CPC 464 tape - weird speed problem

[Bryce]

The belts actually look fine, but there's a lot of dust in there. Give the pcb and metal parts a clean with a small paintbrush (Pinceau). The head definitely needs to be cleaned and the pinchwheel, it's in a serious state. The cogs definitely need grease too. I suspect that will solve your issue.

Bryce.

[itneb]

 Thanks Bryce,
I'll do that after bought the required tools.

The belt has been replaced three months ago so it is pretty new.
I already used sand paper on the pinch wheel. Can i do it again without damage it? at worst case, can it be easily replaced (where to buy a new?) ?

About the head (not the erasing one) , i am a little surprised because i cleaned it with isopropyl alcohol  and qtip (coton tige) recently (I have even accidentally erased upper parts of the serial number of the head).

[Bryce]

[attach=2]

That there looks like either a scratch across the head or a "dirt-track". Try scratching it away with something plastic. The alcohol and cotton bud obviously weren't enough to remove it. The side with the serial number doesn't need to be cleaned, just the side that contacts with the tape.

Bryce.

[itneb]

ok you are right i had not seen it on the photo! 

i'll confirm it when i'll give it a service.

[Velktron]

That head looks like it has been well-used! The material on the tape path has worn out somewhat, creating a recessed groove. That's not a problem, until the wear becomes too much and then the tape becomes hard to keep in alignment. Even further wear, and the head gap open (a normally invisible tiny vertical line in the middle of the head, separating the two magnetic poles). When that happens, it's noticeable because the head permanently loses HF response.


For the rest, I'd say lube the mech, but I'll have to disagree with Bryce on the use of vaseline or other mineral-oil based grease on plastic parts. In any case, try removing as much dirt and old lubricant as you can with a bit of alcohol, before relubing. Also, I'd relube only the axles of the cogs, not the teeth of the cogs themselves. Those, just make sure they are clean and free of dirt and debris.

[itneb]

That head looks like it has been well-used

I own this cpc since 92 (or 93 ?) and it was already a second hand!
As I said the problem exists since many years (maybe 98/99  ?). At the time i was not aware of others guys who still use cpc's and did not imagine to repair it so the workaround was to rewind and retry to load when read errors occured. So the player had more activity than it should have! (I mostly use a car/jack tape adapter now.)

About the head, i'll try to recover the "dirt-track" as recommended by Bryce. But i don't think  it's a big issue for now because when the speed is accurate the loading works pretty well.

So, i've bought the weapons today:

* Silicone lubricant (the same than the link of a previous post)
* Vaseline oil
* Contact cleaner in spray
All of the same maker "3-in-1"

* Some small paintbrushs
* A medium toothbrush

To summary what you adviced me i must do:

* Use toothbrush on the teeth of the cogs (in the front of the mech and in the rear behind the "wheels")
* Clean from dust as possible with paintbrush the mech and the pcb
* Deposit some silicone lubricant on the axis of the cogs (in the front only because the axis of the wheels dont seems to be easily accessible)
* Deposit some silicone lubricant (or vaseline?) on the metalic moving parts
* Use contact cleaner on the microswitchs (is it the thing linked to orange/red cables which is visible on the photo of the rear of the mech without pcb?)
* Sandpaper on pinch wheel
* Try to remove 'dirt-track' and use qtip + isopropyl alcohol on the heads.
* Give a try
* Deposit lubricant on the cogs if the issue remains.

I'll wait a little before for advice before starting the surgery !

[Bryce]

Sounds good to me. Yes, the micro-switch is the bit with the red and orange wires. The surface on the inside of the two metal strips is where the cleaner needs to be sprayed.

Bryce.

[itneb]

So the service is done.

Regarding to the main speed issue it seems stable but it is hard to say for now.

Furthermore, the issue showed at the very first tests after the service. I had to wait some minutes before it disappear. After that it not occured. Maybe the lubricant needed to 'spread' (not sure about this word in english) a little inside the center of the cogs?

The good points:
The controls buttons (play,stop,ff,rew etc.) are really smoothers and it succeeded to load two games which usually fails to load.

Unfortunately, i still have 'wow' problems on mid/long duration tapes. I'm pretty sure the problem come from the pinch wheel. I reused sand paper on it but had no significant effect. I suspect it need to be changed  (i noticed it performs well when it is slightly damp).
Any advice about this?

[Velktron]

Not much to say at this point, other than changing the pinch roller. However, it's not as easy compared to the service you already performed. For one, you have to find one of the correct dimensions, and new/fresh enough not to have suffered the same hardening effect.


If the pinch roller hardens or otherwise degrades, then no amount of sanding or treating with chemicals will be able to save it permanently. You might try cleaning it with some acetone (yeah, acetone, not alcohol) after you have filed it it. This will melt and recondition some of the surface rubber for a while (the Q-tip you'll use will blacken a lot  )


Other chemicals to try: naphta, white spirits, typewriter cylinder treatment fluid (which is really a mixture of naphta spirits). I prefer acetone because it's less oily and acts faster. However, please understand that these treatments are just temporary, and sooner or later you'll have to repeat them.

[Bryce]

Also, don't try it with a tape until the acetone has completely evaporated!! Otherwise you'l destroy tapes.

Bryce.

[itneb]

You might try cleaning it with some acetone

I'll try this AND wait before using some good olds original game tapes!
I have some old C60 cassettes with tape a little damaged or without anything relevant on them. I'll play them from start to end two or three times after waiting a night..

About the original issue i'll wait to see if it will resists the test of time but for now it did not occured. Overall the tape drive performs better.

So many thanks to @Velktron and @Bryce for your help and sharing such knowledges it is very nice.

[itneb]

Finally i got it!  :

The apparent good condition after the service was unfortunately a false hope. The problem started to reappear two days ago and was persistant to the point i was unable to load anything — the speed problem being triggered every two minutes at best.
This started do drive me crazy. After observations of the mech performing and some experiments on it i came to the conclusion the problem was the motor: I tried to run it without belt and the noise i mentioned in an earlier post remained and worst: it was doing strange "clac clac clac" noises. (maybe an axe issue ? or something broken inside the motor, i don't know)

So i decided to desolder the motor and replace it with the motor of my other CPC 464 keyboard. It works like a charm now, and is really less noisy.

I resoldered this apparently broken motor on my other cpc keyboard too. The problem is now triggered by this keyboard — it's even worst — which seems to prove that the problem was the motor.

Now i need to take look at `acetone` on the pinch wheel to definitively get ride of my tape drive issues but i'm on the way!

[Velktron]

I think that possible motor axle lubrication issues were mentioned at some point (I have a Luxman deck which had this issue in its main motor, and it actually squealed and howled horribly when it slowed down    ). In my case it was "enough" to lubricate one of the motor's two bearings (I say "enough" because reaching the spot without major disassembly was impossible, so I had to use a VERY thin syringe nozzle laden with oil).


But it the bearing is worn and gone, adding a drop of oil won't save it, so perhaps completely replacing the motor was the best course of action in your case.

[Bryce]

Finally i got it!  :

The apparent good condition after the service was unfortunately a false hope. The problem started to reappear two days ago and was persistant to the point i was unable to load anything — the speed problem being triggered every two minutes at best.
This started do drive me crazy. After observations of the mech performing and some experiments on it i came to the conclusion the problem was the motor: I tried to run it without belt and the noise i mentioned in an earlier post remained and worst: it was doing strange "clac clac clac" noises. (maybe an axe issue ? or something broken inside the motor, i don't know)

So i decided to desolder the motor and replace it with the motor of my other CPC 464 keyboard. It works like a charm now, and is really less noisy.

I resoldered this apparently broken motor on my other cpc keyboard too. The problem is now triggered by this keyboard — it's even worst — which seems to prove that the problem was the motor.

Now i need to take look at `acetone` on the pinch wheel to definitively get ride of my tape drive issues but i'm on the way!

Then the motor brushes must be on their way out. You could always try changing the brushes? Nothing to loose?

Bryce.

[itneb]

You could always try changing the brushes? Nothing to loose?

I've never done this kind of thing before nor i know what is a motor brush exactly! But I'm ok to try as i have nothing to lose. but how to ? do i need to disassemble it ?

(I say "enough" because reaching the spot without major disassembly was impossible, so I had to use a VERY thin syringe nozzle laden with oil).

Many can i try this before. If i understand i need to pass a little of oil through small spot holes ? what kind of oil ?

[Bryce]

I've never done this kind of thing before nor i know what is a motor brush exactly! But I'm ok to try as i have nothing to lose. but how to ? do i need to disassemble it ?

Brushes are two contacts that bring the voltage to the rotating core of the motor, so they are being worn away all the time. The picture here shows them quite well: https://experimentalev.files.wordpress.com/2011/03/dc-motor-parts-6.jpg  At some stage they are through from years of friction. Unfortunately they're not a standard replacement part, so you would need to find a very similar motor to borrow the brushes from.

Bryce.

[itneb]

It seems a bit complicated! Maybe i will look at it someday...But for now i will enjoy the one repaired!