Philips N4414 tape deck clicking capstan.

[ALEXANDRAPALACE]

The recorder plays and records well, in fact excellent, no issues, everything functions. Has new belts and alignment.
Problem is the idling capstan when deck is switched on produces a rubbing/light clicking noise as it spins which is annoying. I would expect some very faint noise because it's on all the time, but this is distracting and either indicates
#wear in some part
#need for lubricant (I thought they were self lubricating)
#something rubbing against a rotating surface

Before I swing open the top to inspect is there any suggestions what I shoud be looking for?

It's a three motor machine so presumably the capstan has its own belt and motor.

Before I can go forward and really enjoy this machine, because the sound is impressive, I need to fix this.

Cheers David

[Sideband]

Well the first thing is that you said it had had new belts...that implies ALL belts? Then further down you say 'It's a three motor machine so presumably the capstan has it's own belt and motor'. It does indeed but presumably you would know that if you had changed all the belts? If you didn't change the belts then it would certainly be worth checking the capstan belt. However also check the counter belt. The counters can stick and cause a regular ticking noise so just make sure the counter is actually working. To prove the point just unhook the counter belt and see if the noise stops. Otherwise the capstan belt might be twisting as it turns (although that probably wouldn't be loud enough to be disturbing). These were pretty quiet machines 30 years ago but with bearing wear etc......

[ALEXANDRAPALACE]

Hello Sideband, the belt replacements were carried out by a tech who said all the previous belts had perished into that tarry mess. He cleaned it all up fitted new belts and did some work on the tape heads and record. I think I trust him in that department. Probably the fault will become apparent when I look inside. I will certainly check the capstan belt and counter which is working smoothly. The noise is definitely coming from the capstan drive not the counter. Thanks for your interest. I've got to say I'm reluctant to post it back or anywhere due to the somewhat negligent way parcels are treated nowadays and the fact it is fairly fragile. I'm sure there's a mechanical problem and a fix not requiring the sort of electronic expertise or experience with tape decks I totally lack.

[DMcMahon]

David did not say he had changed the belts himself, so maybe he has recently purchased the recorder and was told by the seller that it has new belts. if the noise only occurs during capstan idling then it will not be the counter.

David

[ALEXANDRAPALACE]

Hi DMcMahon, thanks for taking the trouble to help. I had the machine serviced with new belts and alignment plus checking. When it came back through the post there was evidence it received a "bump" as a corner of the perspex lid had been broken off. However (being Philosophical about that) the rest of the machine functions extremely well with strong recording, wind and rewund, excellent playback. There is just this annoying regular tapping and brushing coming from the caostan ad it is spinning in the background - most noticeable of ciurse when there is no music playing and it is just idling. I do have a donor machine which has already offered up its pladtic On/Off button. Anyway I will open it up tomorrow - these units are built for servicing with just fiur screws - and probably come back with more Q. s!!! Hopefully with photos if I am allowed to upload as a newbie.

Just when I thought I was out, they drag me back in.

[Sideband]

I seem to recall that there are brushes (little brushes with nylon 'hairs') arranged to press gently against the capstan belt presumably to discharge static that might build up. They also collect muck and grease over the years so it might be a good idea to check them. I was never quite certain why they were fitted but manufacturers seldom, if ever, fit parts that don't have a function.....

[Michael Maurice]

What is the frequency of the ticking? Does it change when you change speed?

There cant be much causing this sort of fault. One thing you can do is remove the capstan belt and check that there is no goo left on either the flywheel or the motor pulley.

Spin the flywheel by hand to see if the ticking noise is still there.

One other thing, check the distance between the tacho and the flywheel, if the tacho is too close, it might cause this.

[Andrew2]

A nicked belt can cause this as the nick passes the discharge brush.

[peterpiper]

Hi David, I had a similar problem on a similar but not the same Philips recorder. Mine was caused the short earth link on the motor being broken. the motor is rubber grommet mounted so has to be earthed via a short link. This was broken causing static build up and arcing every 3 seconds. As was suggested, check the little brush that rests on the belt first. Took me a whole day to find it !
Peter

[ALEXANDRAPALACE]

Thanks for all this advice Sideband, David, Michael, Andrew, Peter and Maurice!
I am now armed with a few pointers and things to look out for when I go into the cabinet.
Incidentally, the rate of the clicking does increase with the speed setting so it is obviously related to a mechanical part.
Cheers, as with all things choosing the time when I have enough patience and concentration to start looking.

[ALEXANDRAPALACE]

The capstan motor is OK, I unhooked the belt and it just has a very soft whirr.

The issue seems to be coming from the other end with the flywheel under the capstan. That's definitely where the clicking is coming from.

One thing that struck me was the tightness of the capstan belt (they all look new) it goes on OK but it's a lot tighter than the drive belts to the spindles. I'm wondering whether this is the cause of the noise. How tight are capstan belts supposed to be?

Dismantling would require unscrewing the capstan from the top or accessing through the back. If it requires lubrication. how does one access the bearings?

Are there any thoughts about this?

Cheers David

PS I hope these photos help.

[ALEXANDRAPALACE]

I think I've pinned the problem down. The capstan belt rides up and down on the nylon capstan pulley about 3/8" or 4-5 mm. As it does this it performs a couple of bumps which creates the regular Da dah type of click I'm getting.

I've lubricated the pulley bearing with some 3-in-1 oil on a very fine artists paint brush taking extreme care not to touch anything else. Also around the top of the capstan spindle avoiding the bit that makes contact with the tape.

I'm quite sure that the capstan motor is OK, the bearings on the capstan pulley are OK.
That leaves the belt itself and the pulley surface.

As the pulley is nylon it seems unlikely there is any wear or defect on that. That leaves the capstan belt.

It certainly has a firm tension - but that might be normal and I can't tell. Visually it looks OK with no nicks or defects though these tape belts are like thin strings. I tried reseating it on the motor and moving it on the pulley but it ALWAYS returns to a position where it is moving slightly up and down. These efforts have reduced the sound by about 50% which for me is acceptable.

The only thing is while I have identified the problem and mitigated it, I made the ght close up the deck reconnect it all again in the upright position which I prefer and it might come back as bad as before!

I would prefer to know that I have fixed the problem rather than just put it back and hope for the best?

Any ideas about the belt riding on the pulley without changing it (which does not look easy) would be most gratefully appreciated. Here's the thing. Do new capstan belts start a little bit tighter then work in after hours of use - a bit like running in a car engine? Especially on a vintage 45 year old machine?

Cheers David

[Station X]

Originally Posted by ALEXANDRAPALACE

I made the ght close up the deck reconnect it all again in the upright position which I prefer and it might come back as bad as before!

Cheers David

[Michael Maurice]

The belt should not be over tight, you will damage the motor bearings if you carry on using it. I don’t think you’ve cured the fault, merely masked it.

[ALEXANDRAPALACE]

Trouble is I have no experience of these belts other than Philips and other record turntables. There is a tighter tension on the capstan than the spindles both of which "feel" exactly right. This capstan belt is a lot firmer than the turntable belts I'm used to but then it's different shape. Really have no idea. Is changing the capstan belt a complicated job...?

[Andrew2]

Ah, something is ringing a bell. Is this a flat, square or round belt? I've had square-section belts do a quick twist as they pass over a certain idler or pulley. IIRC, it is down to the belt being fitted with a twist in it or being too tight. Gosh, can't really remember. The sound is quite a sharp click.

[Sideband]

It's over 40 years since I serviced these at Philips. It looks like the capstan belt fitted has a round profile. It that correct? It should be a square profile. That could be the problem since there is no corresponding groove in the flywheel. If it's a round profile it might 'ride' up and down the flywheel, twisting as it goes. The square profile belt lays flat on the flywheel and 'self-centres' when the flywheel runs so that it lines up with the motor pulley. You might have to find a square profile belt. I'm almost certain there are belt kits available on eBay but you might have to get them from Germany.

It's very easy to change the belt. There is a bracket over the flywheel held to the chassis by two screws. Loosen one and unscrew the other and move the bracket to one side (or you can remove it altogether if you prefer) then just unloop the belt from the flywheel and motor. When the new belt it in place, just refit the bracket....no alignment or adjustment needed. The belt (assuming the correct one) will centre itself when the motor starts to run.

It shouldn't feel tight.

[ALEXANDRAPALACE]

Hi, thanks Andrew and Sideband for narrowing it down.

The counter belt is a square profile, but it is much longer and looser than the capstan belt so there hasn't been an obvious mistake, it's correct to the counter.

The three other belts including the culprit are round. Examining the flange on the capstan motor it looks if it could accept a square profile belt. As for fitting - I can see the bracket you describe, but accessing the screws that hold it either means some dismantling which given the complexity of these parts I cannot do. Unless I can access it through the back of the machine. The photo shows the bracket screw I think you are pointing me to tucked behind the yellow cable. The screw head is at the bottom so you need to get to it somehow.

Incidentally, did you work at CES for Philips in Purley Way Croydon? They fixed the blown power transistors on my 521 amp under warranty in about 1973.

[Reelman]

Many reel to reel recorders that relied on belts often used square section ones. These, particularly as they were quite long seem to be unavailable now so a round section belt is substituted by the suppliers. Therefore there is a compromise being made.
The brushes that Philips often fitted in the path of the belt I always thought were to stop the oscillation that could happen by the belt.
On the N4450 static could be a problem especially with 10.5” reels during winding and sparks could be seen in a darkened room jumping from the reels to the metal work with a loud crack. The main drive belt certainly had the brushes and I think also the winding belts.

Peter

[unitelex]

Originally Posted by Sideband

I seem to recall that there are brushes (little brushes with nylon 'hairs') arranged to press gently against the capstan belt presumably to discharge static that might build up. They also collect muck and grease over the years so it might be a good idea to check them. I was never quite certain why they were fitted but manufacturers seldom, if ever, fit parts that don't have a function.....

These brushes might be for static discharge as you say, but I also noticed on one machine (maybe not a Philips) that if the brush was removed then the belt started vibrating, effectively resonating like a bow string. This vibration stopped once the brush was back in contact. So this could be another justification for the brushes?