself, as shown in the photo. No sealant is used between the grille and horn.

About the only other places where there can be air leaks is where the soundbox (reproducer) attaches to the tonearm, at the tonearm "crook", and at the base of the tonearm. You can use a little grease or Vaseline to coat the end of the tonearm before affixing the soundbox. Some collectors, myself included, wrap a few turns of plumber's Teflon tape around the end of the tonearm before inserting the soundbox.

For the crook, (that's the joint where you flip over the front of the tonearm), you can remove the lock-screw on the bottom, and then unscrew the coupling. Once removed, clean it and apply a light coating of grease to the threads and screw back in place. Not too tight, though. The sound box must be able to rise and fall without restriction.

I'm not sure what type of tonearm support back bracket you have. There were two styles, and the sealing instructions are different for each one. The earlier one without the overhang support, simply involved removing the bracket and coating the felt washer under it with fresh grease. I've never taken apart the later version, so I don't know if there is a washer positioned under it or not.

OrthoFan

[JOHNNYTREMPs]

The pictures are fantastic! Thank you! Is there anything to seal on top of the unit or the front behind the screen?

After the motor-board is removed, you can inspect the top--outer portion of the horn--for cracks, warpage, etc.. If you have a spring motor, it will probably be covered with grease, so you might want to clean it with a grease solvent.

Right behind the screen or grille is the mouth (or front) of the horn, itself, as shown in the photo. No sealant is used between the grille and horn.

About the only other places where there can be air leaks is where the soundbox (reproducer) attaches to the tonearm, at the tonearm "crook", and at the base of the tonearm. You can use a little grease or Vaseline to coat the end of the tonearm before affixing the soundbox. Some collectors, myself included, wrap a few turns of plumber's Teflon tape around the end of the tonearm before inserting the soundbox.

For the crook, (that's the joint where you flip over the front of the tonearm), you can remove the lock-screw on the bottom, and then unscrew the coupling. Once removed, clean it and apply a light coating of grease to the threads and screw back in place. Not too tight, though. The sound box must be able to rise and fall without restriction.

I'm not sure what type of tonearm support back bracket you have. There were two styles, and the sealing instructions are different for each one. The earlier one without the overhang support, simply involved removing the bracket and coating the felt washer under it with fresh grease. I've never taken apart the later version, so I don't know if there is a washer positioned under it or not.

OrthoFan

I've got the electric version.

What kind of grease should I be using? For sealing the non moving parts, could I use something like flex-seal? I also got tung oil to coat the horn after reading the recommendations of several people here.

The way you said "sealing instructions" makes it sound like there's an actual manual, which would make sense. Any idea where I could find that?

[OrthoFan]

What kind of grease should I be using? For sealing the non moving parts, could I use something like flex-seal? I also got tung oil to coat the horn after reading the recommendations of several people here.
The way you said "sealing instructions" makes it sound like there's an actual manual, which would make sense. Any idea where I could find that?

There's no manual I know of that provides step-by-step instructions specifically about sealing or making an Orthophonic tone chamber airtight. There is an excellent (general purpose type) service manual that contains step-by-step instructions for a variety of maintenance tasks relevant to all types of phonographs and gramophones: "The Compleat Talking Machine" by Eric Reiss. (Though the book is now out of print, a few copies turn up from time to time. In fact, there's a copy for sale here: http://www.antiqueradio4.com/Merchant2/ ... Code=Phono ) I don't have a copy, so I don't know if it has any tips about the Orthophonic tone chamber.

As for grease, I used a medium-weight grease. Probably, any modern-type grease would work, as long as it doesn't degrade over time.

OrthoFan

[MarkELynch]

Victor was a large organization with substantial dealer support.
I just posted Victor Service Bulletin No. 9 which contains full instructions for sealing the Orthophonic Tone Arm.

viewtopic.php?f=7&t=49635

Also, every collector should own a copy of Robert Baumbach’s book “Look for the Dog”, it contains several Victor service bulletins and has supplemental instructions for sealing the Orthophonic Tone Chamber.

Mark

[CharliePhono]

Also, every collector should own a copy of Robert Baumbach’s book “Look for the Dog”, it contains several Victor service bulletins and has supplemental instructions for sealing the Orthophonic Tone Chamber.

Mark

Mark, do you know the latest edition of the book, i.e., the latest printing? I haven't owned a copy since probably the first one and am not aware of the most up-to-date version.

Thanks!

[MarkELynch]

Charlie,

Wow, a lot has changed in Look For The Dog. The first (green) edition has early monochrome catalog cuts from the Victor catalog. The latest edition has actual color photos of every machine through 1929 except some special non catalog models. It look Bob many years to find and photograph so many machines. There is more historical and technical information as well. A must for all phonograph collectors! Buy it directly from the author:

http://www.mulhollandpress.com/styled-5 ... index.html

The companion book, The Victor Data Book is also worth buying.

http://www.mulhollandpress.com/styled-5 ... index.html


Many of the questions posted on this forum could be answered by referring to these two books! Go get ‘em!

Mark