Probably asked a thousand times all ready, but I'm gonna ask anyhow. How can I fix an inconsistent speed on a direct drive Realistic Lab-500 turntable? It's fine on 33, but on 45 it won't stay steady, causing "WOW". The Quartz lock ain't stayin' locked...

It has two PC boards underneath, and it looks like there may be another inside the motor assembly. Is it simply a capacitor that needs to be replaced? And if so, any idea which? Anyone have a schematic, so I can see which capacitors would be on the 45 rpm circuit? Or is there something else?

Thanks,
Gerry

Probably asked a thousand times all ready, but I'm gonna ask anyhow. How can I fix an inconsistent speed on a direct drive Realistic Lab-500 turntable? It's fine on 33, but on 45 it won't stay steady, causing "WOW". The Quartz lock ain't stayin' locked...

It has two PC boards underneath, and it looks like there may be another inside the motor assembly. Is it simply a capacitor that needs to be replaced? And if so, any idea which? Anyone have a schematic, so I can see which capacitors would be on the 45 rpm circuit? Or is there something else?

Thanks,
Gerry

Hi, Have any pictures of the inside? Would help us help you , there are usually mini pots for speed adjustment on these TT's because the 45rpm is working, Cleaning them usually works.

Vinylengine.com might have manual or schematic for you.

John.:music:

It has been asked a thousand times and you will be penalized for not paying attention!!! :nono:

Start by spraying deoxit on the innards of the 33/45 switch. That usually solves the problem.

If that doesn't work then yes as John recommended, if you see 33 and 45 speed adjustment pots, you might try spraying it on those. But if you mess with those it might be tricky to get the speed back to where it should be, so just try the 33/45 switch first.

Oh my goodness! It's THAT simple? :stupid: I saw the two little pots on the one board, but I never thought they would need cleaning since they don't get used like ordinary volume or tone pots. I didn't want to touch them, since they would be a pain to get them back to where they should be, what with them being underneath and not having a strobe disc or anything.

I'll give it a shot - or two - and see what happens.

Thanks!

I've never seen a LAB 500, so pictures are a required offering to the AK gods.

Welcome to AudioKarma!

As you wish.

Cool. Very nice. :thmbsp:

The gods are appeased.

The LAB 400/420 decks are on my "look out" list.

It has been asked a thousand times and you will be penalized for not paying attention!!! :nono:

Start by spraying deoxit on the innards of the 33/45 switch. That usually solves the problem.

If that doesn't work then yes as John recommended, if you see 33 and 45 speed adjustment pots, you might try spraying it on those. But if you mess with those it might be tricky to get the speed back to where it should be, so just try the 33/45 switch first.

You tell em Howard Lesson 101 on Turntables is:
If it's running crazy and the speed is off Squirt those speed pots with some good contact cleaner.
Ok off to the corner with you and repeat to your self.
I will clean speed pots with contact cleaner
I will clean speed pots with contact cleaner
I will clean speed pots with contact cleaner
I will clean speed pots with contact cleaner
Seems to work on almost all tables with speed issues.

Nice table!

...and squirt, squirt, squirt I did. Guess what? It didn't work.

The speed on 45 rpm is still wonky. Just like someone is randomly pressing their finger down on the platter every few seconds to slow it down. Not an issue on 33 rpm. One thing I noticed while the platter was off: the spindle doesn't turn smoothly. It's jerky - like a second hand on a quartz clock. Is that how it's supposed to behave? Does it on both speeds, yet with no detrimental effect on 33. Is inertia from the platter what keeps it going smoothly, and the pulses are more like gentle pushes to keep up the speed? Is that how it works? Or should the spindle turn smoothly while running without the platter in place?

Bottom line is that spraying the pots and speed switch did nothing. Now what?

No, the spindle is supposed to act that way--it's not getting proper feedback. Direct drives are meant to run with the platter on.

When we said spray, we also meant to work the pots and switch all around--sometimes it takes a lot of working and multiple spraying. Did you do that? That's the only way to completely clean dirty switches and pots.

Yes, the pots were thoroughly cleaned, and are functioning. The speed changes when I turn them, but is still inconsistent on 45 no matter how fast or slow it is set. The switch and pots are not the problem. Seems more like a power fluctuation, as it slows down briefly at fairly regular intervals, every two to three seconds.

just because you cleaned the switch and the problem is still there doesn't mean the switch isn't the problem. A faulty power switch can also cause this symptom so check that too.

I would disconnect the switch and ohm it out. See if the reading remains constant in both positions of the switch. If it fluctuates sitting there or when you tap on the switch - it is bad. A quick remedy is to hard wire it for the 33 speed.

If the problem is still persistent even after the switches are confirmed good, then look to the power supply and see if the voltages dip when it slows. If so then you've located the problem. If not move to the controller and look at voltages on the IC, You can look up the IC for a pinout if you don't have the service literature . If you have a scope measure the feedback pulses to make sure the controller isn't getting erroneous data from the motor feedback coils. Check capacitors for ESR and leakage. Don't have an ESR meter? you can build or buy one. Very useful tool in troubleshooting.

Worst case scenario something is wrong about the DD motor.

Well, after TWO DAYS of spraying contact cleaner and twisting the pots and flipping the speed switch, I am finally seeing some improvement. The pitch is not dropping quite as far, nor lasting as long. Naturally, the can of contact cleaner is now empty. HMM, what to do? I finally decided to pour some 90% alcohol on and continue with the twisting and flipping. ONE dousing of alcohol made the most dramatic improvement! Now the pitch drop is only very slight, and the duration much shorter. Today, I shall continue the alcohol bathing, and I bet that cures it. Don't know why the electrical contact cleaner didn't seem to phase it, but the alcohol did. Normally, the cleaner works fine on pots, although it often takes about three applications (or more). I think from now on, I'll just start off using the alcohol. Takes a while to dry, but works so much better!

What brand of contact cleaner were you using originally Gerry? Most of the folks here (me included) prefer DeoxIT over other brands. I've seen situations where a pot or switch that wouldn't clean up with other cleaners, did so quickly with DeoxIT. I've had such good success that Caig products are all I use these days.

Not sure what brand it is... QD? QC? I don't know. It comes in a standard-size can with a blue label for about $6 at the local hardware store. I sometimes use another little can called "Jiffy Bath" with lubricant in it, but it is also expensive at $6 for about a 3- or 4-ounce can, and is a 20-mile round trip to get at the one electronics store here in Maryland. I used to do most of the cleaning with the cheap stuff, followed by one or two shots of the "Jiffy Bath," but I've run out of that. They also have DeoxIT, at that store, but it's a whopping $14 for a tiny little can, about the size of a can of mace or pepper spray. I know just about everyone prefers the DeoxIT, but it's just not in my budget right now, being unemployed, and I only make the trek to that store when I need several things AND happen to have the money. If only it were a full-size can, I might be willing to invest in some.

What brand of contact cleaner were you using originally Gerry? Most of the folks here (me included) prefer DeoxIT over other brands. I've seen situations where a pot or switch that wouldn't clean up with other cleaners, did so quickly with DeoxIT. I've had such good success that Caig products are all I use these days.
Exactly, and that's because it not only cleans, but deoxidizes. Although it seems to be working alcohol may not be the best thing to be using. There's got to be a reason it's not widely recommended.

Not sure what brand it is... QD? QC? I don't know. It comes in a standard-size can with a blue label for about $6 at the local hardware store. I sometimes use another little can called "Jiffy Bath" with lubricant in it, but it is also expensive at $6 for about a 3- or 4-ounce can, and is a 20-mile round trip to get at the one electronics store here in Maryland. I used to do most of the cleaning with the cheap stuff, followed by one or two shots of the "Jiffy Bath," but I've run out of that. They also have DeoxIT, at that store, but it's a whopping $14 for a tiny little can, about the size of a can of mace or pepper spray. I know just about everyone prefers the DeoxIT, but it's just not in my budget right now, being unemployed, and I only make the trek to that store when I need several things AND happen to have the money. If only it were a full-size can, I might be willing to invest in some.

Yes, DeOxit is pretty expensive little can. But it goes a LOOOOONG way. I been using DeOxit (same can) for a few receivers and it's still plenty left. I've read alot about other contact cleaner don't do as well as DeOxit. Since you said you used alcohol to cleaning pots and switches. Worse thing happens to the pots is they will wear out very quickly since they're starved of lubrication that DeOxit (Faderlube) provides. DeOxit D5 also provides some kind of lubrication for switches. I know you are trying to skimp on the cost because you're unemployed at this time, however you lost 6 bucks for the cleaner that didn't remedy your problem and you would have only needed another 8 bucks to get the DeOxit if you would have waited a little.

Well, the cheaper stuff - both kinds - have lasted me nearly a year. Using the combination of both seemed to work, and gave me the option to use just the one without lubricant for some things. Howard, you're probably right about not using alcohol. My worry about it was that the water in it may actually cause rust if things stay wet too long. What I did was prop the turntable up in front of a fan to help dry it more quickly. While it did seem to work at first, I notice that after a while, the problem comes back - usually goes away on its own after about ten minutes. Just intermittently as the turntable starts up after a period of rest. Nowhere near as bad, but still wonky-wobbly sounding.

Not only the lack of funding was holding me back from buying the DeoxIT. I was also having a hard time with the fact that it cost more than the $8 I paid for the turntable! True, I can use it on many other projects, but I generally don't refurbish very many stereos in the cold months. (I work outside in the shed or out on the patio, so summer is my busy time.)

Fortunately, I just received an email that someone wants to buy one of my Magnavox console stereos I have for sale on Craigslist. So now I can use the money from that to buy one of the 5 oz. cans of DeoxIT. So, is the "D5" the version that I want? Who has the best deal?

If there's a Guitar Center near you, they sell it for $12.

A quick Google search revealed that there is indeed a Guitar Center just a block away from the expensive electronics store. They show the 5 oz. can "D-5" for only $11.99. And it just so happens I'll be going past that area on Thursday morning. Thanks!!!

Always listen to Howard, he's the man! And the 'cleaning the pots' trick worked on my SL-1700 like a charm!!

The DeoxIT finally worked, particularly after it sat overnight. Of course now the speeds are no longer set properly. Best I could do was play two copies of the same record, one on another DD turntable, and match the pitches. Tried those downloadable strobe discs, but they didn't work, even with a fluorescent light. Just looked like a solid line... Well, I got it close enough, I suppose. Thanks for everyone's help.