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 Post subject: 5A rebuild questions
PostPosted: Tue Aug 27, 2019 8:55 am 
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Victor II
Martin - 16 y/o
Joined: Mon May 07, 2018 6:27 pm
Posts: 438
I'm rebuilding a 5a reproducer and have some questions. For one, the back panel is stuck to the body, and I obviously dont want it to break, what is the best way to seperate them safely? I'm assuming its stuck because it has expanded.

The ball bearings also need replacing, where could I find good replacements?

Would rubber orthophonic gaskets work well with the 5a?

Thanks
Martin


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 Post subject: Re: 5A rebuild questions
PostPosted: Tue Aug 27, 2019 2:09 pm 
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Victor IV
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Joined: Sun Feb 15, 2009 5:40 pm
Posts: 1587
Location: Holy Loch in Argyll and Bute
You need to carefully prize the bezel off the backplate. That's easier said than done. There is only one sure fire way of doing it but it involves damaging the diaphragm so you would need to have spare handy.

No, the rubber gasket is wrong. Also, what ballbearings? The 5A doesn't have any?


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 Post subject: Re: 5A rebuild questions
PostPosted: Tue Aug 27, 2019 2:24 pm 
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Victor III
Joined: Sun May 27, 2012 2:38 pm
Posts: 753
Location: United Kingdom
You could try tapping a craft knife blade gently round the join between the body and the backplate, but you need to go very slowly, and twisting the blade gently as you go. If you get the two parts seperated, (and there's no guarantee you will without breaking it), then you will see that the backplate has a raised disc in it. The edge needs to be filed down until the backplate locates into the front easily.

I presume you need one of the ball bearings in the stylus bar sockets?


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 Post subject: Re: 5A rebuild questions
PostPosted: Tue Aug 27, 2019 3:26 pm 
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Victor IV
Joined: Sat Jul 09, 2016 7:12 pm
Posts: 1533
Steve wrote:
Also, what ballbearings? The 5A doesn't have any?


Didn't the 5a/5b use the same needle bar pivot as the HMV/Victor #4? (I know the 5a I had did.)

There was a tiny, single, ball bearing situated on each side, as per this illustration:

Attachment:
Capture.JPG
Capture.JPG [ 47.08 KiB | Viewed 286 times ]


I don't think they'd need to be replaced, though.

OrthoFan


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 Post subject: Re: 5A rebuild questions
PostPosted: Tue Aug 27, 2019 3:52 pm 
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Victor II
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Keep'em well oiled
Joined: Mon Dec 18, 2017 2:51 am
Posts: 387
Location: Madrid, Spain
I once lost one of the balls, and as I didn't have at hand one that would fit, I installed two balls instead of one, much smaller in size, but the two tiny balls filled adequately the space, and the soundbox could assembled and works fine! It is a 5A I assembled together using old spare parts from other 5A/B soundboxes. The diaphragm was full of holes and wrinkles, but I could carefully clean it and carry into shape, sealing the holes with white vinyl glue (Elmer's glue) and in the end, it works fine, although it lacks some treble.
Inigo


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 Post subject: Re: 5A rebuild questions
PostPosted: Wed Aug 28, 2019 5:07 am 
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Victor III
Joined: Sun May 27, 2012 2:38 pm
Posts: 753
Location: United Kingdom
OrthoFan wrote:
Steve wrote:
Also, what ballbearings? The 5A doesn't have any?


Didn't the 5a/5b use the same needle bar pivot as the HMV/Victor #4? (I know the 5a I had did.)


I don't think they'd need to be replaced, though.

OrthoFan


Yes, the 5a used the same ball bearings as the Victor No.4, and I agree that there isn't any need to replace them (unless one has got lost?)


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 Post subject: Re: 5A rebuild questions
PostPosted: Wed Aug 28, 2019 8:40 am 
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Victor II
Martin - 16 y/o
Joined: Mon May 07, 2018 6:27 pm
Posts: 438
Thanks for the responses guys, I've been busy lately, now I can keep up with the thread. When I dissasmbled the reproducer, a bearing was already missing (or I'm clumbsy). I think the person who tried to restore the hmv wanted to clean and oil the bearings and lost one. I'm mainly assuming it's gone because the pivot goes all the way into the fulcrum bar.

I've tried the exacto knife method without success. I obviously would prefer not to sacrifice the diaphragm, but if I really cant get it separated it might be my only option.

Thanks
Martin


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 Post subject: Re: 5A rebuild questions
PostPosted: Wed Aug 28, 2019 10:18 am 
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Victor IV
Joined: Sat Jul 09, 2016 7:12 pm
Posts: 1533
Mormon S wrote:
I've tried the exacto knife method without success. I obviously would prefer not to sacrifice the diaphragm, but if I really cant get it separated it might be my only option.

Thanks
Martin


If the back plate is still firmly in place, and the diaphragm is in good condition--no major dents, punctures, or tears--you might want to consider leaving it in place.

As has been noted, unlike Victor, the Gramophone Co. used FELT gaskets, which normally do not deteriorate. Their sole purpose is to isolate the diaphragm from the casing, and hold the ridge of the diaphragm firmly in place. (The corrugated section is responsible for the diaphragm's flexing ability.) To ensure that the felt gaskets are airtight, a few collectors I've know have suggested putting a few drops of oil around the rim to saturate the felt gaskets, but I'm not sure this is really necessary.

OrthoFan


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 Post subject: Re: 5A rebuild questions
PostPosted: Wed Aug 28, 2019 10:31 am 
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Victor IV
Joined: Mon May 13, 2013 2:04 pm
Posts: 1670
Exacto knife ? Heck no ! You need to use a meat carving knife , seriously , and tap around as you go with a hammer , thin craft Knives and scalpels aren't strong enough , also if the back is seriously bowed don't try it


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 Post subject: Re: 5A rebuild questions
PostPosted: Wed Aug 28, 2019 11:47 am 
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Victor II
User avatar
Keep'em well oiled
Joined: Mon Dec 18, 2017 2:51 am
Posts: 387
Location: Madrid, Spain
I've used one drastic (not absolutely) method in two cases of plate jamming. Basically it consists in choosing a point in the front ring, between two screws, cut away carefully the ring with a rotary tool (Dremel) this freeing the pressure. In the process it is unavoidable to cut also a section of the backplate outer rim, which protrudes from the front ring.
After this is done, you can disassemble the soundbox. This process, if carefully done, will not touch the diaphragm.
Later, the front ring is installed again on the backplate, adding a piece of paper in between just under the cut. Then the cut is refilled with epoxy, and the paper piece avoids the epoxy from getting stuck to the backplate.
The point most comfortable for cutting the ring is between ten and eleven o'clock, looking the soundbox from the front, needle down at six o'clock. This point is between two screws, and far from the needlebar fulcrum area.
There is a black point, though, and it is that this repair reshapes the front ring adapting it to the swelled backplate. No problem for them both, but when installing the soundbox front cover, you will notice that it doesn't fit well; the distance between its screws has not swelled, as for the backplate and the cutaway front ring. This small misadjust is not a major problem, for the cover is full of holes and very flexible, but you will notice a certain force is needed to screw it in place.
Another interesting point when reassembling these soundboxes is the installation of the backplate. I will cite my own explanation in the fourth post of topic
viewtopic.php?f=7&t=39943&p=237233&hilit=Relaxed+position#p237233
There I explain the technique for installing the backplate in a relaxed position and sealing the airleaks with vinyl glue.
Inigo


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