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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

Repair of Crystal Phono Cartridges ?



 
 
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  #1  
Old November 5th 06, 03:51 AM posted to sci.electronics.repair
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Posts: 4
Default Repair of Crystal Phono Cartridges ?

A common problem on old phonographs with crystal cartridges seems to be that
the Rochelle salts crystal disintegrates with humidity. I'm working on one
of these phonos now. I have an idea how it might be repaired, but rather
than reinvent the wheel, I thought I would ask how others have attacked this
problem.

It seems to me that I might be able to use a ceramic piezo element like this
one

http://www.allelectronics.com/cgi-bi...EZO_DISC_.html

to replace the old crystal inside the phono cartridge. The size is just
about right. Has anyone tried this? If so, is the output level and frequency
response comparable to the original crystal?

Or is there a better approach (that doesn't cost more than an old phonograph
is worth)?

Thanks for your comments.


Ads
  #2  
Old November 5th 06, 04:17 AM posted to sci.electronics.repair
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Posts: 150
Default Repair of Crystal Phono Cartridges ?

"Blake" ) writes:
A common problem on old phonographs with crystal cartridges seems to be that
the Rochelle salts crystal disintegrates with humidity. I'm working on one
of these phonos now. I have an idea how it might be repaired, but rather
than reinvent the wheel, I thought I would ask how others have attacked this
problem.

I haven't a clue, but you should probably ask in rec.antiques.radio+phono
Because there would be people there trying to keep (and revive) older
equipment, and this is the sort of thing that gets discussed over there
(even if I'm not sure this specifically has been discussed).

Michael
  #3  
Old November 5th 06, 06:24 AM posted to sci.electronics.repair
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Posts: 420
Default Repair of Crystal Phono Cartridges ?

On Sat, 4 Nov 2006 18:51:42 -0800, "Blake"
wrote:

A common problem on old phonographs with crystal cartridges seems to be that
the Rochelle salts crystal disintegrates with humidity. I'm working on one
of these phonos now. I have an idea how it might be repaired, but rather
than reinvent the wheel, I thought I would ask how others have attacked this
problem.

It seems to me that I might be able to use a ceramic piezo element like this
one

http://www.allelectronics.com/cgi-bi...EZO_DISC_.html

to replace the old crystal inside the phono cartridge. The size is just
about right. Has anyone tried this? If so, is the output level and frequency
response comparable to the original crystal?

Or is there a better approach (that doesn't cost more than an old phonograph
is worth)?

Thanks for your comments.


It must be a pretty big cartridge if it will take a 15mm diameter
ceramic disc. In my experience, the crystal/ceramic element in a phono
is quite small so I think you are not going to have any success in
repairing it. The elastic suspension carrier for the element might
have deteriorated as well so you will probably find this a problem.

Not to put too fine a point on it, why not just buy a new ceramic
cartridge and save all the hassle? Though looking at some of the
prices here http://www.turntableneedles.com/brow...cts/Index.html
you might not like it.

You can get better prices here but the range is smaller
http://www.soundring.com.au/Cartridges.cfm
  #4  
Old November 5th 06, 04:40 PM posted to sci.electronics.repair
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Posts: 119
Default Repair of Crystal Phono Cartridges ?


Blake wrote:
A common problem on old phonographs with crystal cartridges seems to be that
the Rochelle salts crystal disintegrates with humidity. I'm working on one
of these phonos now. I have an idea how it might be repaired, but rather
than reinvent the wheel, I thought I would ask how others have attacked this
problem.

It seems to me that I might be able to use a ceramic piezo element like this
one

http://www.allelectronics.com/cgi-bi...EZO_DISC_.html

to replace the old crystal inside the phono cartridge. The size is just
about right. Has anyone tried this? If so, is the output level and frequency
response comparable to the original crystal?

Or is there a better approach (that doesn't cost more than an old phonograph
is worth)?

Thanks for your comments.



Andy comments:

Well, what is the worst that could happen if you spent a coupla bucks
on a ceramic element and it didn't work as well ?

I suspect that the next step would be to find the cost of a
compatible
replacement cartridge and decide if it is worth the extra money.....

Probly not..... Sometimes you have to spend a few bucks just to
find stuff out...

I would, personally, never consider repairing the inside of a phono
cartridge. It's too tiny. Throw some bucks at the problem. That's the
American way :))))) !!!

Andy in Texas

  #5  
Old November 5th 06, 05:08 PM posted to sci.electronics.repair
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Posts: 4
Default Repair of Crystal Phono Cartridges ?


"Ross Herbert" wrote in message
...
It must be a pretty big cartridge if it will take a 15mm diameter
ceramic disc. In my experience, the crystal/ceramic element in a phono
is quite small so I think you are not going to have any success in
repairing it. The elastic suspension carrier for the element might
have deteriorated as well so you will probably find this a problem.

Not to put too fine a point on it, why not just buy a new ceramic
cartridge and save all the hassle? Though looking at some of the
prices here http://www.turntableneedles.com/brow...cts/Index.html
you might not like it.



Thanks for the reply.

Actually, I've already examined the failed cartridge. The old crystal seems
to be a slab about 15mm long and 10mm wide, fitting into a space 15mm wide
and 25mm long inside the cartridge shell. I thought I might be able to grind
the sides of that circular 15mm barrium titanate piezo on a belt sander to
adjust the fit. Or if it shatters on grinding, find a slightly smaller one.

My old crystal was clamped into the cartridge by two rubber blocks, one
glued to the top shell and the other to the bottom. The gap between measures
about the same as the crystal thickness. Are these what you mean by the
elastic suspension carrier? There was also a thin, crumbly black coating on
the white crumbly crystal. I took this black coating for a conductive
electrode, but if this is an elastic suspension, then I might need to
understand its function better. Maybe the barrium titanite can go without a
coating. Or I could dip it in the kind of liquid rubber they sell for
coating tool handles. This point bears some more consideration.

As for buying a new cartridge, well . . . You guessed right about my
willingness to invest cash in the project. This phono isn't a fine antique,
and would probably not fetch more that $25 after I finish the repairs. But
more importantly, I wouldn't learn anything or have any fun by hiring a
specialist to do the job for me. And we're all in this for the fun of it,
aren't we?


  #6  
Old November 5th 06, 05:36 PM posted to sci.electronics.repair
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Posts: 4
Default Repair of Crystal Phono Cartridges ?


"Andy" wrote in message
ups.com...


Well, what is the worst that could happen if you spent a coupla bucks
on a ceramic element and it didn't work as well ?

I suspect that the next step would be to find the cost of a
compatible
replacement cartridge and decide if it is worth the extra money.....

Probly not..... Sometimes you have to spend a few bucks just to
find stuff out...

I would, personally, never consider repairing the inside of a phono
cartridge. It's too tiny. Throw some bucks at the problem. That's the
American way :))))) !!!

Andy in Texas


Thanks for the comments, Andy. Actually, the cartridge in this 1952 phono
I'm working on is luxuriously spacious. Overall, the cartridge is about 2"
long and 3/4" wide. I only had to drill out four rivets to open the shell.
The space for the crystal is over 1/2" wide and fully 1" long. This was
obviously made before the word "miniaturization" took root in the
electronics industry.

And I follow your logic completely. It will cost me a big 75c to try this
piezo see how it works. Compare that to $50 for a rebuilt cartridge, and you
can probably guess which I will try first.

But it never hurts to see what experiences others have had first. No point
in learning the same lessons over again.


  #7  
Old November 5th 06, 06:14 PM posted to sci.electronics.repair
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Posts: 25
Default Repair of Crystal Phono Cartridges ?


Blake wrote:


"Andy" wrote in message
ups.com...


Well, what is the worst that could happen if you spent a coupla
bucks
on a ceramic element and it didn't work as well ?

I suspect that the next step would be to find the cost of a
compatible
replacement cartridge and decide if it is worth the extra money.....

Probly not..... Sometimes you have to spend a few bucks just to
find stuff out...

I would, personally, never consider repairing the inside of a phono
cartridge. It's too tiny. Throw some bucks at the problem. That's
the
American way :))))) !!!

Andy in Texas


Thanks for the comments, Andy. Actually, the cartridge in this 1952
phono I'm working on is luxuriously spacious. Overall, the cartridge
is about 2" long and 3/4" wide. I only had to drill out four rivets to
open the shell. The space for the crystal is over 1/2" wide and fully
1" long. This was obviously made before the word "miniaturization"
took root in the electronics industry.

And I follow your logic completely. It will cost me a big 75c to try
this piezo see how it works. Compare that to $50 for a rebuilt
cartridge, and you can probably guess which I will try first.

But it never hurts to see what experiences others have had first. No
point in learning the same lessons over again.


Looking through my junk box I have a couple of old mono phonograph
shells ! Like yours the elements have long gone !

However both have a pair of screws, maybe 6ba thread and set 11/16th
inch apart that holds in the cartridge. On one these the screws are
tapped into the metal of the shell. On the other there is a Bakelite
pad, about 3/16th thick with two holes in it for the cartridge and a
tapped centre one that goes right through, with a matching hole in the
top of the shell.

Maybe you could do something along these lines with yours and fit a
cheap Xtal cartridge insert ?

--
Baron:
  #8  
Old November 5th 06, 06:48 PM posted to sci.electronics.repair
external usenet poster
 
Posts: 191
Default Repair of Crystal Phono Cartridges ?

You are better off going to antiqueradios.com forums for advice . I have
tried to rebuild cartridges with poor results . It seems things get
critical for good sound . Its better to take the element from another
modern cartridge .

This guy doesnt charge to much http://membres.lycos.fr/oldradioz/

  #9  
Old November 6th 06, 01:35 PM posted to sci.electronics.repair
external usenet poster
 
Posts: 420
Default Repair of Crystal Phono Cartridges ?

On Sun, 5 Nov 2006 08:08:33 -0800, "Blake"
wrote:


"Ross Herbert" wrote in message
.. .
It must be a pretty big cartridge if it will take a 15mm diameter
ceramic disc. In my experience, the crystal/ceramic element in a phono
is quite small so I think you are not going to have any success in
repairing it. The elastic suspension carrier for the element might
have deteriorated as well so you will probably find this a problem.

Not to put too fine a point on it, why not just buy a new ceramic
cartridge and save all the hassle? Though looking at some of the
prices here http://www.turntableneedles.com/brow...cts/Index.html
you might not like it.



Thanks for the reply.

Actually, I've already examined the failed cartridge. The old crystal seems
to be a slab about 15mm long and 10mm wide, fitting into a space 15mm wide
and 25mm long inside the cartridge shell. I thought I might be able to grind
the sides of that circular 15mm barrium titanate piezo on a belt sander to
adjust the fit. Or if it shatters on grinding, find a slightly smaller one.

My old crystal was clamped into the cartridge by two rubber blocks, one
glued to the top shell and the other to the bottom. The gap between measures
about the same as the crystal thickness. Are these what you mean by the
elastic suspension carrier? There was also a thin, crumbly black coating on
the white crumbly crystal. I took this black coating for a conductive
electrode, but if this is an elastic suspension, then I might need to
understand its function better. Maybe the barrium titanite can go without a
coating. Or I could dip it in the kind of liquid rubber they sell for
coating tool handles. This point bears some more consideration.

As for buying a new cartridge, well . . . You guessed right about my
willingness to invest cash in the project. This phono isn't a fine antique,
and would probably not fetch more that $25 after I finish the repairs. But
more importantly, I wouldn't learn anything or have any fun by hiring a
specialist to do the job for me. And we're all in this for the fun of it,
aren't we?



I can well understand your desire to achieve satisfaction from fixing
something for little or no cost, and I certainly wouldn't try to stop
anyone from "having a go".

The last time I opened up a crystal phono cartridge was back in the
50's so I don't remember all the details. I am fairly sure the
Goldring cartridge I pulled apart didn't have a slab as big as in your
unit. I do remember that the crystal was very easily damaged. The
crystal element was superseded by a ceramic element in the 60's and
these were much more robust.

You might be lucky enough - with great care - to whittle down one of
the elements you are looking at as a replacement and then succeed in
mounting it along with its soldered connections so that it produces an
output. However, I don't think you would be pleased with the sound it
produced if any. Give it ago and see what happens. You can only try
and if it doesn't succeed then it hasn't cost anything except a lot of
labour, and that can be considered free in your case I suspect.

I once tried a similar resurrection project with a 1930's model
telephone right down to rewinding the induction coil since I couldn't
find a suitable replacement. While it did work to some extent it was a
failure in my estimation. In your case however, you are still able to
get new replacement parts for your project, so if I were you and I
really wanted to get it working as near to original as possible, I
would tend to opt for a new cartridge. That way you would get the
desired result and satisfaction at the same time.

Good luck.
  #10  
Old November 23rd 06, 05:15 AM posted to sci.electronics.repair
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Posts: 3
Default Repair of Crystal Phono Cartridges ?


Blake wrote:
A common problem on old phonographs with crystal cartridges seems to be that
the Rochelle salts crystal disintegrates with humidity. I'm working on one
of these phonos now. I have an idea how it might be repaired, but rather
than reinvent the wheel, I thought I would ask how others have attacked this
problem.

It seems to me that I might be able to use a ceramic piezo element like this
one

http://www.allelectronics.com/cgi-bi...EZO_DISC_.html

to replace the old crystal inside the phono cartridge. The size is just
about right. Has anyone tried this? If so, is the output level and frequency
response comparable to the original crystal?

Or is there a better approach (that doesn't cost more than an old phonograph
is worth)?

Thanks for your comments.


 




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