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JVC QL-A7 cue dampening help

ranf1970

ranf1970

Life without music would be a mistake.
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Hey Fellow AKers,

I didn't want to hijack the thread by stencil, but I'm having the same problem with my JVC (tonearm shooting up like a rocket at the end of a record, hitting the cover at times...:no:).

I have never done this before so I'm relying on your knowledge and ability to talk to a novice on how this is done. I'm not even sure what would be the best kind of oil.

I have both the owner's and service manual but they mention nothing. Any help is truly appreciated!
 
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See my posts in the thread by Stencil regarding his problem with a Yamaha TT. I restored a QL-A7, but I don't remember exactly what the cueing assembly looks like. Basically the same techniques will apply for both TTs.

BTW, my main TT is a QL-Y7. Love those JVC's.

Jon
 
Thanks Jon! I appreciate it. Fortunately when I lower the tone arm down, it goes slowly, so that isn't the problem. I have tried playing the Arm Lifter Height Adjustment screw but still the same.

I'll try opening the bottom of this TT this weekend and taking a look. I'm hoping this repair will be easy because I have no knowledge or TT repair. Of course, there is no better time than the present to begin to learn! Am I still looking at going to a hobby store and getting the oil that Howard (Hakaplan) recommended? What weight should I get?

Yes, JVC tables are great! I'd like to also get a Denon one day. :yes:
 
If it lowers slowly then I don't think it's the damping fluid. The same fluid damps up and down via the viscosity acting on the shaft. Are you positive the arm has been properly balanced per the owners manual and the tracking force properly set? Have you closely observed the cueing as it acts on the arm when it returns? If so, can you see anything that is causing it to jump? The arm is merely resting on the cueing mechanism, so the only possibilities I can think of are improper tracking weight or some defect in the actuating mechanism (something bent, out of place, or???) The latter sounds unlikely, but it could be.


Jon
 
jnoyes said:
Have you closely observed the cueing as it acts on the arm when it returns?
Click to expand...

I know I'm going to sound stupid, but the arm is supposed to return? For me, at the end of the record, the arm pops up and the platter stops spinning.

**EDIT**

I was watching this video of the QL-A7 on Youtube (http://www.youtube.com/watch?v=RZs7aFwXQPM) and noticed a couple of things. For one, the tonearm movement is smooth. When I lower mine, the arm drops at the same speed as the lever. If I drop it down quickly, like the video, then it drops like a rock. If I move the lever slowly, the arm comes down slowly. I noticed with this video, it went down slowly even with the lever being moved quickly. At the end, mine shoots up where this one raised only an inch or two.

I'm using a Nagaoka MP-11 cart, which requires a stylus pressure of 1.8-2.3g. I have it set at 2.0. I also have the anti-skating put at the same.

I hope this makes sense.
 
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Actually, TTs can be quite complex. No need to feel bad for not knowing. We all start somewhere. It's been a while since I had the QL-A7. Looking at the manual, this is a semi-auto TT. The arm should raise at the end and the platter should stop rotating, but the arm doesn't return to rest. Something must be amiss in the mechanism. The service manual or owners manual are really not much help in trying to figure this out. Have you tried the lifting mechanism adjustments in the owners manual? I doubt that's the cause, but maybe. You might have to remove the bottom cover to see if anything looks out of place. Pictures would be helpful.

Jon
 
Thanks Jon! I edited my post with a little more info/video. I'll see about opening the hatch and taking some pics. I realized the same thing with the owner's and service manual...:no:
 
OK, from the added info it does sound like it needs damping fluid. I think there is info on removing the mechanism in either the owners or service manual. I seem to recall that the mechanism can be removed from the top. Let me check in the manuals. If it needs fluid we'll get it fixed.

Jon
 
Service manual page 6 describes how to remove the lifting mechanism. Looks like it comes out from the top. No need to remove the bottom cover. Send me a PM.

Jon
 
FYI, the sales flyer available at Vinylengine describes the operation of the arm lifting at the end of play and provides pictures and a block diagram.

Jon
 
It definitely sounds like a damping issue. Trying what Hakaplan suggests is probably the easiest solution. Obtain either the 300k or 500k silicon oil (another source is auto supply store where its marketed as differential fluid) -- the different viscosities determine the rate at which the cue lifts. A measuring syringe to apply it to the cueing piston and then working it up and down until the oil works its way in. At least try this method before you to go to the trouble of disassembling the mechanism.

Good luck.
 
4dryhme said:
It definitely sounds like a damping issue. Trying what Hakaplan suggests is probably the easiest solution. Obtain either the 300k or 500k silicon oil (another source is auto supply store where its marketed as differential fluid) -- the different viscosities determine the rate at which the cue lifts. A measuring syringe to apply it to the cueing piston and then working it up and down until the oil works its way in. At least try this method before you to go to the trouble of disassembling the mechanism.

Good luck.
Click to expand...

Yes, it sounds like it needs damping fluid and you can try to get some on the shaft from the top; however, for proper, long term operation the entire shaft needs to be coated. You can try lifting the shaft to get more in.

Since the mechanism can be removed from the top. it's not like the TT needs to be disassembled. The mechanism really isn't that complicated, but of course, not everyone is comfortable with working on mechanical things.

I agree that in the short term you should try Howard's (Hakaplan) suggestion.

If you want to go the full route, I'll be glad to help.

Jon
 
Thanks 4dryhme and Jon! I think I'll go the full route. No better time than the present to learn! :yes:

Does the weight matter or are either OK? I assume 500K will make it lower more slowly than the 300K? Oh, and which shaft are you referring to?

PM sent. Thanks again!
 
ranf1970 said:
Thanks 4dryhme and Jon! I think I'll go the full route. No better time than the present to learn! :yes:

Does the weight matter or are either OK? I assume 500K will make it lower more slowly than the 300K? Oh, and which shaft are you referring to?

PM sent. Thanks again!
Click to expand...

No problem! And your assumption is correct -- someone reported trying the higher viscosity made the cueing too slow...It's matter of taste I believe. Some manufactures are quite specific about which viscosity to use and some don't mention it at all.
 
4dryhme said:
No problem! And your assumption is correct -- someone reported trying the higher viscosity made the cueing too slow...It's matter of taste I believe. Some manufactures are quite specific about which viscosity to use and some don't mention it at all.
Click to expand...

I didn't see anything mentioned. I'll look more closely. If that's the case, then it might be better to stick with 300K.
 
ranf1970 said:
I didn't see anything mentioned. I'll look more closely. If that's the case, then it might be better to stick with 300K.
Click to expand...

I should have added that the guy who reported the cueing working too slowly wasn't using a deck like yours. I can't remember what it was, unfortunately.
 
I used 300k on all the TTs I've worked on (including 4 JVCs) and it worked well. I think 500K would cause the damping to be too slow.

I caution that you will be working with some very small parts that can easily be lost, roll off the table, or pop away (springs). A cloth on the work space would help. You will need a set of jewelers screw drivers.

Take pictures as you go to ensure you know how things go back together.

Jon
 
Thanks again to everyone! I'm going to try to get some oil and tackle it this weekend.
 
I fixed mine with 125000 weight silicone oil that is sold at bike shops for skateboard wheel bearings (Losi brand). It worked great and was readily available. When you do it, be patient. The stuff is so thick that it takes quite a while to settle in the groove where it needs to go. It was 24 hours or more before I saw the full benefit.
 
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