Mitsubishi LT-30 restoration
- Thread starter kotofei
- Start date
Old Vinyl
New Member
Broken brass standoffs in tonearm
I have the tone arm apart and was able to get the broken off ends unscrewed from the underside of the tone arm. I have drilled out the standoffs and found some 2mm screws to repair at the hardware. Once screwed in the standoffs, I will cut them off to proper length. I had to order a 2mm cutting tap though that the hardware didn't have.
While its apart, I'm thinking about rewiring the tone arm. Cardas 33x4 shielded wires will be routed from the cartridge through the tone arm then directly to the RCA plugs on the pre amp. Bypassing the muting board seems like it should help sonically but without the mute, may be noisy when the stylus is being dropped or lifted from the record. Any comments?
Thanks for everyones help in this thread, the pictures and information were really helpful for this project.
Robert
I have the tone arm apart and was able to get the broken off ends unscrewed from the underside of the tone arm. I have drilled out the standoffs and found some 2mm screws to repair at the hardware. Once screwed in the standoffs, I will cut them off to proper length. I had to order a 2mm cutting tap though that the hardware didn't have.
While its apart, I'm thinking about rewiring the tone arm. Cardas 33x4 shielded wires will be routed from the cartridge through the tone arm then directly to the RCA plugs on the pre amp. Bypassing the muting board seems like it should help sonically but without the mute, may be noisy when the stylus is being dropped or lifted from the record. Any comments?
Thanks for everyones help in this thread, the pictures and information were really helpful for this project.
Robert
Pio1980
AK Member
Be very careful of course not to get metal bits into the gimbal bearings. Prefect fix BTW, exactly as it should have been done IMO.
Yes, it will be noisier without automute which is pretty non-intrusive due to being basically a terminal board for the cart plug wiring tho' automute is incompatible with strain gauge carts and trans-impedance type preamps. The original arm wiring looks excellent to me, I replaced mine for being damaged during OEM assembly. Don't use the shielded portion of the new wire thru the gimbal passages as it is too stiff to allow free frictionless movement, best rewired as shown if done. Now's as good a time as any if desired, the shielding is unnecessary in the arm pipe and carriage base if correctly routed.
Yes, it will be noisier without automute which is pretty non-intrusive due to being basically a terminal board for the cart plug wiring tho' automute is incompatible with strain gauge carts and trans-impedance type preamps. The original arm wiring looks excellent to me, I replaced mine for being damaged during OEM assembly. Don't use the shielded portion of the new wire thru the gimbal passages as it is too stiff to allow free frictionless movement, best rewired as shown if done. Now's as good a time as any if desired, the shielding is unnecessary in the arm pipe and carriage base if correctly routed.
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Pio1980
AK Member
"While its apart, I'm thinking about rewiring the tone arm. Cardas 33x4 shielded wires will be routed from the cartridge through the tone arm then directly to the RCA plugs on the pre amp. Bypassing the muting board seems like it should help sonically but without the mute, may be noisy when the stylus is being dropped or lifted from the record. Any comments?"
Sounds like you pretty much know what you are doing, something like the Cardas Incognito continuous path re-wiring for REGA arms. Could be interesting.
Sounds like you pretty much know what you are doing, something like the Cardas Incognito continuous path re-wiring for REGA arms. Could be interesting.
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I've bypassed my muting board and love the difference it made. I only bypassed it to tame some odd behaviour with my Phonoclone but it had the added benefit of opening up the sound as well, the background became a little more black. The sound of needle drops doesn't bug me, and I rarely hear it actually when playing a clean record. The tonearm lifter moves very gently, I basically just hear the crackle from dirt and damage in the run-in groove. No more than I would hear doing a manual drop. Oh, and there is zero noise while the tonearm is moving. So I say go for it!!
MRL_Audio
RIP 2022
It's actually a cam on the bottom that drives a switch to move the location of the lead-in. If you open the bottom of the table you will be able to clearly id it and how the screw affects the cam and switch. I had to make adjustment to mine with some tape and a home made spacer. Worked fine. I'll be looking for a better solution soon.
Ok, I see the adjustment cam underneath that makes contact with a metal lever. Should that metal lever be spring loaded because it isn't moving otherwise, unless i move it by hand.
Pio1980
AK Member
The stop/park/rest adjustment 'T' shaped lever with the microswitch on the rearward adjustment cam has a tension spring on the rearward leg of the 'T', the front adjustment cam has it's tensioning spring on the opposite end of the long movable slotted metal piece and not at the lever. These adjustments are interactive with each other and the tracking tangency adjustment on the arm pillar base. See that the spring is on the sliding piece and that the piece can freely move.
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Those pictures helped, i had used the center screw holes instead of the upper ones, which had the plate locked down.
Next problem: i have no audio while unit is playing, any tips?
Old Vinyl
New Member
Damaged LT-30 Finally Fixed and Re-wired
Finally repaired the broken standoffs that actuate the tracking sensor inside the tone arm. I purchased 5 ft. of Cardas 4X33 shielded wire and ran this directly from the RCA plugs to cartridge clips. Could have used another half foot of the Cardas wire, I used every bit and ended up with a 39" RCA cable to the pre-amp. Its O.K., just a little shorter than it was. The original tone arm wire was broken inside the the the back of the arm inside the gimbal body, apparently when the standoffs were broken the tone arm would swing much further than it should and sheared the wires. Anyway, had to take everything back apart and disassemble the tone arm itself to feed the new wires through. Adjusted the gimbal bearings while I was in there since they were loose.
I used a Sumikomo HS-12 (I believe) and removed the nylon insert inside and epoxied the pins back in the headshell. Used Eichmann bullet plugs and had to split the Cardas wire into two separate bundles going to the RCA plugs. This was a real pain. Set the tracking angle with a HiFi News Test Record alignment protractor which can also be used to verify the 50mm length from stylus tip to back of cartridge by moving the tone arm back and forth verifying the protractor is parallel to the rails of the carriage.
All done now and sounds fantastic! Little or no hum at high volume, much less than my Thorens TD-126 or Dual CS-5000. I expect it to sound better when the stylus breaks in and the Phonomena II pre-amp, being new, should sound better after running for some time. This may replace the Thorens as my reference turntable!
Finally repaired the broken standoffs that actuate the tracking sensor inside the tone arm. I purchased 5 ft. of Cardas 4X33 shielded wire and ran this directly from the RCA plugs to cartridge clips. Could have used another half foot of the Cardas wire, I used every bit and ended up with a 39" RCA cable to the pre-amp. Its O.K., just a little shorter than it was. The original tone arm wire was broken inside the the the back of the arm inside the gimbal body, apparently when the standoffs were broken the tone arm would swing much further than it should and sheared the wires. Anyway, had to take everything back apart and disassemble the tone arm itself to feed the new wires through. Adjusted the gimbal bearings while I was in there since they were loose.
I used a Sumikomo HS-12 (I believe) and removed the nylon insert inside and epoxied the pins back in the headshell. Used Eichmann bullet plugs and had to split the Cardas wire into two separate bundles going to the RCA plugs. This was a real pain. Set the tracking angle with a HiFi News Test Record alignment protractor which can also be used to verify the 50mm length from stylus tip to back of cartridge by moving the tone arm back and forth verifying the protractor is parallel to the rails of the carriage.
All done now and sounds fantastic! Little or no hum at high volume, much less than my Thorens TD-126 or Dual CS-5000. I expect it to sound better when the stylus breaks in and the Phonomena II pre-amp, being new, should sound better after running for some time. This may replace the Thorens as my reference turntable!
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Renfield72
New Member
So, how do i fix it? I presume replacement switches are unobtanium. Bypass it? Eek, hate to open it up again.Muting switch is malfunctioning if there is nothing else amiss, it's the one on the board with the white lever that works off the lift cam in the pillar base.
Also, the tonearm is not tracking/moving along with the record.
Pio1980
AK Member
The clue to whether the tracking lamps and detectors are working is whether moving the arm left-right caused the arrows to light appropriately, whether or not the arm moves. Next the shuttle buttons should move the arm left/right when pressed with the arm cued up and not down. Lastly, cued down the arm's deflection should cause the arm to move appropriately with no effect from the shuttle buttons when cued down. The shuttle buttons should cause the arm to cue up before moving in the appropriate direction.
Get back with observations to go further.
Get back with observations to go further.
MRL_Audio
RIP 2022
I have one LT-30 where the arm moves as Pio describes but... where the center light should be lit when perfectly aligned both the right and left arrows light at the same time. The arm works fine, when lifted to the left the arm move left and the left light is lit. Same is true when lifted to the right. When balanced both arrows light and not the center. Still need to figure this one out.