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 Post subject: HMV number 5A sound box. The little balls inside the needleb
PostPosted: Sat Mar 17, 2018 9:42 am 
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Victor O
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Joined: Mon Dec 18, 2017 2:51 am
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Location: Madrid, Spain
I'm repairing a HMV 5A sound box. The needlebar is missing one of the little balls at one side of the support. I have a replacement needlebar from one of those Indian copies of the soundbox, but I don't know how to extract one of the balls to replace it in the other needlebar. Any kind soul can help me? How can I extract the balls from the replacement bar? Is there any place where I can get these balls? Maybe a good replacement for the whole needlebar with the balls inside? Thanks to you colleagues.
Inigo


Last edited by Inigo on Sun Mar 18, 2018 5:35 pm, edited 1 time in total.

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 Post subject: Re: HMV number 5A sound box. The little balls inside the nee
PostPosted: Sat Mar 17, 2018 11:08 am 
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Victor O
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I am one of Those Men That Keep Everything they can take out from any apparatus which is going to the trash. That philosophy of life has got for me a box full of everything, bites from any conceivable machine. In my miraculous box I have found a little capstan from an old video player that seems to have inside a little ball bearing, which I'm dismantling to see if the balls inside serve for the purpose. Will report later...
Inigo


Last edited by Inigo on Sun Mar 18, 2018 5:36 pm, edited 1 time in total.

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 Post subject: Re: HMV number 5A sound box. The little balls inside the nee
PostPosted: Sat Mar 17, 2018 2:27 pm 
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Victor O
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Me, myself, alone... Finally I've managed to get the tiny balls out of the bearing. There were 6 balls, but so small that I had to put two of them inside the needle bar bearing. But in the end, it worked. Now the soundbox is assembled and ready to test. It is badly broken, because it is one of those with the pot metal back which has swelled, and the neck is also broken. So I've had to fix it with black electrical tape. The rubber neck is also completely hardened. I have substituted it using two strips of natural rubber, forming a ring (actually two, one inside another) that fits in the tonearm and in the sound box neck. The diaphragm is the worst part of it. It is so full of tears and holes...! I cleaned it completely with alcohol and solvent, using a small paintbrush and a cotton earstick. I removed the spider, and put the legs straight with the aid of small needlenose pliers. Then I also put the diaphragm straight, very carefully, using the rounded back of a thin paint brush, and later filled all the holes and tears with white plastic glue. I found that these glue is capable of covering holes, putting a tiny drop on each one. When it dries it leaves only a transparent plastic film covering the hole. At least I've tested the soundbox, and it is well airtight. I also cut out the tiny nails of the spider legs that grasp the diaphragm. After putting everything straight, I fixed the spider to the diaphragm using the same white plastic glue. Of course, I set the spider on a new position, between the former holes.
The needle bar end was another nightmare, as it had lost the two protrusions that go into the spider ring. I welded two new legs from a tiny copper U-shaped strip. I managed to put everything in place, and the sound box is ready for testing. Will report later...
Inigo


Last edited by Inigo on Sun Mar 18, 2018 5:43 pm, edited 1 time in total.

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 Post subject: Re: HMV number 5A sound box. The little balls inside the nee
PostPosted: Sat Mar 17, 2018 2:52 pm 
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Victor O
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Joined: Mon Dec 18, 2017 2:51 am
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Location: Madrid, Spain
I'm excited because I've finally learned after 25 years playing with gramophones how to adjust precisely the needle bar in the orthophonic HMV sound boxes. I recently repaired my golden 5A soundbox in the big HMV194 reentrant gramophone. And the sound is very beautiful.. that soundbox gave me lots of work... But it has a good fresh 5B diaphragm. The soundbox body, though, is somewhat cracked, but using that marvelous white plastic glue I managed to put it completely airtight. I did also something I've noticed improves greatly the sound, which is to relax the pressure on the diaphragm border, loosening the back screws until just the point where the soundbox is airtight, but no more. Then I fix the screws with a half-turn, and using again that white plastic glue I seal them in place. As there is a gap left between the sound box and it's back, due to the pressure relaxation, it is also filled and sealed with the same plastic glue. Using that, you get an airtight soundbox, with a full, warm sound...
Inigo


Last edited by Inigo on Sun Mar 18, 2018 5:46 pm, edited 1 time in total.

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 Post subject: Re: HMV number 5A sound box. The little balls inside the nee
PostPosted: Sat Mar 17, 2018 3:12 pm 
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Victor Jr
Joined: Tue Mar 06, 2018 3:42 pm
Posts: 10
Inigo wrote:
Me, myself, alone... Finally I've managed to get the tiny balls out of the bearing. They wear 6 balls, so small, that I have to put two of them inside the needle bar bearing. But in the end it worked. Now the soundbox is assembled and ready to test. It is badly broken, because it is one of those with the put metal back which has swelled and the neck is broken. So I had to fix it with black electrical tape. The rubber neck is completely hardened. I have substituted it with two strips of natural rubber forming a ring that fits in the tonearm and in the sound box neck. The diaphragm is the best part of it. It is so full of tears and holes...! I cleaned it completely with alcohol and solvent. I removed the spider, and put it right with the aid of small needle-nose pliers. Then I put the diaphragm straight very carefully, using the rounded back of a thin paint brush, and fixed all the holes and tears with white plastic glue. I found that these glue is capable of covering holes, putting a tiny drop on each one. When it dries only a transparent plastic cover is left on each hole. At least I've tested the soundbox and it is airtight. I cut off the tiny nails that were grasping the diaphragm, put everything straight, and fixed it to the diaphragm using the same white plastic glue. The needle bar end was another nightmare, as it had lost the two protrusions that go into the spider ring. I have welded two new legs from a tiny copper strip. I managed to put everything on place, and the sound box is ready for testing. Will report later...

So much to write, and not to provide not a single photo?


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 Post subject: Re: HMV number 5A sound box. The little balls inside the nee
PostPosted: Sat Mar 17, 2018 3:39 pm 
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Victor O
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Location: Madrid, Spain
A video of the test of the repaired 5a using my 102.

https://youtu.be/NLs17N_3CIM
Inigo


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 Post subject: Re: HMV number 5A sound box. The little balls inside the nee
PostPosted: Sat Mar 17, 2018 3:42 pm 
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Victor O
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Location: Madrid, Spain
Vlad71 wrote:
So much to write, and not to provide not a single photo?

Sorry... A defect i must correct... I didn't take a single photo of the process... When i do these works, I'm so excited and concentrated that i forgot to take photos step by step... I promise next time i will do...
Inigo


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 Post subject: Re: HMV number 5A sound box. The little balls inside the nee
PostPosted: Sat Mar 17, 2018 4:17 pm 
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Victor O
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Posts: 63
Location: Madrid, Spain
Attachment:
File comment: A general view of the repaired 5A. I removed the front grille for the repaired diaphragm to be displayed.
IMG_20180317_205444.jpg
IMG_20180317_205444.jpg [ 3.24 MiB | Viewed 408 times ]
Attachment:
File comment: Herein you can also see the left bush broken, glued again in place with liquid-metal epoxy compound.
IMG_20180317_205500.jpg
IMG_20180317_205500.jpg [ 2.71 MiB | Viewed 408 times ]
Inigo


Last edited by Inigo on Sun Mar 18, 2018 5:49 pm, edited 1 time in total.

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 Post subject: Re: HMV number 5A sound box. The little balls inside the nee
PostPosted: Sat Mar 17, 2018 4:34 pm 
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Victor O
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Keep'em well oiled
Joined: Mon Dec 18, 2017 2:51 am
Posts: 63
Location: Madrid, Spain
Attachment:
IMG_20180317_205403.jpg
IMG_20180317_205403.jpg [ 3.65 MiB | Viewed 406 times ]
Inigo


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 Post subject: Re: HMV number 5A sound box. The little balls inside the nee
PostPosted: Sat Mar 17, 2018 4:49 pm 
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Victor O
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Keep'em well oiled
Joined: Mon Dec 18, 2017 2:51 am
Posts: 63
Location: Madrid, Spain
Attachment:
IMG_20180317_205331.jpg
IMG_20180317_205331.jpg [ 2.85 MiB | Viewed 401 times ]
Attachment:
IMG_20180317_205337.jpg
IMG_20180317_205337.jpg [ 2.78 MiB | Viewed 401 times ]
Attachment:
IMG_20180317_205353.jpg
IMG_20180317_205353.jpg [ 3.63 MiB | Viewed 401 times ]
Inigo


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