The Talking Machine Forum — For All Antique Phonographs & Recordings

I swear I do know my way around a soundbox, but seems this week I've come across a couple that have made me scratch my head and pull out the two hairs I have left

I picked up that Sonat that has been lingering on the bay for a bit; someone had to adopt it!

Now, how does one open one of these? After taking the back off, there's an aluminium disc under it that won't budge. I assumed it's threaded in, but no amount of penetrating oil and unscrewing action would get it moving

It's a beautifully machined piece, and with the Algraphone connection (if I'm not mistaken) it should sound a treat.. if only I can open it

Any pointers would be very much appreciated

Probably a silly question but is there a hard-to-see grub screw somewhere around the periphery of the case ? Might the two stylus casting screws also be acting as disc retainers ?

emgcr wrote:Probably a silly question but is there a hard-to-see grub screw somewhere around the periphery of the case ? Might the two stylus casting screws also be acting as disc retainers ?

I thought that might be the case, but no grub screws to be seen and I removed the stylus assembly and it still won't budge. Plus, because how soft the aluminium disc is, I can't pry it open either. Not a very happy bunny at the moment, lol

How thick is the aluminium disc ?

Does the disc absolutely have to be removed? I'm guessing it pressed in. Show the other side of the reproducer please.

It's about 3-4mm thick I think

No way of accessing the gaskets from the front. Pictures attached

Try removing the diaphragm screw and then the two screws that hold the stylus bar to the body. The two screws might also hold the back in place.

chunnybh wrote:Try removing the diaphragm screw and then the two screws that hold the stylus bar to the body. The two screws might also hold the back in place.

I've tried that and no luck in afraid. I've got a feeling it may be pressed in, and only way to take out is to sacrifice the diaphragm and push it out from the front; not something I want to do

Yes, a tricky problem. I cannot help feeling that the aluminium disc might be screwed in as there would be no adjustment or guarantee of remaining in position if pressed in. Pressing, to me, would not suggest a good design. Aluminium can be very prone to being awkward to remove after extended periods can't it ? If you have the workshop facility you could try making a spanner with three holes to engage with the three screws you have removed so that you are able to exert twisting pressure. If this were done in conjunction with gently heating the case and irrigating the aluminium with cold water (or ice) you may find some joy ? Otherwise the only option I can see is to machine out the aluminium disc and make another.

Sorry not to be more helpful.

It must be threaded put it back together and hold the back plate in a vice and try to unscrew holding the body it may help to file two tiny flats on the back plate before reassembling shouldn't be noticeable