MCS 6502 weak/poor sound quality

[gotitforfree]

I came across a clean looking older MCS turntable yesterday, it was left behind by a tenant in a house my boss rents. (So was the rest of the system but most of the rest of the system was all black plastic late model junk).
I snagged the turntable and two crates full of albums and about 500 45's.
I brought the thing home, gave it a good cleaning, sprayed all the pots with some deoxid from the start and gave it a try. What I got was nothing but weak, garbled sound, it sounds like someone singing underwater or with a mouth full of cotton.
There was a spare stylus, so I went ahead and swapped that out but it made no difference. I then swapped out a complete cartridge from another turntable I had laying around and it made little difference. The only change with the cartridge change is that there's now a difference between the sound from a 45 and a 33 rpm record. The 33 rpm records will play but at a very low volume. 45 rpm, (7"), have more volume but sound all distorted or garbled. It also has issues tracking with on a 45, but seems fine on 12 inch records. I tried moving the counter weight up to increase the weight on the record but the tracking didn't improve.

What gets me is that the guy who left this behind was using it, it was set up as the only input to a black Pioneer surround sound receiver with an external phono preamp.
I did try the phono preamp through my aux jacks too but it does the same thing.
I removed the bottom of the turntable and I really don't see much in the sound path that could do what I'm hearing. The wiring seems to go right through the cartridge to the L&R cables to the amp. Both cables ohm out fine. The used cartridge I swapped in came from a turntable I gave up on after it had mechanical issues, but that was 10 year ago.
I was thinking about buying a new cartridge for the MCS and trying that but am not sure what to get?
The original has an Audio Technica logo on the front but no numbers I can see. The head shell is not detachable but the cartridge mounts with two vertical screws like most others.

 

[WaynerN]

I just finished restoring one. The arm is less then desired on these tables. I replaced mine with the AR tonearm. The arm that came with mine was loose at the pivot points and a couple of wires were broke, so the mod decision was a no problem. The motor and electronics are basically a Technics SL-23 so there is something to start with.

I also ripped out all of the features that made it an automatic, so that means I had to install a new power switch.

Here is mine.






Wayner

 

[gotitforfree]

The tone arm feels okay on mine, it moves freely and has no play in any direction. The ramp or lifting bar though seems drag on the arm when its playing, the top of that bar is rubber and its always in contact with the arm. This only happens on 45's, it tracks fine with 33's.
Its the sound issue that's the main concern, I've never heard a cartridge create this type of distortion before, the needle looks good, or at least I don't see any wear looking at it through a magnifier. Both channels make sound and are equal in volume.
I checked all four wires and they show no resistance or open circuits from the head shell to the RCA plugs. When I saw that I had just figured swapping in another cartridge would get it working again but no such luck. I can't figure why it will play 33's, (although at a very low volume), but it won't play 45's? Its not arm position because it will play the 33 to the end.
The low volume issue also has me stumped, as an example, the volume is numbered 1-10, if I'm playing a tape at 2 on the volume control, which is slightly louder than what I'd call normal listening level, I have to crank it up to 8 to get the same volume out of the turntable. It did the same thing using the phono preamp and running through the aux ports as on the phono jacks, which I did to make sure the phono inputs were working okay. I know records won't be on the same level as a tape or CD but this is so weak you can't hear it unless your sitting right in front of the speakers. On phono, its no louder than a set of headphones laying on the table playing. Adding weight to the tone arm does make the 45's play louder but not any clearer.

The used cartridge I put in this thing was replaced for noise issues, it played fine but had static issues but it did play. I really expected swapping the cartridge to make it play but to be just noisier than it should be. When I took this off my old turntable years ago, I went through a few replacements before I found one that gave me good sound, if I remember right, when I replaced it with the same model back then it didn't make much difference in the sound issue I was trying to fix which is why I assumed this cartridge was likely still good. I had upgraded that cartridge with a more expensive one back then and solved that turntables issues. I sold that turntable before I moved here, and haven't had one since.

My receiver is an old Pioneer SX 650 that I bought in 1978 along with a Pioneer PL516 turntable. The turntable died years ago, I gave it away when the motor died in the 80's.
The PL516 played great, I never once had an issue with it back then. I've never since been able to find a turntable that played anywhere close to that one and could never figure out why.
I think the cartridge was made by Shure but I never looked at it close enough back then to know the model number.

 

[Keldog]

I hope you get an answer to this. I have a 6502 already and am very pleased with it. So much so, that I just purchased another one and it's on its way. The seller described it having an issue with it much the same as yours. But I figured it is because they didn't know enough to hook up a turntable correctly. If there I figure something out before there is another answer, I'll let you know. It will be well worth it if you fix the issue and are able to enjoy it.

 

[rothwellaudio]

The turntable only turns the record round and round at a constant speed. If it's doing that, it's working correctly.
The tonearm only has to hold the cartridge and let it track the groove. If it's doing that, it's working correctly.

That only leaves the cartridge, and I suspect that's where the problem lies. Check for continuity from the cartridge pins to the plugs at the end of the tonearm cable. If that's good, the cartridge must be toast (assuming the phonostage is working correctly).

 

[gotitforfree]

I bought a new $23 cartridge off eBay, it looks identical to the original one. It made no difference at all.
The thing has little to no pressure on the record. The needed will not track without adding a lot of weight
I bought another, same model TT, at a flea market for parts but it has the same tracking issues. The problem is I don't see
what's wrong, the tone arm is in contact with the lift bar at all times, the lifting bar, which is rubber coated, raises up and down with the lever but
is not going far enough down to let the arm rest fully on the record.
I took the parts TT apart but it looks like the mechanism is moving freely and can't go any further downward. If I stack three 45rpm records on the adapter it will track fine and play, although still pretty distorted. (Sounds like a radio not fully tuned in properly when it plays, both channels play, the left channel gives me a constant volume not affected by the volume.
Another TT I have plays fine but seems to play slow. (The phono inputs work fine on the amp)

 

[rothwellaudio]

What I was trying to say is that the problem is either mechanical or electrical. The turntable is really a mechanical device and as long as it is turning and the stylus sits in the groove ok (with the correct tracking force) the mechanical part is fine and the search for the problem should shift to the electrical domain, ie from the cartridge onwards. If the cartridge is fine and the phonostage is fine, the only place where the problem could be is in the wiring from cartridge to phonostage.

 

[MCS Guy]

I had a similar problem on a MCS 6500. Had weak sound on one channel. I narrowed it down to the pins in the tone arm not making good connection with the cartridge. I cleaned the ends of the pins and used deoxit on them.

Another idea to check the tone arm is to feed an audio signal down each pin and see if it makes it out the other side.

Something is amiss if the tone arm is contacting the cue lift while playing

 

[gotitforfree]

The audio comes from both speakers with weight on the arm, but one side is a constant volume, the other can be increased or decreased with the volume or balance controls.
With the stylus off the cartridge, the tone arm cannot touch the record, the cue bar won't go down far enough. Stacking three records makes up the distance it needs to track.
I can lift and lower the cue with the lever, when I put the lever down, the cue bar lowers slowly. I can't push it any farther downward once it stops but its still touching the tone arm at that point.
The second TT is the same. I tried lubricating the cue where it moves through the hole in the base but it didn't change anything.

The second or parts TT has other issues too, it randomly returns the arm to the rest regardless of position on the record. Sometimes it goes the whole distance, sometimes it parks the arm after only a little bit of play. Sometimes it also just randomly drags the needle across the record for no reason. But I only bought that one for parts. Both look like new, perfect lids, no scratches and super clean. I was surprised that either one had issues. The old cartridge I removed from the original 6502 works fine when I put it in another TT I have here, but its not quite as loud at the same volume setting.

 

[Keldog]

I didn't read anything in your posts about the adjustment screw. Have you tried it? I had to adjust mine when I got my 6502.

 

[rothwellaudio]

The audio comes from both speakers with weight on the arm, but one side is a constant volume, the other can be increased or decreased with the volume or balance controls.

The volume control is way downstream of the turntable and if it can't control the volume there's a serious problem with it, completely unrelated to the turntable.

 

[gotitforfree]

I get the same thing on which ever receiver I connect. I get badly distorted sound out of both channels, but only the right side is affected by the controls. Only this one TT does this.
Its hard to explain what its doing, its not clear sound at all, its so distorted that you can't even make out the music or voices. Adding weight or stacking records helps but doesn't fix it well enough to listen to.
I tried the adjustment screw, it was all the way in, turning it the other way raises the arm even higher. In comparing the two 6502 turntables, I don't see anything really broken or off. The platters both have the same number of shims, the screws are in the same places and the mech is secure to the wooden body of the TT. On the original TT, the return function works fine, when I can get it to track through a whole record. 45's play far better than 33's for some reason.
The tracking issue is obviously that the arm isn't able to reach down to the records, it hits the cue bar about the same time the needle hits the record.
I really don't see how there's anything amiss with the tone arm, and the cartridge is new, could the platter be too low somehow?
I did replace the belt, but there was only three very thin shims under the platter, two made from a hard, clear red plastic, and one steel shim. both are super thin, thinner than a sheet of paper. The second 6502 has the exact same parts under the platter and is assembled exactly the same way to the wood base.

Something I do notice is that I can't dial in a steady strobe on this thing at any speed. Its always wondering a bit. On my old Pioneer I could dial it in perfect.
I did clean all the controls and contacts with De-ox-it, but it made no change. When I turn the dial, the strobe is erratic and bounces all over the place. I get this from both the first 6502 and the parts TT as well. With three records stacked, the speed sounds the best all the way to the left, but the strobe is closest to 'standing still' almost all the way in the other direction.

I picked up a used Bang & Olufson Beogram RX off CL last night for $150, it plays and sounds fine, until I get this MCS sorted out, I guess the Beogram will be my main TT. It plays great but looks out of place with all my other wood tone finished components.

 

[Keldog]

All that comes to mind now is bent tone arm or bad rca cables.

 

[MCM_Fan]

I didn't read anything in your posts about the adjustment screw. Have you tried it? I had to adjust mine when I got my 6502.

View attachment 1355073

In addition to adjusting the height of the arm rest, how are you determining your VTF (I recommend an inexpensive digit scale - see below)? Are you just going by the scale on the counterweight? If so, did you balance the arm first and zero out the counterweight? What is your antiskate setting?

It sounds like your stylus is not making good contact in the groove.. If so, it could be caused by either interference from the armrest, or improper setting of the VTF.

 

[gotitforfree]

I really don't have anything to measure arm weight on the record, but I do know that its just about zero unless I stack three records and add four or five quarters to the tone arm at the cartridge. The arm is sort of S shaped and don't look bent, its identical to the one on the second 6502.

I went ahead and removed the cue bar completely, with it out of there, the arm follows and tracks fine, but the distortion is still there even with the new cartridge. I did an ohm test of the rca plugs before, all are ok, no resistance, no shorts all the way from the cartridge to the rca plugs.

The cue bar has rubber on the top, I can see where the rubber is worn where the arm has been dragging on it for a long time. I've got the counter weight all the way forward right now, for the least counterweight possible. Putting more weight on the arm still makes it sound better but its no where near acceptable.It has to be a bad new cartridge making the garbled sound, plus what ever ails the arm itself. I'm about ready to grab this thing by the cord and toss it out the window.

To top it all off, the Beogram I bought sounds like it lost half its volume today, it plays clear but I have to crank the volume to the max to get even close to normal listening level. That's connected to a completely different NAD integrated amp I bought a few weeks ago.

 

[MCM_Fan]

I really don't have anything to measure arm weight on the record, but I do know that its just about zero unless I stack three records and add four or five quarters to the tone arm at the cartridge. The arm is sort of S shaped and don't look bent, its identical to the one on the second 6502.

I went ahead and removed the cue bar completely, with it out of there, the arm follows and tracks fine, but the distortion is still there even with the new cartridge. I did an ohm test of the rca plugs before, all are ok, no resistance, no shorts all the way from the cartridge to the rca plugs.

The cue bar has rubber on the top, I can see where the rubber is worn where the arm has been dragging on it for a long time. I've got the counter weight all the way forward right now, for the least counterweight possible. Putting more weight on the arm still makes it sound better but its no where near acceptable.It has to be a bad new cartridge making the garbled sound, plus what ever ails the arm itself. I'm about ready to grab this thing by the cord and toss it out the window.

To top it all off, the Beogram I bought sounds like it lost half its volume today, it plays clear but I have to crank the volume to the max to get even close to normal listening level. That's connected to a completely different NAD integrated amp I bought a few weeks ago.

I would not completely dismiss improper VTF or antiskate for the distortion and low levels you are hearing. You really need to start by properly setting up your turntable and going forward from there. You should not have to stack records or add four of five quarters to the headshell to get it to track properly. To me, those are symptoms of a wildly out of spec set up. Watch some YouTube videos on how to balance a tonearm, set VTF and antiskate and align a cartridge. It may be a set up issue and not an equipment issue. Right now, you have too many variables. Even if proper step doesn't fix your problems, it will at least eliminate some of the variables from the equation and help you to start making forward progress on root causing the issue. Right now, you are just kind of shooting in the dark hoping to hit something.

 

[gotitforfree]

It looks to me like the cue bar is the cause of the lack of pressure on the record, with it in place, the needle barely touches the record. Without it, its able to drop down. The cartridge appears level with the record. The needle don't seem to make any sound until its pushed almost flat up into the cartridge. That's A LOT of pressure. Just touching the record doesn't let it track, even with the counter weight removed. The Beogram I just bought barely touches the record and it tracks fine. It feels like something is bottomed out in the tone arm, even without the cue bar in place. With the tone arm down, its hard to move sideways. (I removed the platter and cartridge, with the cue bar out, and the arm just hanging downward with its own weight, I have to push pretty hard to make it move sideways. When I lift it up a bit, it swings freely. Using a gram scale that I use for reloading I get 2.7 grams at the needle with the counter weight all the way forward and the arm will track but not play without distortion on a stack of records, with one record, the scale reads 1.9 grams and wont track. It will sit in the same groove over and over again until I move it.

 

[Nashou66]

Do you have another Cartridge to try on it? Pushing that hard to make any sound means you might have broke the diamond off.

Can you take a pic of the cartridge stylus up close if possible?

Nashou

 

[MCM_Fan]

It looks to me like the cue bar is the cause of the lack of pressure on the record, with it in place, the needle barely touches the record. Without it, its able to drop down. The cartridge appears level with the record. The needle don't seem to make any sound until its pushed almost flat up into the cartridge. That's A LOT of pressure. Just touching the record doesn't let it track, even with the counter weight removed. The Beogram I just bought barely touches the record and it tracks fine. It feels like something is bottomed out in the tone arm, even without the cue bar in place. With the tone arm down, its hard to move sideways. (I removed the platter and cartridge, with the cue bar out, and the arm just hanging downward with its own weight, I have to push pretty hard to make it move sideways. When I lift it up a bit, it swings freely. Using a gram scale that I use for reloading I get 2.7 grams at the needle with the counter weight all the way forward and the arm will track but not play without distortion on a stack of records, with one record, the scale reads 1.9 grams and wont track. It will sit in the same groove over and over again until I move it.

You should not have to remove the counterweight, you should not have to add 4 or 5 quarters on top of the headshell, you should not have to stack three records, you should not have to do any of these things. These are all extreme measures that do nothing to solve your actual problem. Before you can hope to root cause your problem you need to make sure your turntable is properly set up. Until then, you are just spinning your wheels and chasing false problems.

 

[gotitforfree]

I don't see what else I can do to 'set up' this thing. No amount of weight adjustment will fix the issue, I can move that counter weight in either extreme and it won't fix the arm resistance or travel issue.
The platter height is fixed by the spindle, the arm is fixed by the mounting surface. I took the whole arm off an swapped on the one from the other 6502, it does the same thing.
The cartridge and stylus were new two weeks ago, they are identical to the original. I have a spare stylus from the parts machine and the old one from the original cartridge.
If it weren't impossible, knowing nothing about turntables, I'd say the tone arm mount is too tall or the platter is too low. With the cue removed, with either arm installed, with the stylus removed, I can only get the arm about 1/4 inch from the surface of the record. It physically can't go any lower. Its not bent, its S shaped, and both arms are identical.
On the Beogram, when the tone arm is off the record, if the cue didn't catch it, it would go down beyond the record. That's not possible on this MCS. The tone arm is being held up by mechanical limitations in the way its made. With the cue bar in place, its about 3/8" above the record at the lowest screw setting with the lever down. The cartridge is an AT91 I got off eBay new.
I did try the old cartridge in an old RCA TT I have here and it works fine. Since the old cartridge works on another TT, I swapped it back for now. The new cartridge will only work with the old needle.
The diamond is on the needle, I tried taking a close up pic but I can't get a clear pic to post of something that small with my phone's camera, (only a 1.3 megapixel cam).
If you look at the pic above, the tone arm pivot area has an orbital shape around the post, the post is hitting the ring before the cartridge drops low enough to hit the record. The arm position looks about the same as the one in the above pic. Also, if it needs to be said, the platter has the original rubber mat on it.
The part that gets me is that the last owner was supposedly using this TT before getting evicted or moving out. The parts TT supposedly needed only a stylus, but so far that's the one thing that I've found that works off that TT.