My first Birch Model 700 and info on it's restoration

[Herderz]

After playing the new records on the cabinet machine I played one on my Birch model 700 portable that I have had for years. Although not as good of sound quality the volume was lower and it still ran pretty good.

I decided to restore this machine also, having not done anything to it after buying it years ago at a yard sale for $30 and getting some help from a talking machine friend and clock collector on setting the reproducer angle. This will be while waiting to come across a nice horn project. It has a stained canvass case with much wear over the years with leather handle which is in good shape.

It has a maple "I think" motor board, Card board or paper horn with the exit out the backside of the playing surface. All the hardware is there just needs a little detailed attention.

The motor is a General Industries Motor, with a 1 spring main drive. It has a casting number but I have no clue what it means, 19602? I looks in good shape but it has wear somewhere in the gear train. Just a little noisy compared to my rebuild of the Meisselbach motor on the cabinet. I am sure I will find it upon breakdown and cleaning.

I broke down the motor and cleaned everything up. It was not muk'd up as bad as the Meisselbach on my other machine. It still took some time to clean every gear tooth and inspect. The spring drum gear has slight wear or burring on the outside face but this is common on spring drives due to the gear having to be on one side of the spring or the other. This causes deflection of the gear mesh due to force trying to push the gear sideways (cocking) instead of a parallel mesh. I just take a small stone and knock the burr off the side of the gear. The fiber gear is in good shape and no noticeable wear at the top spindle bore with the shaft being held into the casting by a spring clip on the top side. These type clips are very hard to get off without tapping the spindle through the casting to remove, it is a pot medal casting and that can break. No problem with the main spring so I didn't crack open drum.

After polishing each gear shaft pinion ends and the bores and bushings I checked the clearances and everything looked good put the first gear off the drum drive gear. It had quite a bit of wear. You can see the gap between the pinion shaft of the gear and the bushing at the bottom, that is not a shadow, in the next pic. You can also see at the top the burring that has occurred over time. It is curling the brass out of the bore. This is a sign of poor lubrication over time.

The bore hole is oblong showing how the force of the train has pushed or wore the bore in the direction of the spring force.

After polishing the gear pinion on the lathe and measuring it at 4 mm. I needed to replace the worn bushing. I have many sizes of bushings being in the clock world so I needed a bushing with a 4.1 mm. bore and a 6.5 mm OD. I had a 4 mm. bore so I reamed it to 4.1 mm. with a broach and the 6.5 mm OD is a standard in the clock world also.

I removed the old bushing and pressed the replacement in. I assembled the gear back into the plates with only the spindle gear to check gear mesh and drag. It came out perfectly.

I reassembled the motor, oiled and greased it and wound it up and let it run down a couple of times. I think it will run smoothly now.

I started to clean the motor board, just a few scrapes but most will be under the platter. The surface rust has started to take over the plating on the hardware and will only clean up so much and will show it's age with missing final plating in spots.

I removed a couple pieces of hardware and the bowls but was not able to remove the speed scale, tonearm rest and needle lid mount. They are split riveted through the wood, so I cleaned the main board, hardware rust with a polish as best I could and reassembled the main board.

I think this might be a date stamp but am not sure. 81546 Could it be August 15, 1946?

Well it has taken me 2 weeks to get the next stage going. Have any of you ever flock'd. Well I have now and I am 60 years old! I finally got what I needed for the turntable and vent screen for the portable. Here is where I am at on the turn table, and I will let you see the result tomorrow after it dries.

[OrthoFan]

I used to own a Birch 700 and it's one of the few models I regret selling.

Sounds like you've done an excellent job with the mechanical components. The only thing I'd recommend is that the reproducer also be restored, if possible. Replacing the back (throat) coupler, and the rock hard rubber diaphragm gaskets with soft, fresh gaskets will greatly enhance the sound quality, and reduce surface noise and needle wear. These actually sound quite good once restored.

OrthoFan
PNG

[Herderz]

Thanks OrthoFan, Put I have had no luck finding these seals, The metallic diaphragm is in good shape put it has flat seals for the diaphragm and the back seal has hardened. Were do you go besides trying to make them for yourself?

[OrthoFan]

You might try posting a wanted ad in the Yankee Trader forum -- viewforum.php?f=9

Going back nearly 30 years when I owned the 700, I believe I found the throat coupling in a hardware store, trimming it to fit. As for the diaphragm gaskets, I think I carefully cut some flat rubber strips to serve as gaskets. (I don't think I used GE silicone calk on that sound box, but I may have. If that's the case, then I drew out a couple of thin beads of the calk, let them set completely, and used them as gaskets, filling in the gaps with fresh calk, as I gently positioned the diaphragm to fit in place.)

I DO recall that adjusting the needle bar pivot points took some experimentation with the settings to get them just right--allowing free movement of the needle bar without any noticeable "shake" or sideways movement of the coupling.

OrthoFan

[Herderz]

Thanks for the info OrthoFan, I am going to work on the reproducer and horn next.
Here is my flocking job on the turntable. It turned of good for a first timer at it.

[zapper]

Hi Herderz
You maybe interested in custom made gaskets from 0.5 or 1 mm thick material from Pedrofono, Spain. Check his website. He can make them to suit your size. I have bought several gaskets and diaphragms from him and they fit perfectly.
I live in the UK, but I am sure he will post to you, if you wish.
Good luck.

[OrthoFan]

Thanks for the info OrthoFan, I am going to work on the reproducer and horn next.
Here is my flocking job on the turntable. It turned of good for a first timer at it.

That is one beautiful job. It looks factory-original!

OrthoFan

[Herderz]

Well after the turntable flocking I next looked at the horn screen. It is very worn.

It is flocked too but this is different from a flat surface.

I broke down the horn to remove the screen and gasket.

The flocking is not so easy on screen, did the process but holes got clogged with adhesive and I had to use a tooth pick to polk the holes to open up the screen in places.

I set the screen on on top of the horn and I think it is not going to look that bad after re-assembly.

I pulled it all together after polishing the reproducer horn and putting it in the case.

I had to spin the machine up and play after the motor rebuild and the horn rejuvenation. It is sounding very good.

[Herderz]

I will have to tell you that I have been thinking of restoring the canvass case but it has it's own personality, I have got it restored mechanically with some cosmetically aspects to the inside and am thinking it is good enough for me at this point. But things can change.

[Curt A]

Re-covering the case is quite a project. I'm wondering if automotive upholstery/vinyl spray might work to rejuvenate the case...
Maybe something like this:
https://www.autozone.com/paint-and-body ... ?rrec=true