AVForums South Africa

Audio and Video Talk => General Discussion => Topic started by: vleisman on January 13, 2021, 07:35:24 PM

Title: Micro Seiki MA-100S tonearm info
Post by: vleisman on January 13, 2021, 07:35:24 PM
Anyone know anything about this beautiful arm. I got one with a TT that I bought, kindly delivered to me by an awesome forum member. There are a couple of issues with the arm:

1. The anti-skate weight - not sure what I have is standard. Also not attached to the arm, needs gut replaced - and I'm not sure how it is supposed to work, as in routing of the gut and how it's attached to the arm.
2. Downforce adjustment - similar story as above.

These arms seem extremely scarce, I can't find a user manual or service info for this one. Any assistance appreciated.
Title: Re: Micro Seiki MA-100S tonearm info
Post by: vleisman on January 13, 2021, 08:15:00 PM
Some pics to show off and for reference

(https://uploads.tapatalk-cdn.com/20210113/44c533b8a423c051507cbc844af7ef80.jpg)(https://uploads.tapatalk-cdn.com/20210113/f6559738dce39739604263af3eec31d4.jpg)(https://uploads.tapatalk-cdn.com/20210113/60a801348b4325f9d25a60b92080fd05.jpg)

Sent from my DUB-LX1 using Tapatalk

Title: Re: Micro Seiki MA-100S tonearm info
Post by: Zilch on January 13, 2021, 09:59:41 PM
Damn that look good!  What turntable?
Title: Re: Micro Seiki MA-100S tonearm info
Post by: vleisman on January 13, 2021, 10:26:57 PM
Some old English rumbler, nothing special  :angel:
Title: Re: Micro Seiki MA-100S tonearm info
Post by: Zilch on January 14, 2021, 09:46:42 AM
Hmm... looks like a 301 :thinking:
Title: Re: Micro Seiki MA-100S tonearm info
Post by: johan.pretorius on January 14, 2021, 10:09:40 AM
Hmm... looks like a 301 :thinking:

Right, nothing special then :-)
Title: Re: Micro Seiki MA-100S tonearm info
Post by: vleisman on January 14, 2021, 10:30:37 AM
Had a call from Fredeb last night and he gave me some good pointers.  :thumbs: I plan to document the process here in this thread, in case anyone else stumbles upon one of these. Also to remind me what I did one day, my memory isn't tremendous.
Title: Re: Micro Seiki MA-100S tonearm info
Post by: fdlsys on January 14, 2021, 12:36:21 PM
Hmm... looks like a 301 :thinking:
Nope. 401.
Title: Re: Micro Seiki MA-100S tonearm info
Post by: Zilch on January 14, 2021, 12:44:43 PM
Anyone noticed I somehow broke the 'like' system in reply #0 and #5 :BWAHAHAH:
Title: Re: Micro Seiki MA-100S tonearm info
Post by: vleisman on January 17, 2021, 02:37:28 PM
There were 3 issues with this arm
1. Broken arm stand /holder that has been glued back. Not much one can do without parts except clean it up and reglue
2. Anti skate gut is not attached.
3. Some weird weight spring adjustment mechanism also not attached. The jury is still out on what this thing actually does.

The arm rest thing was an easy fix


(https://uploads.tapatalk-cdn.com/20210117/95017740962aba29085bea1eae643785.jpg)

Sent from my DUB-LX1 using Tapatalk

Title: Re: Micro Seiki MA-100S tonearm info
Post by: vleisman on January 17, 2021, 02:41:46 PM
The anti skate is a bit more complex. Disassembly consists of removing the top assembly by removing 4 screws, 2 on each side. No need to loosen the red middle screw yet, but can also be done.

(https://uploads.tapatalk-cdn.com/20210117/c4447579af3d7ef0ffc7b725f73c7154.jpg)(https://uploads.tapatalk-cdn.com/20210117/0b0db1a5d7ed8017145e6fd8b7763ca6.jpg)

Sent from my DUB-LX1 using Tapatalk

Title: Re: Micro Seiki MA-100S tonearm info
Post by: vleisman on January 17, 2021, 02:44:12 PM
That exposes the central part that holds the scale wheel in place. Loosen the red screw and remove.

(https://uploads.tapatalk-cdn.com/20210117/bba3a18bc8a279a1f7e48f5ac31b7966.jpg)(https://uploads.tapatalk-cdn.com/20210117/eec5244f4e38958433098b522472ac1d.jpg)

Sent from my DUB-LX1 using Tapatalk

Title: Re: Micro Seiki MA-100S tonearm info
Post by: vleisman on January 17, 2021, 02:49:08 PM
The gut that holds the weight winds around the spiral plastic disc that sits under the scale wheel.
The gut is anchored to the hole somehow. This took a while to sort out. Ended up sticking a toothpick through the hole, attaching the gut to the toothpick and then smoothing everything down so the disc and wheel can turn freely.
(https://uploads.tapatalk-cdn.com/20210117/0c3dec669afc1421089616a86cd81178.jpg)(https://uploads.tapatalk-cdn.com/20210117/151b245d286dd2ae32b0e3c8f8d5e39b.jpg)(https://uploads.tapatalk-cdn.com/20210117/b776bf34bf8a6026f6e38f9e99262059.jpg)

Sent from my DUB-LX1 using Tapatalk

Title: Re: Micro Seiki MA-100S tonearm info
Post by: vleisman on January 17, 2021, 02:53:17 PM
Some more pics of the anti skate surgery

The pin on the plastic disc locks the scale wheel in place through the little hole(https://uploads.tapatalk-cdn.com/20210117/159fddd878742a99a8061ee37b6f115b.jpg)(https://uploads.tapatalk-cdn.com/20210117/1fe8ad2a8960570b200091c44be3ebf8.jpg)(https://uploads.tapatalk-cdn.com/20210117/0597042007321fbe9aa9a7f206b70b4b.jpg)(https://uploads.tapatalk-cdn.com/20210117/0fe8d9aefd55afb4257494d2fc0c405d.jpg)

Sent from my DUB-LX1 using Tapatalk

Title: Re: Micro Seiki MA-100S tonearm info
Post by: vleisman on January 17, 2021, 02:59:34 PM
Another tricky bit is getting the length of the gut right. The platter on this deck is high, so the arm sits high, but there is still not enough space to use the full range of movement. Still the basic functionality is working so that will do for now.

Also need to replace the grease to give more resistance to the disc movement, at the moment it either sticks or runs.



Sent from my DUB-LX1 using Tapatalk

Title: Re: Micro Seiki MA-100S tonearm info
Post by: Zilch on January 17, 2021, 03:21:55 PM
This is awesome!  But shouldn't it be in the DIY section?
Title: Re: Micro Seiki MA-100S tonearm info
Post by: vleisman on January 17, 2021, 03:58:53 PM
Next up is the mysterious adjustable weight / spring mechanism. For the life of me I am not sure what it does, but it's a beautifully designed and engineered thing. This is an adjustable arm that suits on top of the actual arm. The base covers the anti skate assembly but has no real influence there as far as I can see. There seems to be some relationship as the scale of adjustment is similar to the anti skate scale, from zero to 3.5ish.
The adjustment wheel on the front moves an aluminium slider inside the small arm, so basically moves weight closer to or further from the arm pivot point. Then there is a piece of gut that attaches to a weight on the one end and a spring on the other. This gut was loose on the weight end.

(https://uploads.tapatalk-cdn.com/20210117/03d135ff2249daec637ad93330c29ca9.jpg)(https://uploads.tapatalk-cdn.com/20210117/11d0d7d27f3b350ffb0ccea4dbe11bfa.jpg)(https://uploads.tapatalk-cdn.com/20210117/ff203ca6e6b6888f539a4c70eeaf8403.jpg)(https://uploads.tapatalk-cdn.com/20210117/3beb4754985bea3fbc9edaacd79bfbcd.jpg)

Sent from my DUB-LX1 using Tapatalk

Title: Re: Micro Seiki MA-100S tonearm info
Post by: vleisman on January 17, 2021, 04:02:34 PM
Once I figured out how it was pieced together the fix was relatively straightforward. Attach the new gut to the spring, route it over the little wheel through the hole and attach the weight.

Again the length is tricky and I made it a bit too short so the spring is permanently under a bit of tension. If I find out what it does I'll worry about that.

(https://uploads.tapatalk-cdn.com/20210117/50b3f29bd3f7856aadff82d1ad8c8c9e.jpg)

Sent from my DUB-LX1 using Tapatalk

Title: Re: Micro Seiki MA-100S tonearm info
Post by: vleisman on January 17, 2021, 04:05:00 PM
The headshell on this is an SME which is much too light for the arm. A highly technical fix of prestix is currently keeping things stable until I can source a proper headshell.

(https://uploads.tapatalk-cdn.com/20210117/5866d0b44fb940dae59ad95b5e8221ae.jpg)

Sent from my DUB-LX1 using Tapatalk

Title: Re: Micro Seiki MA-100S tonearm info
Post by: vleisman on January 17, 2021, 04:10:45 PM
A few remaining niggles. The arm rest doesn't restrict or hold the arm at all, need to MacGyver something here.
The arm lift action is a bit jerky.
(https://uploads.tapatalk-cdn.com/20210117/0cd253369ce6e2e8ea6d312682980343.jpg)

Sent from my DUB-LX1 using Tapatalk

Title: Re: Micro Seiki MA-100S tonearm info
Post by: vleisman on January 17, 2021, 04:11:53 PM
Big thanks to Fredeb for all his help and advice  :thumbs:
Title: Re: Micro Seiki MA-100S tonearm info
Post by: fredeb on January 17, 2021, 11:40:43 PM
Big thanks to Fredeb for all his help and advice  :thumbs:

Apologies for only looking in here now - been crazy busy .

Looks like you're doing well with getting everything functioning properly . Seems the only thing you need to sort is the arm-lift . Careful manual needle dropping for now .

I think that the spring with counter-weight being adjusted higher or lower would make small changes of resonant frequency of the needle in the groove , allowing tweaking of cartridges of differing compliance . If you have a couple of different cartridges , you can try them all on the same arm with the same head-shell . If the match between the arm and cartridge is bad , you can actually see the stylus vibrating unstably in the groove . Be sure to use an LP you don't mind messing up , from the junk pile as it were .

I have no idea what the effective mass of this arm is , but I'd guess high . Therefore a low compliance cart would be a good match . Another methods of matching would be changing the head-shell mass , like your prestick solution .  ;D Easier to adjust with low compliance cartridges I think . More difficult to lower effective mass of high effective mass arms for high compliance cartridges . May as well start with a low dynamic compliance cart to start with .

Let us know how the setup sounds .  :thumbs:
Title: Re: Micro Seiki MA-100S tonearm info
Post by: naboo on January 19, 2021, 07:57:30 AM
The gut
that holds the weight
winds around the spiral plastic disc
that sits under the scale wheel.
The rusty wire
that holds the cork
that keeps the anger in.

Sorry, Ingvar got me going on Pink Floyd lyrics last night and I now I literally see them everywhere.

Nice job @vleisman and thanks for documenting. Maybe someday I'll get something fancy with wires :groovy: