Technics 1520 motor help

[sk8ter]

Hello. I am really embarrassed... as i have forgot how to put back together the capstan motor ..there is nothing in the service manual or pictures on the net...

The reason i took it apart to oil the bearings....well I found out that these are ball bearings! and somewhat sealed....but i did put some oil in them ..but i forget exactly how it goes back together...pictures would be nice

I am about 3/4 done with recapping the unit....I am looking forward to hearing it after all this work!

before i decided to do this work it was running good and I have a master tape someone did ...man this deck is dynamite

Thanks for your help

Lawrence

[ironbut]

Hey Lawrence,

Welcome to the forum.

First off, you shouldn't oil sealed bearings. They are packed with grease  which helps keep the bearings quiet (learned this the hard way!).
You should probably take the motor to a bearing shop and have the bearings replaced now. The don't have to be any super duper expensive bearings but well made ones (in other words, No bearings from no-name shops overseas even if they are ceramic. Bad bearings can be made out of anything and it's more about the quality of manufacturing (Japanese or American made bearings should do great in this application).

Regarding the correct order that the motor is reassembled, I'll need to get some time to pull a spare I have apart and post later. I'm in the middle of something right now so it may be a week or so.
Maybe someone else here can get to it before me. It's been a while since I pulled the capstan motor apart.

In the future, a good idea when you take anything apart is to keep a digital camera or phone at hand. Snap pictures along the way and it can act as your digital memory (learned that one the hard way too!).

[sk8ter]

any help with this will be greatly appreciated....yes i pulled it apart because i thought it was a plain bearing and not ball bearings ....yes i looked into replacements....IMO there is nothing really wrong with them still tight and free. i repacked them......most bearings today even abec 7 are not this good!

I did manage to put the motor back together but i am wondering if it is correct and is there some special way to orient it? there is a non metal non conductive black washer too......the motor is non functional now and the transistors that power the thing get warm within a few moments it does try to start...I hope i did not break a wire...as i am very careful I cannot tell you how upset I am now that my deck is not working....seems I have ut oh moments when i do stuff for myself!

I really messed up...

[ironbut]

Sometimes when you "oil" older sealed bearings, the oil will loosen up hardened grease and make the bearing "crunchy" sounding (at least, that's what happened to me).

Maybe a stupid question, but did you hold down one of the tensioners while you tested the capstan motor?

[sk8ter]

Yes sir..I most certainly did .....several times...I took the motor back apart and looked very carefully..I have excellent close vision(I do cartridge retipping) ...I did not see any broken wires....so I am at a loss...if you would please have a look ...I cannot focus on much else until this is resolved I am crazy like that..


Lawrence

[sk8ter]

ok you convinced me ...I bought some nsk Japan bearings...I know these are real good quality!...


anyone have more ideas on my problems...

Lawrence

[Tim]

Does the flywheel/capstan assy now spin quite freely (no power, by hand) as it did prior to you taking the motor apart? If yes, then the defect has nothing to do with the bearings.  If no, does it spin at all or is it just hard to turn? If no spin at all, check the spacing between the flywheel and the toothed tacho pickup that runs on the peripheral of the motor.  Should be a small spacing (~1/32").  If zero, then that the problem (incorrect flywheel height).

[sk8ter]

Hello Tim I did not take tack (metal) tooth ring off so but I do not see a spacer per say but yes the motor i can make it free turning....my question is if you have taken these apart how the washers go? is there the metal washer that is on the center race of the bearing then the large spring washer then larger washer then cir clip and on top of the cir clip is the non metal black washer?

if you would please give me a run down on how this is suppose to be?


thank you

Lawrence

[ironbut]

Before you get into serious troubleshooting, be sure that all fuses are good and that the machine hasn't been switched to battery power somehow.
Also, did you test the machine after re capping?
And what problems made you decide to recap?

The first thing I do when I start pulling a machine apart it to wrap the wiring harness in a way that makes more sense. I think that most machines come stock with the wires set up for the assemblers.
In other words, isolate the wires to the ones that go to the capstan motor. This makes it easier to track down electrical issues (like the one it appears you're experiencing).
Fixing this problem is going to be much easier if the capstan motor is out of the machine. It could easily be that one of the wires leading to the circuit board that pokes out of the motor unit was a little iffy and when you handled it to pull and replace the unit, it broke.
When testing, it's easiest to rig up some sort of frame that you can mount the capstan motor on. I just have an old piece of plywood that I drilled a couple of holes in and use a long bolt/nut to hold the unit. I put a weight on the other end of the wood so the capstan will hang over the edge of my table. If you don't do this, when the capstan starts turning, it'll spin off the table and that could break even more connections.
Once the capstan is secure, plug the connector back where it should be. You might as well use a tiny bit of contact cleaner on those connections just in case.
Use a piece of tape to hold down one of the tensioners.
Than one by one, wiggle the wires at both ends and see if that gets the motor going.
If that doesn't help, try the same procedure with all 3 tape speeds.

[sk8ter]

Ok i will give it a go but I really need to find out what i wrote about above...I think somehow this has some relevance...I will do this and report back in a few..



Lawrence

[sk8ter]

ok done this nada....I will say that the power transistors to control turn the motor get rather warm within a few 5 seconds but nothing happens(motor does not turn)


I also wanted to say if the motor is unplugged from the circuit board those transistors do not get warm!...so its in the motor I think?...if you have a readily avialable motor can you please pop the Eclip and have a look inside

[sk8ter]

looking at the pinout on the schematic and the actual connector they do not match up! pin 1and2 have a small jumper across them there is no wire or pin on pin 3 and the rest have wires up till pin 15 but there is no pin 15 on the schematic!...whats going on here??

[Tim]

Hello Tim I did not take tack (metal) tooth ring off so but I do not see a spacer per say but yes the motor i can make it free turning...

I did not say you took the tooth ring off.  It is part of the flywheel and you did take that off.

I did not say there was a spacer. I asked for you to tell me the spacing between the teeth and the circuit board that picks up the signal that is generated by the teeth.  I told you it should be ~1/32" or 1mm.  It's it? The motor needs to be assembled to see the spacing.  If you have no idea what I am talking about, I suggest you take the deck into a RTR repair specialist (this may be beyond your expertize)

I don't know the proper order of washers within the motor. To operate properly, the spacing I talked about needs to be correct. That can be affected by the washers in the motor. Also, the flywheel needs to spin quite freely.  Also, is there a possibility you damaged one of the coils in the motor?  Check for that.

I agree with Ironbutt.  Check for broken wire between the motor and deck.

[sk8ter]

ok Tim will do ....no this is not beyond me ...I can do most things even very small cartridge repair...

Give me a few I will get back to you again...but like i said what would cause the power transistors to warm up?

[sk8ter]

ok I checked the spacing is about 32nd .031 and i rang out all of the wires from the plug to where they are soldered onto the board..all ring good!  ok now what?


Lawrence