Broken Leads
A Schröder owner reached out to us for help with his CB tonearm.
He reported tracking anomalies (skipping backward), but when we received the arm, no signal was passing through it.
First things first ... get sound.
A quick continuity check pointed us in the right direction.
We opened the strain-relief collar, and found 3 of the four signal leads were broken. The first step was clear - a rewire.
Click on all photos for an expanded view.
Schröder Background
It's no secret that I love these tonearms, but they're not for everyone. Out of 10 inquiries for a CB, I sense that a 4Point is more suitable to perhaps 7 of these individuals. I expound on this in the "best tonearm" blog post.
Our custom arm rests make Schröders more user friendly - especially in light of the ultra low friction bearings. The adjustment features still require a fairly experienced hand to navigate. I love these arms, but they're not for everyone.
The Schröder user is rewarded with sonics that rival cost no object tonearms. If you know what a double bass, cello, oboe or clarinet sounds like in real life, no other current production arm will do in my experience. If compared to the world of vacuum tubes, the Schröder is a directly heated triode. Other arms are a garden variety pentode.
We proceeded with the rewire before diagnosing the reported problem.
Follow-up note: the rewire solved the tracking issue. We observed internal twisting of the wire which impeded the arm's free movement.
Using a Pet Peeve to Our Advantage
One of my pet peeves with both the Schröders and the Kuzma 4Points is their excessively long captive cables. They're 1.5m long. I learned that that this is to suit Japanese market which prefers long cables.
We put this quirk to our advantage - putting the excess length to good use, by creating a "new" harness. The bonus? A shorter cable means lower capacitance. What's not to like?
Prepare the Harness
Shielding & Outer Braid Removed
The first part is fairly straight-forward:
- Cut the cable at the base of the tonearm
- Strip away the outer black braid and the shielding braid to expose the inner, fiberglass sleeve
- Push the strain-relief collar towards the RCA connectors
- Slip a piece of 1/4" head shrink over the cable
Harness Part-2: Bring Your "A" Game for this Step
This step is not for the faint of heart.
The inner fiberglass braid is very tough and there's a high risk of nicking the four signal cables. The photo shows the end result.
High magnification, anchoring the wire on your workbench and several single edge blades are key to success. The fiberglass is very tough and dulls a blade quickly.
Don't skimp on blades. The price of a new harness (or starting over and losing more cable length) isn't worth it.
Fiberglass Braid Removed
Feed the New Wire Through the Arm
Prepare to Feed the Wire
Normally , one could solder the new wire to the old wire at the base of the arm and use the old wire to draw the new wire through.
In our case, 3 of the 4 signal wires were inside the VTA pillar and there wasn't enough free wire to do this.
We fed some stranded jacketed wire through the arm for this purpose.
Making the turn where you see the loop is a task unto itself. We developed a trick to make this bend and route the wire down the arm tube.
Not shown, we soldered the new cable to the "feeder wire" at the base of the arm and pulled it through. We taped the arm to our work surface to stabilize it, and carefully fed the wire - pulling gently from the headshell.
It's important to leave a bit of slack at the right angle bend to not stress the fragile litz, and so the arm moves freely.
Re-attach the Strain-Relief Collar
Slide the strain-relief collar to the end of the heat shrink, and tighten the set screw.
Gently feed the wire through the arm tube (as before), to move the strain-relief collar into position.
Tighten the set screw to anchor it in place.
Keep the tension on the litz as low as possible!
Attach Strain-Relief Collar
Install the Cartridge Clips
Cartridge Clips Installed
This litz wire is extremely fragile, and didn't take kindly to the temperature of our solder pot. Too high of a temperature vaporizes the wire. Additionally, the wrong flux won't work.
After experimentation with a test piece (from the cut away section), we settled on Cardas flux and solder, and set our Hakko iron to a temperature of 720F (382C).
If you use different solder or flux, you'll need to experiment with this step.
Stripping the wire involved adding flux and using the soldering iron tip as a mini-solder pot - adding a healthy blob of solder.
Good as New
That wasn't so hard, was it?
In all seriousness, there are quite a few hidden pitfalls that are beyond the scope of this article.
Only you can judge if you're up to the task.
If we didn't have extensive experience working with fine gauges of litz, we would never take project like this on.
Even with this experience, you need to be on your game - especially the step where you strip the fiberglass braid.
Ready to Mount
Fault Analysis
The problem arose when our customer encountered a cartridge for which he could not set enough anti-skating force. In this rare instance, a stronger magnet can be sourced from Thrax.
Our customer was advised to rotate the arm wand about the VTA pillar multiple times, in order to effect "mechanical anti-skate". Don't try this at home folks, or you'll run into the same problem.
Consider how fine this wire is and you'll learn two things:
- The wire is fragile and may break as shown in the first photo.
- Before breaking, multiple twists will kink the wire and it will impede the free movement of the arm.
