Whine from cassette deck when playing pre-recorded cassettes

[62vauxhall]

Just wondering if anyone else has experienced this. After I got this Realistic SCT3000 working, I've picked up a few pre-recorded cassettes. A couple of them (so far) cause what to me sounds like a steady tone at the very start of the tape. I'm guessing 2 to 3 KHz. It's not what I'd call a squeal (I don't think) and it's not the tape's tone sweep. Whatever it is, it lasts for a track or two then goes away and is coming from the deck and not from the speakers. I got to wondering if it is caused by tape degradation similar to reel tape. I did notice a deposit of some kind on the leading and trailing edges of the formerly pristinely clean R&P heads.

Another thought was that despite lubricating everything, the sound was originating from the deck itself because of the all the disassembly/re-assembly I did. But since the deck runs quiet without a tape in place, I think the transport is probably OK.

 

[orange]

First of all, I think you double posted this. See about getting one removed to alleviate a split conversation. Save this one of course...I'm about to try and SPLAIN.

It sounds like you have damaged tape. Check others that you either had in the same time frame or bought from certain sources (used or NOS) and compare them.

Their storage could have been at fault, or maybe this particular tape just decided to puke.

Which title and what record company made it, also it's relative age and storage if you know?

 

[Skywavebe]

The deck might be having a squeal due to the resistance the tape is giving to a belt pulley or slip clutch. It can happen at the beginning of tape and may not be the tapes fault. If you put the deck in play mode and then hold the take-up reel table still it might still do it. The deck if it has a felt disc slip clutch might be too much friction due to the old felt. This is why I put new felt into reel tables on the decks I work on.

 

[Lazarus Short]

​In my experience, some tapes squeal, and there is nothing you can do. I remember Ampex tapes being among the worst. Have you tried a premium tape in your machine?

 

[Northwinds]

In my experience, FF/RW the tape before playing usually acclimates the deck to it's own tension. On rare occasions, I have had to take cassettes apart and replace the graphite sheets the spools ride against

 

[62vauxhall]

The deck might be having a squeal due to the resistance the tape is giving to a belt pulley or slip clutch. It can happen at the beginning of tape and may not be the tapes fault. If you put the deck in play mode and then hold the take-up reel table still it might still do it. The deck if it has a felt disc slip clutch might be too much friction due to the old felt. This is why I put new felt into reel tables on the decks I work on.

I think you are onto something here. With a tape inserted and deck in Play, the noise is most intense at the very beginning then decreases as the takeup tape pack gets larger. If I grip the takeup spindle while in play I can feel the vibration.

The clutch was cause of much consternation in my attempt to get this thing working. The problem then, at least as far as I could tell, was that clutch. It affected Auto Stop in that the deck would go into Stop midway through the tape. My solution, or so I thought, was increasing the clutch's spring pressure so it would not slip and therefore not trigger the Auto Stop function. That did work but now this noise has developed.

Do I understand you correctly in that it is the felt disc that is making this vibration? I sure don't envy myself extracting that clutch again to change the felt. I don't suppose those felt discs are easy to come by or make from something are they?

 

[62vauxhall]

The deck might be having a squeal due to the resistance the tape is giving to a belt pulley or slip clutch. It can happen at the beginning of tape and may not be the tapes fault. If you put the deck in play mode and then hold the take-up reel table still it might still do it. The deck if it has a felt disc slip clutch might be too much friction due to the old felt. This is why I put new felt into reel tables on the decks I work on.

Before I go diving into this deck's innards again to remove that clutch felt, I was hoping you could advise me as to what a good substitute would be. I've been trying to imagine what something similar would be used for these days but I'm drawing a blank.

 

[Skywavebe]

Apparently I can not find the service manual on the internet for this deck and so I do not know of the construction of the part you are having trouble with. Some decks are made so that they can not be taken apart, some decks like Pioneer crack and have to be reconstructed with additional brass parts.
The parts in most Teac decks is a matter of pulling it apart and cutting a ring of felt the same size and it is glued in with latex or rubber cement. The felt can be had at any material store and it comes in different colors but the color does not matter because it will not be seen.

Tape decks are assessed by the use of a tape called a MTT160 or other like test tape. This tells you if you have too much take up torque or to little. Usually to much as in 60 to 100 g/cm means the tape will skew and have excessive pull on it. Excessive TU Torque usually has to do with dried felt. It is like the felt on he reel to reel brakes as when dried felt exists the tape can be snapped due to the brakes having no slide as they were when it was new- same situation. Making a spring tighter o a nylon structure usually is not good and is not the solution you need. If the take up torque is low and not providing drive to the tape at any point the result will be dumped tape at the right of the capstan shaft. Then you need to go and examine what the drive parts of the deck for that reel table are.
Commonly I have fond Idler tires that are glazed or cracked, also bad surfaces for them to make contact with such as the reel tables. Then the reel tables and other parts associated in contact with them can also need to be taken off and cleaned and oiled again. I had a Sony TC-K81 recently that was not working because the reel table was binding very badly. After taking it off and cleaning and oil the deck works fine with respect to mechanical function.

If you can provide a picture of the clutch you are dealing with I might have suggestions. There are many little parts that people do not pay attention to that also need oiling and cleaning and after 30 years this will be just about all of them.

 

[62vauxhall]

Yes there is little to be found online about Realistic SCT3000's or the same deck with Metal, SCT3100's. Same goes for it's Hitachi counterpart Lo-D D70S.

This is a photo of the clutch in question:



I replaced all 6 belts and the idler tires when correcting a problem with the auto stop which solved that problem but then I found that the tape would not play completely through before stopping. I determined the problem was that this clutch would slip after about half the tape was on the take up side.

Advice on TH suggested compressing the spring to increase pressure on the felt ring which I managed to do by pressing the top brass keeper plate closer to the nylon pulley. The shaft now protrudes a little past the brass plate's surface and it did work but after a time, now seems to be causing this noise - as in I can feel it vibrating.

 

[Skywavebe]

OK, I see no felt involved with this pulley and so the slip action must either be the belt or some other part. How is the energy transferred to the reel table? Is it possible the belt is slipping on the pulley? Maybe you need a thicker belt that would give more surface area of contact? You know going from .031 to maybe .059".
I also clean the pulley operating surface of any old residue from a belt and that way it has a clean surface.

I did read the first post and there are some Scotch tapes that I have come across that squeal as they are being played and this is the same thing as on open reel tape which was at that time called stiction. But if your deck makes the noise with no tape it probably is the belt slipping. You should also understand that if there are no other slipping surfaces such as a felt clutch and the motor is turning the belt at a fast rate the slipping if at the belt will maybe make noise when high resistance is had- kind of like wheels screeching on the pavement in stop or going of a car. Also if the Nylon part rotates on a metal shaft that might need some oil. I have had intermediate pulley make a screeching sound due to lack of lub on a shaft.

 

[62vauxhall]

The part in the photo is the clutch half I could remove. The pulley is what powers the take up reel with it's underside in contact with the felt ring. The belt driving this pulley is not slipping.

Since I need to remove this again to get at that felt ring, I'll post more concise pictures of both halves.

 

[62vauxhall]

Skywavebe, I finally got to pay some attention to this Realistic SCT3000 yesterday. After my last post, I have put in many 16+ hour days and all I wanted to do during my own time was sleep.

This photo is of the clutch pulley after I compressed the spring so that the take up hub/spindle would continue to turn and not trigger the Auto Stop function halfway through the tape. You will notice that the shaft now protrudes a little beyond the brass disc. I had to "persuade" that disc a little farther up the shaft to increase the spring pressure.



There is a felt disc on the inside of that pulley and that was what was started to slip halfway through a tape causing Play to stop. Increasing spring pressure fixed this and the deck worked properly for a time and then the noise started. I discovered that, with no cassette in place and holding the take up spindle as it's turning, I can feel it vibrating thereby creating the noise.

What that pulley is driving is a rubber tire on the take up spindle. On the opposite end of the shaft is a knurled brass hub that contacts that tire. In this photo. I had the take up spindle off but that brass hub is on the right side edge about 2/3 rd's of the way down. This appears to have good traction against the tire and there does not seem to be any belt slippage. That shaft was removed several times and each time I reinserted it, I applied a small quantity of oil.



What you wrote was very interesting:

"The deck might be having a squeal due to the resistance the tape is giving to a belt pulley or slip clutch. It can happen at the beginning of tape and may not be the tapes fault. If you put the deck in play mode and then hold the take-up reel table still it might still do it. The deck if it has a felt disc slip clutch might be too much friction due to the old felt. This is why I put new felt into reel tables on the decks I work on"

Since I did increase the friction on the clutch, that part caught my attention. I did not yet start disassembly again nor would I want to unless I had something to replace that felt ring with. As you have encountered this problem before, what do you use to replace those old felt clutch rings?

 

[Skywavebe]

I think that when people make adjustments to part of a deck to get them going that these repairs are short lived in that they place a bandage on the problem instead of fixing the cause.
The right way takes more labor and some resources. It can even take some money to get devices that make perfect felt rigs. What I have done is take some of the 1.5mm thick felt I use for brake pads and other things, Place it on a block of wood after measuring what size ring I need and then I hit the Leather punch hard with a hammer. Then when I have a circle of felt it is just a matter of center holing this piece with a smaller leather punch. There might be a tiny bit of trimming with scissors and then the fel ring is attached where it used to go with a little bit of latex cement. Then when I put the assembly together and I oil the bearing where they spin. The deck now works like it should and has reasonable torque as measured by a MTT160 cassette. This can also be seen reducing the cyclic wow that comes from too much take-up torque when the felt dies out. Most people ignore this or do not even know this is happening but if the check the torque with MTT160 then they will find out.
The felt came from a on line supplier and I bought two square yards- I am still using it even after 3 years. A smaller amounts can be found at a material store. The 1.5mm stuff is very common.

 

[62vauxhall]

Thank you. Tomorrow I am going to investigate where I can obtain some felt as you describe. I will then remove the clutch and take measurements of the ring. There happens to be a leather working shop not far from where I live and it seems likely that they could have the right size punches on hand. If so, perhaps they can create one of those clutch rings for me.

 

[62vauxhall]

Finding felt was more time consuming than I expected but I did get a sheet from a (duhh) wool shop. I took a photo of it on edge and next to one of those clutch's from a different model deck but from the same manufacturer. It sacrificed itself in order for me to see how that clutch worked and how it was put together. And that compels me to mention that I have never removed or taken apart the clutch from the deck I am trying to fix. There only seems to be two ways - trying to take off the knurled hub that drives the pickup tire or take of the brass pieces and spring at the other end such as I've done here with the sacrificed one. However it's done, I think I'll only get one shot at it and quite possibly damage it beyond repair during the attempt. If this looks familial and you have a recommended procedure, I'd be very interested to know it. I see no other way to do this other than with the clutch still in the deck.



This is the felt I found and an attempt to compare it to the thickness of the felt ring on the underside of the above assembly.



I hope it does not prove to be too thick and that the felt ring next to it has compressed somewhat over time.

After many phone calls, I located someone who says he has the means to cut rings from felt and I'm going to attempt getting to his shop tomorrow afternoon. I shall take with me the part in the photo for a size reference. Even though it is out of a different model (same make) the pulley's are the same diameter so I'm going to assume that the felt rings are the same. Since they are both from the same make and not too far apart date wise, my hope is that that this part was shared between them.

 

[orange]

Don't you have a decent fabric store like a House Of Fabrics or Jo-Ann? Jo-Ann is great for finding fabrics and craft items.

 

[62vauxhall]

The big fabric stores around here are called Fabricland. While they do have a large selection, even a couple colors of speaker grill cloth, they told me they didn't have felt sheets as I was describing. Also tried the big craft store Michael's but the "felt" sheets I saw there were made from recycled plastic bottles. What I got from the wool shop was what I imagined felt should look like but not having dealt with it for this application before, it could be the wrong stuff.

 

[62vauxhall]

I think I just figured out how to get that clutch assembly out of the deck without damaging anything. It occurred to me that an RC hobby shop would sell something to take gears and pinions off motor shafts and it seems they do. If one of those pullers is the right configuration, I should be able to take the knurled drive hub off the shaft from the front of the deck. That would allow me to pull everything out from the back without molesting the actual clutch assembly while it's still in the deck.

 

[Skywavebe]

I feel your pain. Most of the decks I have worked on did have all nylon pieces that were the ones to come off. Then in dealing with that they would slip off the shaft and then be able to be put back.
On the rare occasion that I come across stuff that can not be taken apart but the felt can be cut and removed. It may be possible to sneak a round donut into the assembly and doing so with a cut that then is joined together when the part is glued to the base where it goes. This is more time consuming but will with the right hands still make a world of difference.

f the brass keeper is taken off and there is no other way, then it might be damaged to where it does not go on anymore. So in that case one would have to figure out another method of retention on that shaft. That might be in the form or C clips or maybe a E clip if you have one the right size.
The other possibility is position something for the retention purpose and clean the shaft with alcohol and apply Some JB Weld to fix the washer or whatever you have on there. You won't be having to deal with it again and if so from the other side as you have tried. Some of these tape deck solutions are a lot more complicated that some people thing "with just a belt".

 

[62vauxhall]

How right your are. I just got home with the singularly last puller in stock from the only RC store I found who sold them and immediately tried it out. Although a good idea, the metal it's made from is too thick so I cannot insert it where it needs to go.



And right again you were that removing the brass keeper (as you so fittingly described it) is the only way to get at that felt ring. There's no way I can get the the knurled drive hub off as I thought I might.



Sensing that was the case even before I read your post, I pried off the keeper with something called a Richard Roofing Knife - truly one of the most useful things I have ever bought. I was able to pry it off incrementally and am pretty sure it will go back on again. So what I'm left with is this....



My thought now is to remove the old ring with an Exacto, Olfa or razor blade. To remove the residue I would try a solvent of some kind, alcohol or perhaps lighter fluid, which would hopefully soften it enough to wipe off or scrape off.

I have yet to meet the fellow who says he can cut the needed ring from the felt I have. From the photo in my previous post, are you able to comment on whether it is suitable or not?

BTW, this is that Richardson Roofing knife. It's not razor sharp (but I have been cut by it) and it's very stiff so can tolerate a lot of force without bending or disfiguring. I got it initially to pry some drivers out of speaker cabinets that had adhesive instead of screws or bolts. It worked a treat for that and literally dozens of things since.