Re-attaching needle bar to diaphragm HMV 5A

[bikesteve]

Hey folks, Has anyone had any luck re-attaching a needle bar to an aluminium diaphragm? Specifically an HMV 5A Soundbox that at some stage probably had a lid slam down on it.
-To me it looks like a case of clean old solder off, align it as best possible & attempt to solder back on but be interested to hear from someone who's attempted it..

HMV 5A.jpg (141.77 KiB) Viewed 1626 times

[gramophoneshane]

I reattached one once, but I didn't clean the old solder off, nor did I add any new solder. I simply allowed what was already there to reattach it. I used a toothpick to apply a minute amount of soldering fluid at the point of contact first, and once cooled I used a cotton bud dampened with water to rinse any excess soldering fluid away so it wouldn't corrode the aluminium.

[Inigo]

Me yes, always with a common electrical solder pen for circuitry, and the common greased stain wire roll, exactly as if I were soldering a wire to a terminal. Takes a bit of patience, but works.
Your spider grommet has still the old solder pegs; I'd try first to reshape or adjust the needlebar feet to be in contact with the old pegs, as were in their original position, and reuse the old pegs again. They are already soldered to the grommet.
I've cleaned old pegs, and it was enormously difficult to solder new pegs on the grommet, it takes time and it gets very hot!
Just introduce the feet into the grommet; if the fork is correctly separated, you actually need a bit of tiny force to put them into the grommet, and they'll stay in place just with that little pressure of the knife edges against the grommet. Bend them a bit forward or backwards so the knife edges fall where the old pegs are. Before soldering, adjust the penetration of the fork into the grommet so the needlebar is in the right angle. I mean: if the fork is too deeply or too shallow introduced, the needlebar will be scanted, and the needle will fall on the record not perpendicular.
Once the ideal location is found (trial and error, or you may be lucky and match it at the first trial) then you put the soldering pen in contact with one foot, it will heat and eventually the old stain peg will adhere to it, just like soldering a wire. Then the other foot, let it cool, et voilá.

[old country chemist]

Lay the soundbox on it's side, and press the forked end of the stylus bar well into the dimple in the diaphragm. Now add from a pointed rod 3 drops at least of PVA GLUE, Make sure the stylus bar is still embedded in the dimple part, and set aside for several hours in a warm area, or overnight. I have just done this with a 5a soundbox that had been repaired with red sealing wax. I cleaned off the wax, then added the PVA. Late I played a couple of records, they sounded just as good as my excellent 5a soundbox. It is a difficult job to solder the bar to the diaphragm, so that was my answer or "bodge"

[Inigo]

I've used largely the pva glue also, for small screw sealing, joint sealing, etc. in soundboxes.
But lately I've discovered, with dismay, that after a year or two it dries out too much, looses its small amount of elasticity, its adherence to metal, and starts to peel off at the smallest provocation!
Maybe my glue is of bad quality, or too old, who knows!

In the other hand, it's easy to apply, so I'll have to repeat it!

[bikesteve]

Many thanks for all your comments, I'll try the solder method and hopefully it'll take, I did try using Shane's method before just resting the iron on the old joint but maybe it wasn't getting hot enough as it just wasn't joining so was wondering if it was even solder originally.
I've used tiny drops of epoxy glue before to seal holes in older diaphragms with good success (still ok after a few years now).
I did think about temporarily placing a spacer between needle bar and soundbox housing whilst fixing it to get as near as perpendicular as possible.

[Inigo]

A good idea, tell us your progress on this...

[Steve]

A spot of epoxy glue. Job done.

[Inigo]

I would suggest that if you're going to use the glue, you should remove the old stain pegs first. They added mass at that point, which is not desirable. A drop of glue has the advantage of almost not adding mass. Then the treble will be more effectively transmitted. The sound will be more crispy and detailed...

[bikesteve]

I'm happy to report that after re-aligning the off centre needle bar & aided this time by some solder flux both parts joined solidly. -Sealed a couple of tiny holes on the spider with glue and it plays well. Thanks again!