60mm hole. The mounting plate on the back of the armboard will be 69mm or 79mm depending which version.
Vintage DD turntables. Are we living dangerously?
I have just acquired a 32 year old JVC/Victor TT-101 DD turntable after having its lesser brother, the TT-81 for the last year.
TT-101
This is one of the great DD designs made at a time when the giant Japanese electronics companies like Technics, Denon, JVC/Victor and Pioneer could pour millions of dollars into 'flagship' models to 'enhance' their lower range models which often sold in the millions.
Because of their complexity however.......if they malfunction.....parts are 'unobtanium'....and they often cannot be repaired.
TT-101
This is one of the great DD designs made at a time when the giant Japanese electronics companies like Technics, Denon, JVC/Victor and Pioneer could pour millions of dollars into 'flagship' models to 'enhance' their lower range models which often sold in the millions.
Because of their complexity however.......if they malfunction.....parts are 'unobtanium'....and they often cannot be repaired.
Showing 48 responses by jpjones3318
The MN6042 is used in the MK2 versions of the SL-1300/1400/1500/150, the SP-15, SP-10 MK3, and SP-02. Lewm: not millions by any stretch. The nominal frequency through the pitch chip is 262.080KHz. This is also where I'm seeing ~8Hz variation across the three samples I measured. The output of the pitch chip is delivered to the DN860, which divides by 1/8, then 1/54 for 33RPM, and then 1/12 to the AN660 chip. The "quartz locked" frequency for 33RPM is 50.5555Hz, which is the frequency the AN660 uses to develop the reference and error control lines to the motor drive. For perspective, the AN660 sees 50.5555Hz for 33RPM at 0.0% pitch, and 50.6061Hz for 33RPM +0.1% pitch from 262.080KHz. 262.074KHz is 50.5543Hz to the AN660, and 262.081KHz is 50.5557Hz at 0.0%. Theoretically instability in the reference frequency should manifest as a voltage instability in the reference line to the motor drive. We'd then need to determine how the motor control would react to the degree of variation induced. My theory is this would work in concert with the offset voltage adjustment; tighter control of the reference voltage would allow the drive to be more critically damped. When I get the next revision of boards in I'll put the motor on the bench and measure through the entire system. I haven't managed to find a test record anywhere close to the quality needed to reliably measure flutter below 0.02% JIS, so my conclusion on whether the increased stability of my chip replacement equates to anything of note at the platter may be based upon a bit of conjecture. Worst case, it's designed to be a modern, resilient drop-in replacement for any circuit that uses an MN6042. Best case, we've made things a bit better in a meaningful way. I do plan on making it available, as I'd love to have a shot at recouping some of the R&D costs. It's amazing how fast things add up. As the largest component on the board is a 4x4mm 20 pin package with no leads, I wouldn't offer it as a kit. Please PM for info. JP |
rower 01-22-2016 1:19pm Someone like Bill T would have better first-hand knowledge, but in my research nearly all the examples I could find that had DN860 or AN660 failures had tell-tale signs of prior work that didn't appear very impressive. I just didn't see any evidence of "spontaneous" failures for any of the other ICs like you do for the MN6042. The motor drive IC, AN640G, is still plentiful, but those don't seem to ever fail. AN660s and DN860s still show on eBay once in a great while as have a couple MN6042 recently, but they're becoming few and far between unless you strip a lower model 'table. Not as easy as the MN6042, but I think something could be fairly easily made to replace the DN860. That's not to say I think it'd be worthwhile though. I've a bit over two months and well north of $1000 in to the MN6042 replacement. |
lewm If your stock chip exhibits the same clock fluctuation as all the samples I've measured, it is an improvement. |
lewm Let me add some color to that - my philosophy is if it’s not less than optimal, not prone to known reliability issues, etc. then don’t "fix" it. My MN6042 upgrade wasn’t borne out of the need to replace failed parts, but due to the fact that every stock part I measured performed poorly. chakster I bought one new six months ago. I think it was somewhere around the 23rd page of a Google search I found a little online store in Italy that actually had one in stock. Sadly, their last one. |
lewm Very kind of you Lew, but it was offered to you, so if you want it you should get it. I hope you don’t mind - I took the liberty of sending your e-mail address to acman3. pryso I recommend replacing the three motor drive caps with the next higher voltage rating. Those three take the most abuse in the chassis. And, of course, if you recap it you’ll need to readjust the PLL to ensure it’s running right. Truthfully, most of them will be out of adjustment after 30+ years regardless. |
lewm If you go to a show where Pass Labs have their source setup, you'll likely see a MKII with an ~8kg stainless steel platter. My understanding is their 'tables have been setup this way for years without issue. Stainless platters for the MKII show up on Yahoo every once in a while. I had one (a platter) here for a bit on one of my MKII. Takes a little longer to start and stop, but I didn't notice any ill effects. I didn't measure any circuit parameters while running it - having a MK3, it was doubtful I'd even keep a MKII around. W&F was about the same as the stock platter. You'll see stainless platters show up on Yahoo every once in a while. I'd monitor the thrust pad a bit more often. |
lewm Okay, but I’m more than rusty on root locus and complex conjugates. :) My very hasty research this morning indicates rotational mass isn’t going to have an affect on the PLL if the drive is compensated. It may not have a meaningful effect regardless. Increasing the rotational mass means a given correction to be performed in the same amount of time will require more energy. If not the reaction time will be slow. Note the sync position timing for the MK2A and MK3 are the same, yet the MK3 platter is just over 3x heavier. Most of that mass is inboard but it’s still a significant difference. I think this is one of the reasons these DDs can be so polarizing - there’s no way to tell how different techs are calibrating them without measuring one first-hand, thusly no way to really know that they’re performing the same. A MK3 can be dialed back so far the motor will actually overshoot and bounce off phase lock 2-3 times before settling, or set over-critically such that the drive MOSFETs will self-destruct in seconds. I’ve mentioned I’ve seen these running in belt-drive emulation mode before - that’s wasn't a joke. I haven’t measured a MK3 or MK2A with additional platter mass. On the MKII the W&F measurements were negligible, but I don’t think that’s a spectacular measurement for how a drive system reacts to real-world conditions anyway; more of a steady-state baseline. The TT-101 at a block level is really no different than an SP-10 aside from what it takes to drive their coreless motor, so I wouldn’t expect a little extra mass is going to have a broad affect on what you hear. The motor will not be as critically controlled, though depending on the mass that may be negligible, or actually preferable. |
SFTG172-01 was for the MK2A and MK3. The latest equivalent is RGS0010A which is the thicker mat that was used on the SL-1200 MK3, MK4. I've both here, and aside from the part number I can't see any difference. The MKII used SFTG102-01: http://fidelisanalog.com/wp-content/uploads/sites/3/2016/03/IMG_1031.jpg RGS0008 is the thinner version of the RGS0010A/SFTG172-01. The SP-15 used SFTG015-01: http://www.vinylengine.com/turntable_forum/viewtopic.php?f=18&t=71002#p568735 |
norm, Are you certain the Elgar unit is working correctly? I see that it's advertised as having sine output. I'd try a simple step-down as a sanity-check, à la https://amzn.com/B000WMK6QY. According to the literature the transformer in the 101 is a potted toroid. If that's vibrating, something is VERY wrong. JP |
Hi Halcro, The top on this one isn't painted like most - it's brushed and anodized. The discoloration you see is what the raw casting looks like. http://fidelisanalog.com/wp-content/uploads/sites/3/2016/11/IMG_2102.jpg |
Hi Halcro, Not NOS, but rather good shape considering. The main bearing in this one is in spectacular shape - extraordinarily smooth. Yes, we're talking about the same area. The exposed bit is brushed, and the inside bit is unprepped. The full piece is anodized and therefore protected. On the other two TT-101 I resurrected that area was painted. |
Hi Lew, I don't have any pictures of yours that show the finish, but I thought it was painted. I've had a couple TT-101 through here since yours. This one seemed like a nice candidate for refurb. I'm not sure what its disposition will be as I've a PS-X9, L-07D, and a second MK3 in the refurb queue for my personal collection. I hope you had fun in NYC. It would've been fun to meet you regardless, though I was at our house in CT over the holiday. I'm working on some other improvements to the MK3 controller, so waiting may be in your favor :) |
I'd say the A505 is a near second, but it may be a wash; one has better bearings, the other an adjustable counterweight. http://fidelisanalog.com/img_0707/ |
This is the product launch brochure for the SL-1000 MK3D: http://fidelisanalog.com/2016/10/08/technics-new-products-of-10-1982-2/ And scans of the 3x5 glossies that came with it. Click and click again for the high res version: http://fidelisanalog.com/2016/10/08/technics-sl-1000mk3d/ |
I currently have in my collection a few SP-10MK3, an NOS SP-10MK2A, DP-100, L-07D, PS-X9, TX-1000, TT-101, and an SL-1200 GAE and MK4. Oh, and a TD-224, just because I like the clockwork mechanics. Most of them are in the refurb queue, and as such I haven't been able to hear them. Some aren't complete; I'm looking for a MAX-237 for the TX-1000. Actually, that's the only one that isn't complete. I don't find the TT-101 electronics all that complicated, but the calibration procedures are a bit complex and the service manual, as they all do, gets some stuff wrong, and leaves some stuff out. The main board is beyond fragile which makes them a royal pain to work on. I've lost money on the few I've resurrected, and now won't even consider touching one for less than $1500. On the last one I had to repair a broken coil in the motor, and repair the main bearing, though that was inflicted damage. Professionally I was a technology consultant up until a month ago, when I went full-time with my top customer. Since then my free time has been nearly non-existintent, and what little I've had I've spent on my own selfish pursuits. Plus it's summer, and I'd rather be on the lake on my wakeboard! :) |
Hi Misha, Never had my hands on an SL-10 or 15, though I certainly wouldn't mind playing with one. I’ve limited my collection, for the most part, to the absolute statement ’tables from the Japanese manufacturers, though I may sneak an EMT in the mix. These days I play with other ’tables by repairing them, if I’ve the time. |
Hi Misha, The two seconds for the display to change is normal. If you put it in run mode you can watch it count up. It does the same in hold mode, though only updates the display at the end of the cycle - every 1.8s IIRC. If it's stopping as Lew described you've a situation where too much current is being supplied to the motor. Time won't fix this; it's likely there's a bad connection on the board. |
Three hall elements = hall effect sensors. They control the commutation. If the display blanks and the motor coasts to a stop, the over-current protection circuit is being tripped. This is a picture of the sensors - the windings are on the other side of the board. This should show enough detail that you can trace the wires connected to the sensors to allow you to test them without opening the motor. http://fidelisanalog.com/wp-content/uploads/sites/3/2017/09/IMG_1634.jpg |
Here's the other side of the board: http://fidelisanalog.com/wp-content/uploads/sites/3/2017/09/IMG_1633.jpg |
Conversely I've been in to a lot of units for various reasons that appeared to be working fine that weren't. The good DD circuits are great at compensating for all kinds of ills. I've seen grossly miss-calibrated drives where the motor was fighting itself, and the owners heard no audible ill-effects. Every SP-10MKII/2A/3 I've been in has had physically and electrically leaking caps. The ones that would still spin seemed to spin fine, even though upon measurement they were clearly unhealthy. Some fare better, some worse. The bottom line for me when doing a refurb is that the average life of electrolytics is well established, testing each one isn't worth the time, and there's no way to predict when a cap may become marginal or flat-out fail. Failed or failing caps don't always physically leak or vent. I've never been an advocate of shotgun parts replacements in place of fault-finding and repair, and do caution amateurs that doing so can cause issues as they may indeed cause other failures in the process. Once in a great while I do end up eating some hours when replacing known problematic parts due to other failures. It's rare and I don't charge for that time. This isn't my day job, and my primary motivators are to ensure pieces leave performing at least to factory new levels, and to do everything within reason to ensure I never see a unit come back. |
Sadly, Lew, a fair number of serviced units aren't in calibration either. Freeze spray helps, as does not being afraid to twist the board back and forth a good 30 degrees or so. This will likely cause more joint issues, but they were about to become issues anyway. This is why, when I was working on such things, I charged so much for the TT-101. It takes a lot of time when your goal is to try to ensure that particular unit never sees your bench again. BTW, I think the TT-101 service manual is excellent - far better than the SP-10MKII. Granted, there are no troubleshooting flow charts, but they do go through great pains to explain how the circuit works. The downside is you have to take the time to actually understand it. @chakster, you likely have a fractured joint or trace on your board that is opening after the unit warms up. The self-shutdown is due to an over-current condition in one or more of the drive amps. This protection is there to prevent things from burning up should the motor be stalled. |
@best-groove, if one uses threaded rod and a couple washers and nuts in each of the three mounting holes, you can lift the entire unit up a good 12", leaving room directly underneath. This is why the cables harnesses are so long - so the main board can be turned over with component side accessible, laying on the work surface below the suspended unit. Most DD's can be worked on this way. |
There's simply no way the calibration survived that. Barely nudging those pots drastically affects the circuit, and in the drive circuit they all interact. The mechanically tolerance affects the setting, so aligning witness marks won't work. Best rule of thumb on quartz/PLL DD circuits: don't touch the pots unless you can recalibrate yourself, or have it done. |
Platter continuing to rotate after you press the stop button is associated with calibration. A well calibrated turntable should stop pretty much dead when you press the stop button. But my TT101, which was calibrated by JP and works wonderfully, also moves an inch or two more after I press the stop button with an LP on the platter and a heavier than normal turntable mat (SAEC SS300) . I decided not to worry about this, because of the extra mass. If JP is anywhere around, perhaps he will comment. The brake is calibrated with the mass of the mat and standard LP on the platter. If the mass of the platter is higher than that it'll move a bit further after pressing stop. |