464 Cassette Problem

[corgi74]

Hi


Just bought a 464 and everything seems ok except it won't play tapes. It will rewind and fast forward perfectly but when I play a tape the right and spool moves about 3/4 of a turn and then stops. The left hand one keeps moving causing the tape to come out.
I've opened it up and the belt seems ok but obviously it may have stretched.

Does anybody know what this might be please and is there something you can recommend?  I'm hoping it is the belt and have ordered a replacement.


Thanks.

[Velktron]

The tape in almost all tape machines is not actually pulled by the spindles: it's actually being pulled by the capstan + pinch roller (that steel shaft and rubber wheel near the heads) at constant speed, while the right (takeup) spindle, the one that's supposed to collect the tape before it becomes tangled, gently  pulls on the tape with a slip clutch, at variable speed, to prevent spillage or "tape eating". The left spindle (with the supply reel) isn't actually powered during playback, it merely provides backtension for the take.

However, the capstan and takeup spindle are often powered through different means, and one of them may fail separately (usually the takeup spindle). When this happens, the machine will "eat the tape".

This happens a lot in mechanisms that have a separate rubber belt for the takeup spindle in playback mode. There's a big belt connecting the motor to the flywheel (the big metal wheel which also rotates the capstan), and a smaller rubber belt connecting the flywheel or another part of the mechanism to the takeup spool. If the big belt fails, nothing moves. If only a secondary belt fails, just the spindle won't move, but the capstan will still be able to move, pulling tapes and causing them to be "eaten".

The reason that the spindles can still turn in FF/RW but not on playback is that in those modes, motion is usually transmitted directly from the flywheel to the spindles through a set of gears, while on playback a slip clutch driven by a secondary belt or idler is used. If that belt or idler fail or lose their grip, you will have "tape eating" problems.

TL; DR version: look for a smaller belt connected to the takeup spool but NOT directly connected to the motor, and change it.

[Kevin Quinn]

Thanks ever so much for your reply. I appreciate your help.
I was unaware there were 2 belts in the 464 cassette deck.
Where would I get the other one as I can only find the main wheel belts online.


Thanks in advance

[Kevin Quinn]

Just had a look at the manual for the cassette deck and it only has one belt.


http://www.grimware.org/lib/exe/fetch.php/documentations/hardware/amstrad.cpc/manuals/service.manual.cpc464.ctm640.gt64.pdf

[Velktron]

Well, if it doesn't use a secondary belt, then there must be a rubber idler or a similar secondary mechanism (different than the one used in FF/RW) to move the takeup spindle. Both belts and idlers can harden, crack, wither away or even just melt and turn to a black, tarry goo.

In any case, you must either replace or recondition whatever it is that the CPC's mech uses.

By looking at the diagram linked to by Kevin Quinn (on page 5 of the SM), i'd be looking at part No 20 "idler assembly": it's not clear by the diagram if it has a rubber surface. How is motion transmitted to the takeup spindle when in playback mode? N.B. that there might be several different versions of the tape mechanism, with differences in the transport's detail.

What happens if you just push play with the tape door open? Does the spindle turn then? Can it be stopped very easily by hand? It should be able to offer some resistance against e.g. being casually touched by a finger, but not stop completely at the slightest touch, nor should it turn at full force like in FF/RW (that would indicate a worn slip clutch). By gripping it firmly, it should cease rotation (but with some force felt through it) and resume spinning when released. If not, then you have a weakened idler, OR a slip clutch that has failed and can't transmit torque (that's actually part of the spindle).

The main capstan itself should be nearly impossible to stop by hand/finger pressure, unless the main belt is severely weakened and/or slipping.

I have a Sony FM-1 Walkman that had a similar problem (weak takeup spindle) and also used no secondary belt, but a rubber surface on one of its idlers. The solution, in my case, was to clean the rubber with white spirit, and let the walkman in playback mode WITHOUT A TAPE for several hours: that reconditioned the rubber surface enough to restore normal grip.

Edit: the tapehead in me can't resist: here's a photo of the tape mech used in the Schneider 464:



It seems that the small black wheel (the idler) also takes motion directly from the belt, but it's not clear how it transmits motion to the spindles.

And the one used in the 464+, which looks much more like a cheap boombox's, and uses two belts like most cheap boomboxes did. Ugh.



What's interesting is that the SM says that a 4% speed variation is tolerated (!). Compare that to audiophiles/music use, in which even 0.1% is annoying. This means that you could even use a common rubber band as a belt replacement.

[Kevin Quinn]

Thanks for all your help. I've ordered a new belt so I think I'll give that a go for the sake of £2. The belt on there at the moment doesn't feel super tight but I have no reference to compare.
I've also order a tape to 3.5 jack adaptor as a backup if that doesn't work. I can still use it for MP3 and WAV files so no loss.
When you get offered a CPC for £40 with a colour monitor you say yes and then worry about if it works.

[Velktron]

The belts used in tape decks are very special: they are made from neoprene or specially cured rubber, and are not supposed to stretch or "hang", nor to be installed too tight: they must be just right. They normally last for years, whereas a normal rubber belt decays in just months, however they eventually do fail too, in various ways (getting too soft/too hard/breaking/melting/stretching/falling off).

The belt used for moving the flywheel and capstan (in many decks, it's the only one) is particularly critical: it must drive everything at just the right speed and within speed tolerances, otherwise the sound will be very wobbly and bad. Belts used for secondary purposes (e.g. driving spindles or counters) are less critical, and you might get away with a rubber band,if a proper replacement isn't available.

It takes some experience with tape transports to determine what's wrong, but the main killer is often a combination of worn/missing belts and failing idler mechanisms, plus, depending on the mech's  design and age, there may be other things that can go wrong. Have you tried the spindle playback force test I suggested?

[Kevin Quinn]

Yes mate. The spindle was moving. I could slow it down by touching it with a little force and had to push quite firmly to stop it but I could feel a vibration in my finger like it really wanted to start turning again.
I'm assuming this is a good thing?

[Bryce]

Give the little rubber wheels a decent scrub with some mild sandpaper and it should be fine. If the belt is relatively tight and springs back when you stretch it, then you don't need to change it.

Bryce.

[Kevin Quinn]

Just had a quick try with an emery board and it now does a full turn before it stops so there is definitely more resistance there. Probably need to use a stronger paper.
I think another rub and a new band might sort it out.
Thanks Bryce and Velktron.

[Bryce]

The surface of the roller should be matt and not look or feel smooth or shiny.

Bryce.

[Velktron]

Let the deck "exercise" for a while (put it in playback mode without a tape in it), until it can sustain rotation (not just 1 turn) indefinitely. Also clean up everything in the tape path that comes in contact with the tape (erase head, R/P head, pinch roller + capstan, auto-stop arm) with cotton swaps and denatured alcohol or IPA.

About the spindle resistance test, also try pushing the spindle up/down on its axle. It should pull harder when pushed down and it should spring back to its original position without getting stuck or frozen. Also, the force you're feeling when blocking its rotation should be smooth and continuous, not bumpy nor with excessive "dry" vibrations.

You haven't specified if the tape deck ends up "eating" tape if you leave it on its own. If so, then it's a takeup spindle problem. If the tape completely stops moving after a turn though, then the problem might be somewhere else, like a worn or slipping pinch roller. Check for dents or excessive glossiness/hardness of the rubber, causing poor and intermittent grip. Sadly, I've seen a lot of tape decks which were left in a "play" position for years, and ended up permanently denting the pinch roller, rendering it all but useless. If it's dented or hardened, no amount of sanding or chemical treatments can restore it to fully functional status, at least not for long, and a replacement is always a better option.

[Kevin Quinn]

If I leave the tape in while it's playing it does chew the tape up.
I'm going to leave it running in play for a few hours and see what happens.

[Kevin Quinn]

Got a new belt an put it on but no change unfortunately. Even worse is the pause lock plate assembly pinged off and went flying across the room so now it won't pause.
Hopefully this shouldn't affect me using a tape adaptor which was the initial plan.
Just would have been nice to play the games I got with it.

[Bryce]

If you can't get the deck working, send it over and I'll service it.

Bryce.

P.s. Don't send it with registered Royal Mail! (ask Neil79 why)

[Kevin Quinn]

If you can't get the deck working, send it over and I'll service it.

Bryce.

P.s. Don't send it with registered Royal Mail! (ask Neil79 why)

That would be great thank you. I'll see how I get on with the tape adaptor but I would prefer it to work properly. Does the missing pause lock assembly matter?

[Kevin Quinn]

I need to speak to neil79 too! Lol

[Bryce]

I don't think I ever used the pause button except for some multi-load game that didn't bother stopping the tape between levels through software (can't remember which one it was). You can easily live without it, but if you find the parts, send them over too and I'll repair that too. As you intend mainly using an adapter it becomes totally useless as the external player does the pausing.

Bryce.

[Kevin Quinn]

The saga continues...


My tape adaptor arrived and so far I've got nothing to work. I'm using tap dancer and so far Gryzor, Renegade, Arkanoid 1 and 2, Donkey Kong and BB4CPC have all failed to work.
Revenge of Doh even turns the monitor off!
I'll keep persevering but I'm not enjoying CPC ownership so far. 

[Bryce]

The volume is critical, try turning it up.

Bryce.

[Kevin Quinn]

That was full blast. I was using my Nexus 7 is airplane mode. Tried it with the sound down and it wouldn't load block 1.
Going to have a proper play with it over the weekend.

[260Z]

That was full blast. I was using my Nexus 7 is airplane mode. Tried it with the sound down and it wouldn't load block 1.
Going to have a proper play with it over the weekend.

Hi Kevin [emoji3] , and welcome.

I feel your frustration.  I very recently picked up a 6128 ( while I wait for a decent 464 ) and I've had similar issues regarding the loading of cdt's.

What I have discovered is that many modern electronic devices seem to detect the cdt wave as noise and therefore attempt to process it. In the process destroying the data signal.

I tried unsuccessfully for days to load a cdt using a laptop , but what I discovered is that I could actually hear the computer muting and changing the sound. When I switched to a desktop computer , turned all the reverb effects ect off , hey presto !

And to emphasis this , I picked up a $5 Sony Walkman from a pawn broker and it works perfectly with the physical tapes.

Hope this is some help [emoji4]

Cheers,

Robert

Sent from my GT-I9305T using Tapatalk

[EgoTrip]

The volume is critical, try turning it up.

Bryce.

I found lower volumes got better results, if it is too high it will clip and distort the signal. Also, my tape deck (its a multitrack recorder) lets me output in MONO, so I have just the right channel playing then hit the MONO button, and I get the best results with this for both physical tapes and CDT's.

[pelrun]

Also Tapdancer has been really flaky for me, and in my opinion the UI is awful. I've had far more success converting the CDT's to WAV files and playing those from my phone instead.

[Bryce]

I found lower volumes got better results, if it is too high it will clip and distort the signal. Also, my tape deck (its a multitrack recorder) lets me output in MONO, so I have just the right channel playing then hit the MONO button, and I get the best results with this for both physical tapes and CDT's.

Yes, it will all depend on what you are using to play the cdt. Some devices are generally very low volume so they need to be turned up. A normal PC would probably need to be turned down.

Bryce.