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Old 7th Mar 2019, 6:05 pm   #1
Ebo1974
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Default Toshiba 1976 music system SM-3150 turntable problems

Hi I'm new to the site and looking for some help. I have a Toshiba music system sm3150 and I'm having problems with the record player. When I play a vinyl now the platter doesn't stop spinning. I try to use the play/cut switch but it still continues to spin. I found the only way to stop it is by lifting off the platter and mat and touching something on the main gear, possibly the hand clutch or auto clutch. I'm guessing it's this and only from service manual I got this info but I'm still not sure. There was a problem with the play / cut switch before this where the stylus wouldn't touch the record unless switched again to lower it. The cue lever is working fine.

If anyone can help I would be really grateful as I don't have experience on these things.
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Old 7th Mar 2019, 11:19 pm   #2
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

This may be what is commonly known as the Cam Gear/Trip Pawl assembly, and the cause may be dried grease preventing the correct operation of the mechanism. Whilst not being familiar with the Toshiba SM-3150, this problem is common to many record players. It is also possible that there is a plastic gear on the turntable spindle which has cracked and moved on it's shaft. I recently had that problem in a Sony Turntable.
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Old 8th Mar 2019, 2:27 pm   #3
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

Hi, thanks for your reply.

I think it's THE part in the photo. It seems that when I move it the platter stops spinning once I put the platter and mat back on
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Old 8th Mar 2019, 9:56 pm   #4
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

That is what I meant, Eko. The large wheel is called the Cam Gear, whilst the two levers are known as the Trip Pawl. The two parts of the Trip Pawl must be free to move,. so, if necessary, remove and clean them. I don't see how the cam gear is attached to it's shaft, but they were usually held by a circlip, though in many Japanese decks they are simply a push-fit, so the gear should also be removed, cleaned, and a small amount of grease applied to the groove on the underside. When re-assembling ensure that the Cam Gear is fitted correctly. As the gear is rotated, the trip pawl should move toward the centre spindle, at which point it should trip the auto stop mechanism. All of this depends on the white plastic gear on the centre spindle being in the correct place, not split, and not having moved out of place. I recently had this happen on a Sony Turntable, and, in the end, simply removed the white gear, and use the TT purely in Manual mode. On all iof the sometimes much maligned BSR & Garrard record decks made in the 60s, the centre and cam gears were all made of metal, so didn't crack or jam, though they still need cleaning & re-lubricating!
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Old 9th Mar 2019, 11:10 am   #5
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

There should also be a protrusion on the turntable centre boss, that knocks the trip pawl away as it comes around once every turn. The two metal surfaces slide over one another, since the force required to overcome the friction between them is less than the force that would be required to knock the stylus out of the groove. When the stylus reaches the widely-spaced run-out grooves at the end of the record, the tonearm moves inwards rapidly. This time the two metal pieces move together, since the force required to overcome the friction between them is greater than the force required to push against thin air. The trip pawl engages with the turntable platter gear and allows the cam gear to be driven, completing the change cycle.
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Old 9th Mar 2019, 12:14 pm   #6
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

Thanks for that further explanation, Julie. It may help the OP understand how the autostop system works. I didn't think to explain it in detail, having serviced quite a few autochangers and auto-stop turntables over the years.
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Old 9th Mar 2019, 12:17 pm   #7
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

There's a sticky thread here describing how velocity stops work:-

https://www.vintage-radio.net/forum/...ead.php?t=8936
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Old 9th Mar 2019, 1:15 pm   #8
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

So far as I can make out there are two trip mechs. if both are not working it could be that both are stiff in their bearings or that the trip spigot is not in line with trip plate upstands that are supposed to engage with the spigot when auto or cut are actuated

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Old 9th Mar 2019, 2:34 pm   #9
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

It appeared to me that there are two trip pawls on that gear, although I've never seen a turntable with two. Could it be that the white gear around the centre spindle has, as i suggested, moved and/or split, causing the problem you suggest, lawrence?
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Old 9th Mar 2019, 2:48 pm   #10
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

I think we need some more feedback on this as to what's free and what isn't.

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Old 9th Mar 2019, 2:55 pm   #11
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

So far as I can make out, the "gold" pawl (at front, one thickness of metal) initiates the "load" cycle when struck by the plastic peg to its right which probably goes to the user control lever; and the "silver" one (at back, 2 thicknesses) is the one that initiates the "reject" cycle, either at the end of the record or when the user operates the control lever.

Doing it this way allows you to have a Fully Automatic Single Play action controlled by a single lever; it knows whether you mean "start playing the record" or "stop playing the record and return the tonearm to its rest" because the cam gear has two gaps in its teeth.
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Old 10th Mar 2019, 9:18 am   #12
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

Thanks for all the responses to my request for help.

As far as I'm aware the trip pawls are both clean and free to move . There is nothing restricting their movement .

I'm really not technically minded when it comes to things like this. Though I have inspected the white centre cog and main cog, there are no cracks visible from the top. I have yet to take the player off to look underneath.

I got this system about 3 months ago and was told it had a full service, new bands for turntable and cassette plus new stylus. For me.. I personally think it's the play/cut switch as after playing a record and the stylus returns when playing another record and lifting the record across (manually) the tonearm/stylus doesn't lower enough to touch the record edge. However if you switch the play/cut switch it lowers and makes a click sound and continues to play the vinyl with no problems. I'm thinking did it have the full service or not?

I did try playing a 7" reord yesterday to see if it was still had the same problem and when the record finished the tonearm lifted,returned and the platter stopped. So I tried it again and it stopped again after playing. Now it could be something stopped was stopping too or it could just be OK for 5 minutes and it will play up again.

I really do appreciate everyone's help and I'm trying to learn as I go along
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Old 10th Mar 2019, 11:18 am   #13
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

The term "Play/Cut" switch does suggest it's a single lever which either starts the record playing or cuts it off prematurely.

Does the play/cut switch move that black plastic lever to the right of the cam gear; causing it to push the trip pawl, complete the gap in the gear teeth and start the cam gear moving?
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Old 10th Mar 2019, 11:25 pm   #14
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

This sounds like hardened grease, probably on some linkage on the play& cut control. Often, these things work when warm but if left for a while or used when colder, they stiffen. In any case, it probably didn't have the 'full service' - many people use that on auction sites yet lack the knowledge to do a thorough job. All they probably did here was give it a wipe with a cloth and let it play for a while!
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Old 14th Mar 2019, 9:43 am   #15
Ebo1974
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

Quote:
Originally Posted by julie_m View Post
Does the play/cut switch move that black plastic lever to the right of the cam gear; causing it to push the trip pawl, complete the gap in the gear teeth and start the cam gear moving?
Yes it does. I was pushing it trying to make the platter stop when it continuously spinned. I've not tried it for a couple of days as not been home.

Since Ive had the player I have used it most days and the play/cut switch has always had its problem.

I think it's me having a look underneath to check for grease etc. I'm nervous about doing it but I think I will give it a go.

Would anyone recommend using WD40 ? tiny amount ? Would this help? After removing grease if found ?
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Old 14th Mar 2019, 1:59 pm   #16
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

The white gear on the centre spindle? should that be attached to the underside of the platter?
Gaz.
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Old 14th Mar 2019, 1:59 pm   #17
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

I would avoid using WD40, if does n ot do what you think it does.
Clean off the old. dried up grease (it will be brownish in colour) with Isopropyl Alcohol or Meths and re-lube with Sewing Machine Oil and, where needed, a good auto quality Grease, or, if pushed, Petroleum Jelly.
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Old 14th Mar 2019, 2:24 pm   #18
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

If the Toshiba Mechanism is similar to Sony & Pioneer record decks, Gaz, the white gear is, or should be, firmly attached to the centre spindle, not the turntable underside. On Sony turntables such as the PS-D707, the centre spindle is made up of two metal shafts, the outer of which rotates around the inner, the turntable is a tight push-fit onto the spindle and thus rotates with it. Whether the same applies to the Toshiba deck I don't know. Perhaps another member does?

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Old 14th Mar 2019, 9:20 pm   #19
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

I still haven't looked underneath as there is another change . I've been playing it today and I've had no problems after it had a continuous spin. Doing the usual play/cut button. It stopped straight away ..however the cueing lever no longer works. Doesn't lift up the tone arm. Any vinyl I have played after it had stopped.

I won't use WD40 and I have sewing machine oil or petroleum if needed but I think with it going from one thing to another .. I think it could possibly gone beyond something I can fix and needs someone who knows what they are doing.

Appreciate the help and advice I
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Old 14th Mar 2019, 11:00 pm   #20
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Default Re: Toshiba 1976 music system SM-3150 turntable problems

I doubt that the cueing lever fault has anything to do with the cam gear/trip pawl assembly, but that could also be a lubrication problem. Don't try to force it, but can the cueing lever be raised at all?
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