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How to remove the TT-71 motor from a JVC QL-7 turntable

mjw21a

mjw21a

Super Member
Hey guys, I'm currently trying to figure out how to remove the TT-71 from its plinth on my JVC QL-7 turntable.

I want to do this so I can veneer the table. I'll be swapping out the Victor UA-5045 tonearm for a Fidelity Research FR-54 while doing this too. Should be sweet once done :)
 
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mjw21a said:
Hey guys, I'm currently trying to figure out how to remove the TT-71 from its plinth on my JVC QL-7 turntable.

I want to do this so I can veneer the table. I'll be swapping out the Victor UA-5045 tonearm for a Fidelity Research FR-54 while doing this too. Should be sweet once done :)
Click to expand...
I've been wondering how that project has been going. If the design is anything like my Technics SP-15 (also DD with a separate motor unit) there should be something like four screws you will find after lifting the platter. It seems to me that the Denon DP-1200 I once had was similar. Maybe (carefully, I don't know if there is some magnetic strip to mess up) pull the platter, take a pic and post it? One way or another I'd wager the screws go in from above rather than from below as you would see those pretty readily if they were present.
 
fiddlefye said:
I've been wondering how that project has been going. If the design is anything like my Technics SP-15 (also DD with a separate motor unit) there should be something like four screws you will find after lifting the platter. It seems to me that the Denon DP-1200 I once had was similar. Maybe (carefully, I don't know if there is some magnetic strip to mess up) pull the platter, take a pic and post it? One way or another I'd wager the screws go in from above rather than from below as you would see those pretty readily if they were present.
Click to expand...

That makes sense. I was looking from underneath and couldn't see anything.
 
mjw21a said:
Hey guys, I'm currently trying to figure out how to remove the TT-71 from its plinth
Click to expand...

I should think its the same as my TT-101/QL-10, lift the plater and the perimeter has 3 holes for securing.
Are you doing anything to the stock plinth other than veneering?
 
ETI_5000 said:
Although it’s the model below the QL-7, there may be enough similarities that the service manual from the QL-5 gives you some idea – it has an exploded view showing where all the screws are holding all the parts together on the plinth.

See http://www.vinylengine.com/library/jvc/ql-5.shtml . Good luck.:music:
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I see some longer screws in the diagram that look suspiciously like they might be holding the drive down...
 
When you get the drive removed could you measure the diameter of the opening in the oem plinth,

I know as the models increase QL-7,QL-8,QL-10/Japan 100v TT-101, the depth of the "can" increases but
was curious if the diameter changed also.
 
totem said:
When you get the drive removed could you measure the diameter of the opening in the oem plinth.

I know as the models increase QL-7,QL-8,QL-10/Japan 100v TT-101, the depth of the "can" increases but
was curious if the diameter changed also.
Click to expand...

The TT101 hole is 292mm. This is from someone who has one and made a custom plinth. I have a TT81 motor unit, but no plinth yet. I'm also told that the fitments are the same. My motor unit is not tapered and I doubt if the original plinth is. Also, there are cooling vents near the top and a small space between the plinth and motor unit, so it might not be a good idea to taper.

Mine came with 3 long brass bolts to mount the unit. If you remove the platter you'll see the slots for them. I think they are 5mm, but I'll probably replace with 1/4" because threaded inserts are easier to source. If you make a plinth out of slate, cement, or some kind of similar material it might be a good idea to use rubber washers between motor unit and plinth.
neo
 
neobop said:
The TT101 hole is 292mm. This is from someone who has one and made a custom plinth.
Click to expand...

How are thing's?

Just to clarify for the record I have owned a TT-101 for some time now and am waiting on some fasteners to complete a plinth.
The diameter of the opening needed to drop into a plinth with "minimal clearance" is 281 mm or 11 1/16" approximately, this allows for the
fasteners holding the metal can.

I think the TT-81/QL-8 and maybe the TT-71/QL-7 might be the same [diameter] but can't confirm as I have not owned one.

These 3 models differ in height or to be more precise the depth of the motor and its metal can that surrounds it.
In the case of a TT-101/QL-10 that is about 3 1/2" or 89 mm or so.
 
neobop said:
292mm leaves a little breathing room and is sufficient to support the motor. This is from Halcro who has a new granite base:
Click to expand...

I see where we differ, Halcro and I. The smaller diameter is needed if you want to secure the table with the
existing mounting holes in the rim. In his example the Table is resting on top. I drilled and inserted threaded fasteners.

And my appoligies to the OP for going on a tangent from his TT-71 topic.
 
totem said:
I see where we differ, Halcro and I. The smaller diameter is needed if you want to secure the table with the
existing mounting holes in the rim. In his example the Table is resting on top. I drilled and inserted threaded fasteners.

And my appoligies to the OP for going on a tangent from his TT-71 topic.
Click to expand...

I was told the TT71 has the same fitment, so it might be relevant?

Halcro said his table is bolted to the base. In the motor unit I did notice slots for these bolts, instead of holes. Wouldn't there be enough room if the edge was 5.5mm further out?
I'm waiting on a carpenter for some custom parts I'm going to incorporate in the base. I don't think he's started yet. Maybe I should change the hole size before it's too late.
neo
 
neobop said:
I was told the TT71 has the same fitment, so it might be relevant?
Click to expand...

I can only comment on the TT-101, it has bolt holes not slots but in my case adding the threaded insert brings
the drilled hole precariously close [for me] to the outer motor diameter.

In fact to ameliorate the problem I machined aluminium bushings inserted into the mounting holes
and center drilled to allow a smaller 4mm dia fastener to be used and thusly a smaller threaded insert.

Note the hole in the 101 is maybe 7mm so any threaded insert would have a larger dia and moving the required hole closer to the
edge. Thats why I went with the bushing and 4mm to be safe and made the plinth opening
as tight as it is.
 
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