JVC JL-A20 running slow

[inertialwave]

JVC JL-A20 turntable slow..the measurements

So to continue...I used Panef white lithium grease
http://www.panefproducts.com/grease.htm

Mine is about as old as the JVC so it was pretty sticky. I am definitely going to re-lube with a new tube...or does anyone have a better recommendation?

BTW The attached pdfs show the old JVC runs with the initial re-lube.
Speed vs time.
Speed vs time zoomed
Speed Power Spectral Density (PSD)

I plan to redo these measurements after re-lubricating with new grease.

 

[jkilla]

So I had to pay a visit to my dad who has a vice in his shop that I was able to PRY the damn spindle apart. I just couldn't believe hardened grease could grip that sucker to the point where I thought the centre spindle was incapable of spinning!

I'm going to try some sewing machine oil as a form of lubricant that is what I've been recommended, you can give a try as well, although I'm sure I can get a hold of some white lithium grease as well.

Thanks for all the help, I might be able to get this thing to work properly finally after dragging it home over a year ago!

 

[inertialwave]

No problem. Without your original post back in Aug 2012 that started the thread we both would be looking at a frozen spindle today ! Kudos to you and all the AK members who responded.

Basic problem is that the manual did not foresee we Earthlings would be operating the equipment after 34 years of inaction and didn't put any mention of the spindle bearing or lubrication of the spindle in the owner manual. Hope this now leads to some enjoyable sound from your old JVC JL A20.

You can go ahead with the oil lube and I will do a a spindle clean and re-lube with the new tube of white lithium grease I just bought. Should be pretty quick from the top now. I will redo the spin speed test and see if it helped. Let me know how the oil worked out.

 

[inertialwave]

JVC JL-A20 turntable slow..w/new spindle lube

Well with new white lithium grease on the spindle speed is up 0.3rpm to 32.64 rpm and speed noise is down a bit as well.(see attached files). Even still, to my ear the "The Beatles 1962-1966" (red vinyl album) sounds just as good as the "The Beatles 1967-1970"(blue vinyl album) I reported on earlier.

Sure was nice to be able to quickly service the spindle bearing from the top. And this time I really scrubbed the shaft and housing down and found a present inside !! A tiny ball bearing dropped out. Sure enough there is a tiny pocket in the case bottom to hold it. I guess it is to keep the shaft bottom from rubbing on the case bottom and also keeps the shaft cutout centered on the retaining screw. The latter feature prevents anyone from pulling out the spindle shaft. So I carefully cleaned everything, applied a sparing lube film and reassembled it all.

 

[jkilla]

It's alive!!! Works, speed is steady and very close on (I would wager it's around the same RPMs, 32-33 just by my guess since I don't have any instruments to measure with)

The auto return is quite messed up, as it returns to the tonearm rest but then bounces back onto the platter and then drops the stylus into a gap between the platter and the plinth. Sounds nightmarish, I know, but right now if I use it as a manual table, it is very enjoyable for sure!

 

[inertialwave]

Hey, good to hear your old JVC is now alive ! (Thanks again to the AK Forum)

Sorry about your auto-return issues...I am the original owner and mine works great. I am just getting into checking the tone arm balance and skew.

I have been posting my speed plots (based on a developmental sensor) as attachments. The new white lithium grease helped but I am now wondering about the sewing machine oil you are running. As soon as I calibrate my data I may open a post on spin speed measurement methods and accuracy and what the various turntable speed noise components may be saying and how they may be reduced.

 

[jkilla]

Great news! The auto return problem was really easy to fix. Turns out a very common problem with this family of Jvc tables is that there is an arm inside the turntable that is responsible for making the tonearm return. On this inside arm, there's a sponge that is almost always worn out / disintegrated after the 30+ years of being on the table.

All I had to do was stick a piece of folded light cardboard (business card) and the autoreturn is back in action.

http://www.vinylengine.com/turntable_forum/viewtopic.php?f=18&t=43437& contains more instructions and pictures.

Definitely feel that I underrated this table in the past. It sounds very nice for something I salvaged from a yard sale for $3

Sent from my SGH-T999V using Tapatalk 4

 

[inertialwave]

Good to know. Nice link to the fix. My JVC-AL20 is playing nicely as I type this. I will be sure to follow your posts if I encounter any issues.

 

[Snohomish]

Sorry to leave you hanging...had difficulty getting onto the forum for the first time...

Sounds like your spindle is frozen like mine was. So here is what I did.
1) unscrewed the set screw on the side of the spindle case (back it out all the way)
2) carefully but firmly pulled the central spindle out of the case -- I used a vice to firmly hold the case and a pair of grips to pull on the spindle. (use protective material to protect the surfaces and don't over tighten - it should pop with a bit of force - its only dried grease holding it.
3) use liberal alcohol to clean the spindle shaft and case of old lube
4) re-lube with something long lasting -- I used some old white lithium grease I had and it runs great to the untrained ear..but I am going to by a new batch and redo it soon. (I am curious to see if my speed increases to spec 33&1/3 rpm from ~32.2-32.4ripm-- will post some plots later)

Inertialwave's posts are right on! I had a spindle issue with the same model TT, pulled it out from the top of TT, cleaned and relubed it, and now I'm listening to Workingman's Dead on my vintage JBLs and it sounds great. I also had a noticeable motor hum that I thought might be helped once the spindle was spinning freely, but no go. So for what it's worth, be advised I found the three rubber grommets that insulate the motor from the chassis, accessible from inside the TT and on long bolts, were compressed to the point of leaving metal on metal, hence the vibration and hum. I added a cut-down felt furniture pad (about 1/8 in. thick) on each grommet (punched a hole in each so it went over the bolt), and problem solved. Over the years rubber will shrink even if it does not look or feel like it has.

 

[gr33nhorn]

Another thing to check while troubleshooting for speed -
make sure that the belt is resting correctly on the middle of the pulley section , and not rubbing on the pulley sides or the selector - you'll hear a slight scraping sound otherwise

 

[4MarkNY]

What's better than AudioKarma?
This thread got this old JVC JL-A20 running right in 10 minutes after reading through it. needed sewing machine oil in the motor, and the spindle pull & lube.

Thanks to you all!

MarkNY

 

[CaptainJack]

Interesting thread. I also have the A20 running slow, though it has been fine for about 10 years.

To try and remediate, I have:

1) Greased up the platter spindle (it wasn't locked up at all, like some here)
2) Renewed the belt - the original one was slipping rather badly

I am waiting for some sewing machine oil to grease up the bearings in the motor. Will probably take it apart and clean stuff out of it. That said, it seems to rotate freely, so not sure how much difference that will make.

I've also adjusted the spindle height on the motor as per service manual but no change. The rubber mountings for the motor seem quite saggy, so I'll probably pad them, but not sure how that can affect the speed.

BTW, I am in UK, so on 50Hz mains.

 

[Stormwatch]

Just fixed the speed of mine with your help guys. Thanx!

 

[CaptainJack]

Just fixed the speed of mine with your help guys. Thanx!

How did you fix it? I wrapped Teflon tape around the roller to speed it up - no amount of lubing the motor helped and it runs very smooth.

 

[Stormwatch]

I dissasembled the center spindle. I thought it was one piece but with a little extra effort I managed to seperate the two pieces, clean and lubed them and now I get almost perfect speed. The funny thing is that in the service manual there is no mention that you can do that.