Sony TC-K670 Capstan Motor

[Scorpion8]

So the TC-K670 that I calibrated and cleaned last week started acting up the moment I went to install the new ICs provided by Alex, the ANT4066A and the 5112. Geddy Lee was back to singing like the Vienna Boys Choir, so some poking around (and Alex's help) tells me the capstan motor is going snaky. I did a web search, and Sony Service Plus, PartStore and Encompass Parts are all "no longer available" for this part.

TG for the internet though. I did all my searching on the Sony p/n X-3356-635-1, which is a Panasonic MMI-6S2LKS DC12v motor. If you search on the motor itself, I found a thread on another site talking about replacements, including an MMI-5A2L or Mabuchi EG-500AD-2B motor. Both of those are in-stock at Encompass Parts, so the fix might be closer than I had originally fretted about.

Off to do more work and more research ....

ETA: the Mabuchi EG-530AD-2B is the same spec and hole spacing as the EG-500AD-2B except the body is a mite smaller.

ETAA: these motors are getting hard to find. Here's one source: http://audiolabga.com/noimage_1.html

[A.N.T.]

talking about replacements, including an MMI-5A2L or Mabuchi EG-500AD-2B motor.

I've got quite a number of these Mabuchi EG-500AD-2B motors. It is good to know that these may be useful for something!

Alex

[Scorpion8]

I've got quite a number of these Mabuchi EG-500AD-2B motors. It is good to know that these may be useful for something!

Alex

Where did you get yours from? Do they size up like a direct replacement for the OEM Panasonic model? Might I get one off you?

[jbeckva]

Hmm... these good for the TC-K690 too? I got me a screecher myself that needs a replacin'.

[Scorpion8]

Hmm... these good for the TC-K690 too? I got me a screecher myself that needs a replacin'.

Try lube? You sure it's the capstan motor? The -K670 has 3 motors inside.

[jbeckva]

Try lube? You sure it's the capstan motor? The -K670 has 3 motors inside.

Definitely - Doesn't keep the right play speed, either. I'll go for awhile "quietly" then screech so loud I can hear it from down stairs.

[A.N.T.]

Where did you get yours from? Do they size up like a direct replacement for the OEM Panasonic model? Might I get one off you?

I've looked inside of my Sony TC-K677ES (exactly the same mech as K670). The motor is MMI-6S2LKS. The Mabuchi motor is slightly larger in diameter (about 3 mm), otherwise it is the same size and on the same 1'' mounting holes distance. It will fit OK in the Sony mechanism. I may try to replace it just for fun to see how it performs. And you can certainly have one if you wish - for the price of postage. I have about 15 of those, I think.

Cheers

Alex

[jbeckva]

I've looked inside of my Sony TC-K677ES (exactly the same mech as K670). The motor is MMI-6S2LKS. The Mabuchi motor is slightly larger in diameter (about 3 mm), otherwise it is the same size and on the same 1'' mounting holes distance. It will fit OK in the Sony mechanism. I may try to replace it just for fun to see how it performs. And you can certainly have one if you wish - for the price of postage. I have about 15 of those, I think.

Cheers

Alex

How about the 690?

[A.N.T.]

How about the 690?

According to the service manual the mechanism on the K690 is exactly the same as on K670/K677ES

Alex

[Scorpion8]

I've looked inside of my Sony TC-K677ES (exactly the same mech as K670). The motor is MMI-6S2LKS.

Should be, the mechanism is the same in both decks. I've read some disparraging things about the Panasonic motor online, but I can't say I've ever had mass-faults with them.

[speakerman1]

Definitely - Doesn't keep the right play speed, either. I'll go for awhile "quietly" then screech so loud I can hear it from down stairs.

I have some Deoxit D5 if you need it. I had one squeel and I used the deoxit . It is still running fine. I have a spare.
Larry

[Scorpion8]

DeOxit works on some ills, but not a failing motor controller. But on some of this vintage gear it's always a good place to start in a restoration.

[Scorpion8]

I replaced the motor today with a Mabuchi EG-530AD-2B and wrestled with it all day. Not the install, that was easy. Sony transport back-halfs come off for access to the belts like a breeze. New motor was playing at dead slow (so I've gone from Alvin & The Chipmunks to Slooooooooooow....). Bad motor, me thinks.

So I happened to have one more at home (I had squirreled these away years ago and forgotten), and broke it out today. Hooked them both up to 12VDC and the difference was obvious. So am taking the new motor into work tomorrow to install, and taking the old motor to the range for a lil' target practice....

Stay tuned ....

[Scorpion8]

Conundrum.... the 2nd capstan motor appears to be running at half-speed also. *dunno* Now I'm vexed....

[A.N.T.]

Conundrum.... the 2nd capstan motor appears to be running at half-speed also. *dunno* Now I'm vexed....

Did you check 12V supply on the motor?

Cheers

Alex

[Scorpion8]

Did you check 12V supply on the motor?

Cheers Alex

Yup. It says 12V in the right direction. *dunno*

[Warped Bezel]

Yup. It says 12V in the right direction. *dunno*

Is there an adjustment hole on the back?

There's a capacitor or two around to also, no?

It's a Psychic Hotline guess but...

Oh yeah...is there music search?

[Scorpion8]

Is there an adjustment hole on the back?

There is, but it'll adjust the speed +/- 3%, not +/- 50%

There's a capacitor or two around to also, no?

It's a Psychic Hotline guess but...

Oh yeah...is there music search?

Yes to AMS (auto music search). No caps in the circuit between the 12V rail and the motor.

[Scorpion8]

So last night I'm pawing around on the schematic for the TC-K670 looking for some variable I can change to make these motor(s) work. They are (spec-wise) direct replacements for the Matsushita MMI-6S2LKS that came out of the deck. So *dunno* ... but (there's always a "but") while reading the schematic, the motor shown as the capstan motor on the schematics differs from the table of parts and the motor that got removed. Huh?!? The motor on the schematics is a Matsushita MMI-6H2LWK. Oddly, this is a dual-speed motor from the literature that I can find online and the high-speed is 4000rpm, not the 2400rpm of the "stated" motor. Of course, now I'm truly confused.

As luck would have it, the Sony deck I cannibalzed here (http://www.tapeheads.net/showthread.php?t=6515) had two MMI-6H2LWK motors in it that I pulled out and saved (whew!) so I'll try one of those. Since they are much faster rated speed, they may solve the running-slow mystery. I'll just only hook up two of the leads instead of all four connections for the fast primary speed.

That doesn't solve the mystery of why direct replacement motors don't run at the right speed, and why the schematics, parts list, and actual-installed-part don't all match.

But who cares as long as it works. *hope*

A.N.T.... your motors arrived today.

[A.N.T.]

So last night I'm pawing around on the schematic for the TC-K670 looking for some variable I can change to make these motor(s) work. They are (spec-wise) direct replacements for the Matsushita MMI-6S2LKS that came out of the deck. So *dunno* ... but (there's always a "but") while reading the schematic, the motor shown as the capstan motor on the schematics differs from the table of parts and the motor that got removed. Huh?!? The motor on the schematics is a Matsushita MMI-6H2LWK. Oddly, this is a dual-speed motor from the literature that I can find online and the high-speed is 4000rpm, not the 2400rpm of the "stated" motor. Of course, now I'm truly confused.

As luck would have it, the Sony deck I cannibalzed here (http://www.tapeheads.net/showthread.php?t=6515) had two MMI-6H2LWK motors in it that I pulled out and saved (whew!) so I'll try one of those. Since they are much faster rated speed, they may solve the running-slow mystery. I'll just only hook up two of the leads instead of all four connections for the fast primary speed.

That doesn't solve the mystery of why direct replacement motors don't run at the right speed, and why the schematics, parts list, and actual-installed-part don't all match.

But who cares as long as it works. *hope*

A.N.T.... your motors arrived today.

Hi Jim,

Good to know that the mail works fine!

On the speed issue. I've opened my K677ES just now. The motor is MMI-6S2LKS. I've measured the diameters of the motor pulley, the capstan flywheel and the capstan itself. These are 7.3mm, 42.7mm, 2.25mm . A simple calculation gives almost exactly 2400 rpm for the motor speed. Unless the pulley on the motor is of a different diameter, you need 2400 rpm motor!

Cheers

Alex

[Scorpion8]

A simple calculation gives almost exactly 2400 rpm for the motor speed. Unless the pulley on the motor is of a different diameter, you need 2400 rpm motor!

Thanks Alex. The TC-K670 transport is identical in every way to the TC-K677ES transport according to the SM. So.... the old motor was the same between mine and yours, and the new motors were rated for 2400rpm. So why don't they spin the deck at the right speed?

[Scorpion8]

Hey Alex -- What does shorting the CNE707 test point do in the tape speed adjustment procedure? Is there some "master reset" of the main logic IC that I need to "reboot" this deck?

[A.N.T.]

Hey Alex -- What does shorting the CNE707 test point do in the tape speed adjustment procedure? Is there some "master reset" of the main logic IC that I need to "reboot" this deck?

Hi Jim,

The CNE707 is for testing the processor, I think. The speed is not controlled by the processor - 12V supply is connected to the motor through only a fuseable resistor and the motor should rotate (with the right speed) all the time. Did you try any of my motors?

Cheers

Alex

[Scorpion8]

Did you try any of my motors?

Not yet. The deck is on my workbench at work, so it'll be Monday unless I can sneak down there.

So why does the procedure call for shorting this "test pin" set at CNE707?

[A.N.T.]

Not yet. The deck is on my workbench at work, so it'll be Monday unless I can sneak down there.

So why does the procedure call for shorting this "test pin" set at CNE707?

I don't know. It shouldn't make any difference to the speed or operation of the motor.

Alex.

[Scorpion8]

What about this R736 "fusible" resistor? That's the only component in-line with the motor and yet I was reading a good 12.44 Vdc across the motor. Could it be current limiting?

[A.N.T.]

What about this R736 "fusible" resistor? That's the only component in-line with the motor and yet I was reading a good 12.44 Vdc across the motor. Could it be current limiting?

Again, it is either OK or it is open circuit, it can not do a current limiting. If you have 12V across the motor it should be all you need.

Cheers

Alex

[Scorpion8]

If you have 12V across the motor it should be all you need.

I'd be flamboozled if I had two motors on hand and both of them where off-spec. I noticed that yours are the EG-500AD-2B version that was replaced by the EG-530AD-2B models I have. Wonder if there's any true difference? *scratchchin*

[jbeckva]

Yooze guys are going to make me pull my TC-690 out and put that motor in it, aren't you?? *eyepop* You're peaking my curiousity now... *reelspin**reelspin*

(hey A.N.T. - got the motor and the other stuff.. thanks very very muchos!)

[A.N.T.]

I'd be flamboozled if I had two motors on hand and both of them where off-spec. I noticed that yours are the EG-500AD-2B version that was replaced by the EG-530AD-2B models I have. Wonder if there's any true difference? *scratchchin*

Jim, the 500 is quite different as it has a rubber suspension inside and possibly a different speed control circuit.

Cheers

Alex

[Scorpion8]

...the 500 is quite different as it has a rubber suspension inside and possibly a different speed control circuit.

Any thoughts then on which one to roll-the-dice with first?

[Warped Bezel]

There is, but it'll adjust the speed +/- 3%, not +/- 50%



Yes to AMS (auto music search). No caps in the circuit between the 12V rail and the motor.


I had an MCS deck with a search circuit and the IC etc were tweaked and so was the drive to some degree. I trust yours isn't as bad a setup.

[jbeckva]

Hey Jim!

Ok, so yeah I finally got off my butt and have my 690 in front of me. One thing I do notice off the bat is the color coding of the wires "isn't what one would expect"...

In other words (at least with mine)... the red striped wire is actually the negative pole!

Just checkin... what polarity do you have the red striped wire soldered to?

(hey.. can be an easy one?)

[A.N.T.]

In other words (at least with mine)... the red striped wire is actually the negative pole!

Same here on my K677ES.

Alex

[jbeckva]

Replaced the motor with Alex's - dialed in at 3K and good.

[Scorpion8]

Replaced the motor with Alex's - dialed in at 3K and good.

What model of motor did you use?

[jbeckva]

What model of motor did you use?

The EG-500AD-2B. Old one was a MMI-6S2LKS

Looked at the main pinch roller too.. way waaay too shiny so I scuffed it up a bit.

Got the PB levels and AZ "in", but now I'm at a conundrum... The SM shows the record pots way differently than what's really inside! I have 2 rec levels (ok, *check*.. no problem), 2 bias pots (yep, ok, *check*), but I also have two "EQ IV" in addition to the single "EQ IV" up near the record amp...

serious head scratching going on over here... *hypnot*

[Scorpion8]

The EG-500AD-2B. Old one was a MMI-6S2LKS

That's what I wanted to know. My "original" motor was the same model, and Alex sent me one of that replacement model also. I'll use one of those models in my install tomorrow.

[Scorpion8]

The EG-500AD-2B. Old one was a MMI-6S2LKS


Installed one of this model-version of the replacement motors. Fired right up at ~3kHz. It's running on a 30-minute warm in before I set the final speed but it started up right close to the proper speed to begin with.

Call me dumbfounded. *dunno*

I guess the salient lesson-learned here is not all direct-replacement motors are made equal. Time to add "motors" to that list of if-you-see-'em, cannibalize-'em!

[Scorpion8]

Ran all day, played all day.... seems to be dead-on. I'll start it up tomorrow AM and recheck the speed.

Alex -- I did notice that the SM calls for jumpering that test point before you power up the machine. When I did so, the whole display lit up like a X-Mas tree and displayed every dot-n'-digit. So it's doing some reset of the main logic IC of some sort. Silly me pulled the old motor first before checking to see if that would fix the slow speed issue. So that'll be a test for another day....

[A.N.T.]

I had today even more interesting experience with a motor replacement therapy. I have an old Technics RS-M253X which needed a motor. So I've installed EG-530AD-2B. And on a switch-on two fuses popped. Apparently, on that particular motor the case is connected to (-) supply. And on that deck the capstan motor supplied by a negative rail -14V. I've just shorted that power rail to ground. At least no other damage and after fuses replacement (and a motor replacement with EG-500 model) the deck is running fine. I just thinking if that ground connection could make somehow a difference in speed in your case?

Cheers

Alex

P.S. - and the speed is certainly not controlled by the processor!