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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 19th Jul 2023, 5:14 pm   #41
Karl T 01
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Default Re: Grundig TK 141

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Originally Posted by DMcMahon View Post
Thinking about it more, I think the referenced motor pulley safety fuse must be the silver conical shaped piece. On the wide end it has a small lip that looks to be possibly soldered. This end makes firm contact with the underside of the motor pulley by the action of the spring (which sits inside the conical piece) being compressed.

This firm contact enables the pulley to rotate when the motor rotates, if the solder melts due to overheated motor, then I guess this is enough to disable the pulley from rotating even though the spring is still compressed.

David
That's great to know, I had no idea where to look for the safety fuse. I'll have a look at that and maybe try to re-solder if needed. It's hard to believe that this all started after I made a mistake with a couple of drops of oil...
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Old 19th Jul 2023, 5:22 pm   #42
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Default Re: Grundig TK 141

Maybe a co-incidence or if oil made its way onto the spring/fuse/pulley contact areas this could allow the pulley drive to slip wrt to the motor shaft.

David
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Old 19th Jul 2023, 5:52 pm   #43
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Default Re: Grundig TK 141

The fuse ring is in a groove on the underside of the belt pulley. It's marked as part no 12 on the diagram attached earlier.

There could be two problems with the motor. One is that the belt is too tight and is pulling the bearings out of line, the other is that the bearings still need a slightly firmer tap to align them. Knock the shaft in the direction that you think will help and that should do it.

Paula
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Old 19th Jul 2023, 6:06 pm   #44
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Default Re: Grundig TK 141

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Originally Posted by frsimen View Post
The fuse ring is in a groove on the underside of the belt pulley. It's marked as part no 12 on the diagram attached earlier.

There could be two problems with the motor. One is that the belt is too tight and is pulling the bearings out of line, the other is that the bearings still need a slightly firmer tap to align them. Knock the shaft in the direction that you think will help and that should do it.

Paula
Yeah I'll give that a go, I tried tapping downward, I'll try tapping it to the left.
Something I noticed when pushing it back with the screwdriver is that the motor moves in the direction I'm pushing, then just seems to settle back into the position that's causing the problem. So yeah tapping it might be a better idea. Thanks
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Old 19th Jul 2023, 6:06 pm   #45
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Default Re: Grundig TK 141

My TK146 was replaced soon after purchase in 1971 because of a noisy motor. There was a batch of bad motors used in these recorders said the manager of “Civic” where I bought it. I wonder if this may be the problem here.

Peter
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Old 19th Jul 2023, 6:08 pm   #46
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Default Re: Grundig TK 141

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Originally Posted by DMcMahon View Post
Maybe a co-incidence or if oil made its way onto the spring/fuse/pulley contact areas this could allow the pulley drive to slip wrt to the motor shaft.

David
Yeah, it was a little bit squeaky before I put the oil on, spun perfectly for about 30 seconds then began to grind.
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Old 19th Jul 2023, 6:17 pm   #47
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Default Re: Grundig TK 141

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My TK146 was replaced soon after purchase in 1971 because of a noisy motor. There was a batch of bad motors used in these recorders said the manager of “Civic” where I bought it. I wonder if this may be the problem here.

Peter
It looks like somehow the whole shaft and motor system has moved slightly, (a couple of mm) out of place. I know only what I've read on the forum and replies on this thread about Reel to Reel players but I've done quite a bit on vintage road bikes. In that field noises tend to be from parts rubbing or not mounted properly, a visual examination tends to reveal the problem. With this one I can see what appears to be causing the problem but have no idea how it happened or what exactly will fix it. The answers here have been great, a new possible angle opens up every time.
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Old 19th Jul 2023, 7:09 pm   #48
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Default Re: Grundig TK 141

It might be worth trying turning one or other of the bearing units through 180 degrees to see if that helps with the alignment if nothing else works.

Paula
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Old 19th Jul 2023, 7:27 pm   #49
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Default Re: Grundig TK 141

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Thanks the information is very much valued. I'm fairly bamboozled by the whole drive shaft thing at the moment. I'm fairly certain it has something to do with it pulling towards the right (towards the idler), and slightly to the front. In one of the videos I posted I was able to push the shaft slightly with a screwdriver and it ran perfectly. Took the motor off, checked the shaft for damage and checked if it looked straight and it seemed fine. After reassembling it again seems to be pulling to the right. The belt doesn't seem to be overly tight. I'm thinking maybe if I can get a piece of metal in to the side of the rubber cap below the drive pulley assembly it might stop the pull to the right.
Possibly due to the shaft alignment but I am not convinced myself but you with the actual hands/eyes on can make a better judgement call.

On my TK 146 with the top parts removed from the motor shaft I can clearly see that my motor shaft is biased towards the idler, i.e. the shaft is not vertical. By pulling down on the side of the motor assembly on the underside forcing the motor assembly to tilt over in the opposite direction to the tilted shaft I can get the motor shaft to go vertical but as soon as I release the motor assembly the shaft once again tilts over towards the idler. I think the bearing rubber resilient mount is just compressing when forcing the motor assembly over and so the shaft returns to the tilted position as the rubber mount uncompresses.

It may be possible by playing around with the U clamping piece and bearing positions to get a more vertical motor shaft, but I will not try this as mine currently has no operational problem.

First thing to double check is can you manually rotate the pulley without it slipping on the motor shaft, there should be no sign of slippage in either direction.

David
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Old 19th Jul 2023, 7:54 pm   #50
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Default Re: Grundig TK 141

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Originally Posted by frsimen View Post
The fuse ring is in a groove on the underside of the belt pulley. It's marked as part no 12 on the diagram attached earlier.

Paula
Yes had seen it as item 12 on the drawing but could not really make out the part physically.

Now looking again at the underside of the pulley I think I can see solder around the inside. So does this mean that the replacement part referenced in the servcie drawing would be a pulley (complete with solder fuse fitted) ? The service drawing seems to refer to just replacing the solder fuse ?

David
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Old 19th Jul 2023, 8:58 pm   #51
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Default Re: Grundig TK 141

I tried tapping from the side and had a look at re-soldering the fuse but I decided against doing that for now. The shaft rotates freely by hand. I'm certain I need at least one circlip as the original one looks slightly worn on one side and can be put on the shaft by hand. I've uploaded a couple of more videos. Shaft rotates freely and without any grinding until the belt goes on. I can see the motor underneath move towards the capstan as soon as I switch the machine on. It does this every time. The main reason I took the motor off was to see if I could find a way to stop it moving, (tightened up the nuts on the mounting). This has made no difference. I'll keep working on finding a way, possibly some sort of metal tie etc).
Thanks all, and in Particular David and Paula for giving me the benefit of your experience. I'll post if/when the solution is found...
https://youtube.com/shorts/0iF8fLpxez4?feature=share3
https://youtube.com/shorts/0iF8fLpxez4?feature=share3
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Old 19th Jul 2023, 10:21 pm   #52
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Default Re: Grundig TK 141

The noise on your video is something rubbing, but the question is what and where?

I have had trouble with the flywheel scraping on the chassis and that makes a noise not unlike the noise on the video. In my case, the upper plate had been tampered with and that had left the flywheel slightly out of alignment. If the paint on the screws on the upper deck is intact, that isn't likely to be the problem. A small drop of oil (small is the key word here!) on the felt pad at the top of the capstan shaft may help, as would some lubricant on the bottom bearing of the flywheel. If the flywheel bearings are dry there will be a greater load on that motor and that will tend to make the motor move more than it should.

The motor itself sits in rubber resilient bushes which should reduce the amount of vibration but will allow the motor to move a little. Constant tension from the belt could have distorted these over the years, allowing the motor to sit off square when it is running. Could you try turning the rubber mounts around so that the side which wasn't being compressed is facing the front of the recorder?

Paula
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Old 20th Jul 2023, 9:27 am   #53
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Default Re: Grundig TK 141

Yes the rubbing noise is bad. Is the same noise present when the pulley/flywheel are manually rotated ?

Has the fault symptom of the motor speed varying completely gone away ?

Am I correct to say that this rubbing noise is fairly recent and was not present with the original motor speed varying and subsequent initial good running ?

David
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Old 20th Jul 2023, 11:42 am   #54
Karl T 01
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Default Re: Grundig TK 141

Quote:
Originally Posted by frsimen View Post
The noise on your video is something rubbing, but the question is what and where?

I have had trouble with the flywheel scraping on the chassis and that makes a noise not unlike the noise on the video. In my case, the upper plate had been tampered with and that had left the flywheel slightly out of alignment. If the paint on the screws on the upper deck is intact, that isn't likely to be the problem. A small drop of oil (small is the key word here!) on the felt pad at the top of the capstan shaft may help, as would some lubricant on the bottom bearing of the flywheel. If the flywheel bearings are dry there will be a greater load on that motor and that will tend to make the motor move more than it should.

The motor itself sits in rubber resilient bushes which should reduce the amount of vibration but will allow the motor to move a little. Constant tension from the belt could have distorted these over the years, allowing the motor to sit off square when it is running. Could you try turning the rubber mounts around so that the side which wasn't being compressed is facing the front of the recorder?

Paula
I've applied a small bit of grease to the bottom bearing of both the flywheel and the motor shaft. Also a drop of oil on the felt pad. Changing the rubber mounts around sounds like a really good idea, I'll try that later this evening. Thanks Paula
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Old 20th Jul 2023, 4:35 pm   #55
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Default Re: Grundig TK 141

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Quote:
Originally Posted by frsimen View Post
The fuse ring is in a groove on the underside of the belt pulley. It's marked as part no 12 on the diagram attached earlier.

Paula
Yes had seen it as item 12 on the drawing but could not really make out the part physically.

Now looking again at the underside of the pulley I think I can see solder around the inside. So does this mean that the replacement part referenced in the servcie drawing would be a pulley (complete with solder fuse fitted) ? The service drawing seems to refer to just replacing the solder fuse ?

David
Forgot to add this photo attachment.

David
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Old 20th Jul 2023, 4:59 pm   #56
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Default Re: Grundig TK 141

The service information implies that the solder fuse was available as a spare, so presumably it was supplied as an item rather than with the pulley wheel as an assembly.

Paula
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Old 21st Jul 2023, 7:05 am   #57
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Default Re: Grundig TK 141

Yes and it references fitting in the replacement solder ring/fuse after removing old failed part, so presumably one should be able to remove the part if the solder has not melted.

Out of interest to see what the part actually looks like I tried to remove my one by pulling on the side walls that the motor shaft goes through but no sign of it wanting to budge.

David
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Old 21st Jul 2023, 3:07 pm   #58
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Default Re: Grundig TK 141

I removed the motor again last night. Swapped the rubber mounts around and reassembled. The noise was present, switching from play to fwd or rwd and back to play the rubbing noise stopped at times and then returned. After the deflation of the removal and reassembly I thought of the possibility of buying a NOS motor and shaft that's for sale on ebay.
I then remembered that when I replaced the belts I only replaced two of the three, (main belt and tape counter belt). Is it possible that leaving an old belt on may have caused the problem? I'd imagine the newer belt is stronger than the old one which goes to the right wheel. Do you think it's possible that this could be the root cause of the problem?
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Old 21st Jul 2023, 8:03 pm   #59
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Default Re: Grundig TK 141

Very dificult to know with any certainty, I would not discount any possibility at this stage but my gut feeling is that it is unlikely to be the culprit.

David
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Old 23rd Jul 2023, 3:22 pm   #60
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Default Re: Grundig TK 141

I think it was this Thread (although cannot now see which Post) that had a reference to label saying "do not re-oil the motor bearings".

I don't think I have seen similar label before on the Grundigs (or at least not noticed) but today saw such a label on the TK 19L PCB screening cover.

David
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