My Technics SL1210mk2 problems, channel imbalance

[Bwaze]

My first post here, apart from introduction. I'll try to make this brief, but I think my turntable is really messed up. By me. :scratch:

So, I wanted to know what turntable works like. :) I never had one, and I really like the artwork on the album covers, so I thought to buy something cheap and play with it. I really don't have any friends that are into hi-fi, so I'm really struggling a bit with the completely unfamiliar territory.

Technics SL-1200 MkII came highly recommended many times as a starting turntable - easily available used, and easy to set up for a beginner (allegedly). So I ordered one that seller described as "used only at home for music playback".

For 160 EUR (around £130) I got a pretty battle-worn DJ abused turntable without lid, without headshell, with non functioning Ortofon Concorde Pro S cartridge... Also, looks like whole turntable was dropped at least once - platter was wobbling by about 1 mm when spinning and arm was bent a bit in the rear end, and arm bearings were affected too.

:steam: Seller of course didn't answer any of my subsequent mails or phone calls...

So I ordered new spindle, new Technics SL-1200 M5G arm (recommended as it has better wiring than stock) and a lid, Audio Technica 95E cartridge and Sumiko HS12 headshell. Paid more than the used turntable was worth, but I figured I'll have pretty much a new turntable after I change all the parts that can wear off.

Disassembling the Technics, cleaning it and replacing the spindle / bearing was easy, and to my relief platter now turns completely level. But I struggled a lot with the arm...

M5G arm does fit on the MK II, but apparently the two screws that fix it to the base are waaay too long - I managed to damage the "horizontal weight control knob". Removed it, since I don't really need it, I think. I really did a botched job on replacing the RCA wires, I replaced them with the Belkin PureAV coax cables, soldered them directly to the thin tonearm wires.

I set up the cartridge with the Baerwald protractor from VinylEngine, printed it to correct scale and carefully aligned so that the needle follows the arc completely and is square to the grid at two points. Cartridge is quite forward on the Sumiko headshell, and I have additional weight attached to balance the tonearm.

I set up the stylus pressure to a bit less than maximum recommended for AT95E, 2,4g. I set the atiskating less than that, since I think the dial is a bit wrong.

I used the new Hi-Fi News Test LP. I connected the amp rec output to the computer line in so I can record and analyse the results in Audacity (free audio software).

Anyway, the problems:


- arm has no 0 antiskating position - even at 0 there is a little bit of antiskating that move the arm towards armrest when arm is balanced, and is stronger towards the centre of platter. Turntable is level, checked with several levels. I might have moved the antiskating knob accidentaly when reassembling arm base - I disassembled it completely to clean it and relube the VTA mechanism. I don't think the antiskating mechanism is damaged otherwise.

- I can't get the right channel to play properly. It lacks high tones and is quieter than the left by a lot. At first I tried to fix it by changing antiskate and azimuth, but antiskate had very little influence on that, and I ended with A LOT of azimuth to get the even loudness of test tone from Hi-Fi News test LP tracks. I later found out that this strong azimuth only balanced the 300 Hz tone, the rest is still way too low on the right.

Anyone else used computer to analyse the output of their turntable, or are you all setting it up by ear?

That's the screenshot of completely balanced 300 Hz test tone from Hi-Fi News test LP. I got it to within 1 dB difference left to right. Waveform representation with frequency analysis.
http://i84.photobucket.com/albums/k26/Bwaze/Technics%20SL-1210%20MkII/Balancetone300Hz.jpg

But I quickly found out on other tones and music that that didn't work. This is the spectrum representation of sound, and right track is much quieter, especially in the high frequencies.
http://i84.photobucket.com/albums/k26/Bwaze/Technics%20SL-1210%20MkII/OperationMindcrimeimbalance.jpg

So, any ideas what could be wrong here? Bad soldering of tonearm wires to interconnects? Incorrect antiskating setting? :scratch:

[Artifolk]

UMMM... now i know why i don't want to touch mine.:doh:

Pics of the cable joints might help and it looks like your using a Digital cable (no Earth lead), I've no idea whether this would make a difference, I'd have thought Analogue cables built for the purpose would have been a better choice.

Anyway I'll leave this to the Experts here.

[Stratmangler]

The problem might be your Audio Technica 95E.
Production faults are not unknown.

[Bwaze]

The problem might be your Audio Technica 95E.
Production faults are not unknown.

That would make finding the culprit even more difficult! :doh:

I didn't take any pictures of cable joints, but it's messy in there. Belkin PureAV digital cable was what I had at hand, and I read that they have the right capacitance for a phono cable. Their construction is similar to a coaxial cable. A thick solid core, teflon insulation, mylar foil and woven copper "shield", and there was even a sepparate wire between mylar shield and woven copper stuff... It says "quad shielded" on the cable, but as far as I could see all the conductive pieces apart from the centre core were connected on both ends to the - (outer ring of RCA). So what's the shielding here? Anyway, I soldered all the - stuff together.

I now double-checked the connection from headshell connectors to the RCA connectors with multimeter, and haven't found anything wrong - minimum resistance and no shorting from one channel to the other, so I really can't see how the cabling could be at fault here to such extent.

[Greg2010]

Perhaps you could try swapping the headshell leads over, take another measurement. If the bias shifts to the other channel it's likely the cart, if not the fault may lie further down the chain.

Regards
Greg

[Bwaze]

Tried to change the wiring to the cartridge, and the left channel remained louder.

Then I also tried swapping the RCAs of the cable to computer (channels switched, so it's not computer audio card bias) and RCAs from turntable to amplifier (channels switched, so it's not a bias in faulty phono preamp).

So it has to be something between the cartridge and amplifier. Cable. Elementary, my dear Greg2010. But I would never have thought about it...

Thank you for the help! Tomorrow I'll disassemble the arm base again and resolder the wires. And if that doesn't help I'll try the old turtable interconets, can't be worse than that. I just hope I haven't damaged the wires up in the tonearm somehow... But even that is not unrepairable.

It's really a very learning experience, getting a broken turntable. :lol:

[Bwaze]

Thanks to Greg2010 the turntable is fixed!

Disassembled, unsoldered right channel wires and cleaned them, resoldered, put the bloody thing together again, set the arm, and it works perfectly!

:eek:

I'm now playing with Hi-Fi News test LP again, but the Queensryhe's "Operation: Mindcrime" souded as it should!

I still have tons of questions, being beginner that I am... Like:

- should I really not use any solvents in the same room the cartridge is? Is the suspension really that sensitive? Does alcohol count as a solvent? :cool::mental:

- is it OK to put the needle on the stopped platter and hit start, or is it more advisable to do everything with the spinning platter? I read somewhere that "cueing with stopped platter on SL 1200 saves wear on the needle and vinyl"

- my VTF is set to 2.4, a bit less than maximum recommended 2.5 g for now. I double checked it with cheap Chinese 0.01g scale. When I set the antiskating to such a high force, I'm struggling a bit with the cueing on the inner tracks - arm slips to the outside when I lower the cueing lever. Is that normal?

Thank again for all the help, everyone!

[Greg2010]

Excellent news Bwaze, cant do christmas without a vinyl fix :)

Vtf I alter till I get the best sound, antiskate I'd start .5 less than your vtf and alter by ear: so at 2.5g vtf you'd start somewhere around 2 or maybe a bit less on antiskate setting but I'm no expert. I'm sure there will be a more scientific approach but it works for me.


Regards
Greg

[KCD]

arm slips to the outside when I lower the cueing lever. Is that normal?

No, that shouldn't happen.

It is also possible that the tonearm wires are causing the arm to pull back.

Once the table is level you can remove the headshell and check the tonearm by allowing it to drift towards the spindle. Turning the antiskate knob will make the arm return to the area of the rest if everything is OK with the arm. If the arm will not move toward the spindle smoothly or if the antiskate fails to bring it back towards the arm rest something is binding but it sounds like the wires are binding on something or you reassemble the antiskate mechanism a little off.

KC

[Bwaze]

Well, I guess I managed to assemble the antiskating mechanism a bit off - at 0 it has just a tiny bit of force towards the armrest. I don't think the wires are pulling on the arm, I can pull them a bit out where they enter from the arm to the base with a toothpick, and there is slack. I guess the dial is a bit wrong now, but shouldn't be too much of a problem, I'll just dial a bit less.

The cartridge tracks all the test tracks on Hi-Fi News Test LP without problem, except for the last one on Side 1 (Bias setting, 300Hz tone, L + R, +18 dB) - it's described as a real torture track. I can get it to track it by increasing VTF to 2.7 and increasing antiskating, but then the antiskating really messes with the cueing, so I guess it's not really that important to track that one.

Cartidge / arm resonance test show strong resonance at 9 Hz for lateral or horizontal tracking, but for vertical there is some warble in the tone at 20 Hz and then again more at 10 Hz, but both are subtle.


And there's one more thing that's bugging me: channel balance, again. :)

Everything I play now is well balanced, except for the track 5, side 2 of Hi-Fi News Test LP - cartridge alignment, 300 Hz tone, +6dB, left and right channel are out of phase. It's meant to be self-cancelling if you switch the amplifier to mono if the channels are identical, and is used for setting of cartridge azimuth.

My amp doesn't have the mono switch, but I can record the track in Audacity and merge stereo track to mono. Well, If I try to set azimuth by this track, the rest of them aren't balanced, music isn't balanced, and headshell ends up non parallel to the record surface. Every other track on this LP or any other I have tried is balanced if I set the track parallel to the LP surface.

I noticed that bias setting tracks with 300 Hz tone have the same phase on both channels, so if I record that, invert phase of one channel and merge tracks to mono, I can set the azimuth by that very precisely. And the music now sounds balanced.

But I have no idea why only the track that is meant to be used for balancing isn't balanced then. :scratch:

Some pictures:

Track 5, side 2 of Hi-Fi News Test LP - cartridge alignment, 300 Hz tone, +6dB. Right channel is about 20% quieter.
http://i84.photobucket.com/albums/k26/Bwaze/Technics%20SL-1210%20MkII/25Cartridgealignmentunbalanced.jpg

Track 1, side 2 of Hi-Fi News Test LP - tracking ability test, 300 Hz tone. Tone is completely in phase, I inverted phase of one channel:
http://i84.photobucket.com/albums/k26/Bwaze/Technics%20SL-1210%20MkII/21Trackingabilitytest300Hz.jpg

Same track, channels merged to mono - channels almost completely cancel each other out.
http://i84.photobucket.com/albums/k26/Bwaze/Technics%20SL-1210%20MkII/21Trackingabilitytest300Hzmerged.jpg

Well, I guess the test LP isn't perfect - I've read now a lot of criticisms. Some tried to use Track 7, side 2 - Full range frequency system check to measure frequency response of their turntable. They found out that the test tone was produced by someone hand turning a knob on oscilloscope, hence the uneven curve:

http://i84.photobucket.com/albums/k26/Bwaze/Technics%20SL-1210%20MkII/27Frequencysystemcheck.jpg

:lol: