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12_8_2010

Taking it apart completely:

Recently another TD160C came my way.  It had some good features to it but unfortunately it also had a bent armtube on its TP16 tonearm. In order to replace the armtube it is necessary to disassemble the tonearm completely. At least this way we get to see all of the parts inside.

DSC_5576.jpg (217955 bytes) Here's an exploded view.  It does kind of look like an explosion took place..;-)

 DSC_5577.jpg (291098 bytes) DSC_5578.jpg (281948 bytes) 

DSC_5579.jpg (231777 bytes) DSC_5580.jpg (246557 bytes) The lower horizontal pivot bearing.  Cone and cup variety.  Cone has a ball race.  The cup is pressed into the lower body barrel and consists of a circular array of steel bearing balls.  The cone can be seen as the conical ball race mounted on the shaft in the photo at left.

DSC_5581.jpg (170656 bytes)  Another view of the lower horizontal bearing cone.

DSC_5582.jpg (162864 bytes) 

DSC_5583.jpg (188832 bytes) one of the two vertical pivot bearings.  Cone and cup design.  The cup features 5 steel bearing balls in a race. Adjustment is by fine pitch threads on the cup and in the gimbal housing.

DSC_5584.jpg (185946 bytes) The vertical pivot cones are part of the same shaft that is pressed into the cast housing of the armtube. 

DSC_5615.jpg (165749 bytes)

DSC_5614.jpg (149556 bytes) The upper horizontal pivot bearing cone.  Showing some dust particles clinging to its bearing race.

 

The next stage is to replace the bent armtube with that of another TP16.

DSC_5596.jpg (244752 bytes) The replacement arm tube prior to assembly of the tonearm wires and coupler joint.

 

DSC_5597.jpg (263608 bytes)

DSC_5598.jpg (161039 bytes)

DSC_5599.jpg (201865 bytes)

DSC_5600.jpg (232059 bytes)

DSC_5601.jpg (219544 bytes) There.  The replacement arm tube with tonearm wires and coupler joint assembled.  The old damaged arm tube can be seen above the new one.

Further assembly details.

DSC_5602.jpg (308488 bytes) 

DSC_5603.jpg (152426 bytes)

DSC_5604.jpg (192099 bytes) The vertical pivot brg cups have been flushed out with acetone to remove any dust/debris/residue.

DSC_5606.jpg (258629 bytes) Vertical pivots installed.  Adjustment is preliminary.  Each cup screws in equal distance to fully engage the cones and place the arm tube in the center of the gimbal.  

DSC_5610.jpg (172891 bytes)

DSC_5611.jpg (157258 bytes) The vtf adjuster wheel requires the spring and detent ball to be assembled prior to fitting.

DSC_5612.jpg (145242 bytes)  Spring and detent ball in their socket.

DSC_5613.jpg (140484 bytes) VTF adjuster wheel in place.  Note the very thin, almost invisible, cord that slots into the pocket within the wheel.  As the wheel is rotated, the cord tensions another spring within a tube above the counterweight.  It is a little tricky to install this cord correctly.  Sorry, no photos for this detail but if you have made it this far, I'm confident you'll figure it out as I did.

DSC_5620.jpg (134064 bytes) VTF wheel with the upper horizontal bearing cone assembled.  The cone looked good under magnification.  Was cleaned in acetone.  Wiped dry with soft cloth and mounted.

DSC_5621.jpg (224087 bytes)anti-skate magnet.

DSC_5622.jpg (197599 bytes) anti-skate magnet underneath.  This is not a particularly strong magnet.  A refrigerator magnet exerts greater energy than this one.  It fits up beneath the inner gimbal and is held in place by the steel tube that holds the lower horizontal pivot bearing cone.  The steel tube threads into the  bottom of the  inner gimbal and clamps the magnet solidly.

DSC_5623.jpg (209399 bytes) The inner gimbal being assembled into the outer frame.  The tube extending out the frame threads solid into the bottom of the inner gimbal.  The tube contains the lower horizontal bearing cone.  The aluminum housing, just to the side, contains the lower horizontal bearing cup. The steel tube fits down into housing to engage the bearing cup.  Housing screws into bottom of the outer gimbal frame.

DSC_5624.jpg (218830 bytes) With the housing partially assembled, but the upper horizontal bearing cup still not in place.

DSC_5625.jpg (209572 bytes)  With the upper horizontal bearing cup assembled.  It threads into the outer gimbal frame to engage the upper horizontal pivot.  Preliminary adjustment of the horizontal pivot bearings is to gingerly thread the upper cup until solid contact is made against the cone.  Both upper and lower horizontal pivot bearing tension is adjusted by the upper cup.  Free movement of the armtube is retained while the cups and cones are adjusted rather solidly.  When finished, there is a decorative dust cap which snaps into place above this upper bearing cup adjuster.  

DSC_5627.jpg (118529 bytes)  Preliminary check to view the partially assembled tonearm.

DSC_5628.jpg (90207 bytes)  Another view.

 

Testing the results.

A spare cartridge is mounted.  A trusty Grado Prestige Black.  

Alignment notes:The Thorens headshell jig is used to set overhang.  Every TD160C came equipped with several accessories including the headshell alignment jig.  Most, unfortunately, have been lost by their owners.  I managed to keep mine. If you lack the headshell jig,  overhang alignment for the TP16 is per Stevenson.  So get a Stevensen based 2-point alignment protractor. Although it is sometimes possible to use a Baerwald protractor, (on this tonearm), but only if the distance between stylus and mounting holes on the cartridge you've got fitted is not too long.  (Baerwald overhang lengths tend to be longer than Stevenson overhang lengths) Azimuth is set using a mirror and the headshell jig.  VTA is set by leveling the arm tube to the platter.  Adjustments made at the base mount using the two set screws to release /adjust height/ re-fasten.  VTF is set by first balancing the arm to float slightly above record level with vtf ring set to zero, then adjusting the vtf ring to 2.0 grams of downforce.  Antiskate was initially set to 2.0 grams, but later re-set during the hfnrr test record session to improve the scores on the bias tracks.

For more detailed information regarding tonearm and cartridge alignments see this link: here

For more detailed information on using the TP60 headshell alignment jig link: here

HFNRR Test Record session (HFN 001)

side 1

  1. R/L was swapped, swapped again to correct
  2. phase = ok
  3. bal = ok
  4. bal - L = ok
  5. bal - R = ok
  6. clean
  7. clean
  8. clean
  9. buzz left

note tracks 6 through 9 (Bias tracks) are sometimes referred to as the 'torture tracks' because they measure tracking ability by providing a 300 hz tone with increasing decible levels at each succeeding track.  A clean pass means that the arm/cartridge was able to track through the band without buzzing at either channel.    Tracks 8 and 9 are generally regarded as overkill in that there is likely no Lp track that will duplicate this level of amplitude.  However these tracks are useful as a repeatable measure of how well a given arm and cartridge can negotiate them.  In this case it appears that this relatively inexpensive tonearm and cartridge has scored very well. Very few tonearms/cartridges can pass cleanly through track 9.  .......This indicates that the cleaning and adjustments made to the pivot bearings was successful. 

side 2

  1. trackability = clean
  2. lateral arm/cart resonance test  = 9 - 10 hz
  3. vertical arm/cart resonance test = 10-11 hz
  4. trackability = clean
  5. equal by ear (azimuth check)
  6. unmodulated groove to evaluate residual system noise = quiet
  7. trackability = clean

Listening check

I put on Paul Simon, There Goes Rhymin' Simon.  This Lp I am very familiar with and use it as a check for VTA setting.  The limit here is the low priced Grado Black.  This is their lowest priced offering.  Even so, it re-produced the music on this Lp cleanly and with good ambiance.  I have to admit, however, that this tonearm deserves a much better cartridge than the Grado Black.  In the past I have listened to other TP16 (mk1) tonearms using much higher quality moving magnet cartridges to very good effect.  

Conclusions:

The cleaning and adjustments made to the pivot bearings resulted in a tonearm that tracks difficult grooves very well.  Frankly, I am surprised that it scored as well as it did on the hfnrr test record 'torture tracks'.  All in all.....a success.  Given this level of encouragement, it seems logical to consider the possibility of upgrading the standard tonearm wires of this tonearm to a higher quality wire.  Silver perhaps.  And then the RCA cables could be replaced with a high quality RCA jack plate with nice gold plate RCA jacks to accept the IC of your choice. 

Additionally, I wonder how well this tonearm would handle low compliance MC cartridges known to energize armtubes with needle talk.  Would a Uwe bodied DL103R tend to rattle the pivot bearings on this tonearm, or would they handle the energy and allow the DL103R to sound like itself?

Photos by user510 except as noted.