Hi all,
Because this is my first post, i introduce myself quickly.
I'm a french (sorry if my english isn't very good!) part time cpcist since my childhood, rediscovering the joy of using a CPC from time to time.
The tape drive of my Schneider CPC464 has a weird speed problem since years which i never managed to resolve:
It performs well for some times then the speed starts to decrease progessively during some seconds to a point where loading errors appear, stay more or less at this speed a moment with 'wow' effects then returns to normal speed in a more or less aggressive way leading to read errors if not already appeared before.
During this 'speed problem' event the mechanism become a little noisier. If a press REW of FF during this event, the rewind/fast forward performs slower than normal too. Even without tape inside i recognize if the drive performs at accurate speed or not by earing the noise.
It is unpredictable when this problem is triggered. Sometimes it does not occurs during several hours, sometimes it is triggered very often. The duration of this event varies but is rarely longer than one minute.
I managed to capture the problem on video, The problem starts at ~2:40 and finishes à ~3:00:
Things i have already done (thank to other topics of cpcwiki):
- replaced the belt
- cleaned heads/capstan/pinch roller with qtip and isopropilic alcool
- used sand paper on pinch roller a little (this partially resolved some wow effect i have on long duration tapes but it is unrelated to this topic)
- tested a looot of tapes (short and long duration).
- rewind tape before play does not resolve the problem as it appear even without tapes inside the deck.
- tested with tapes locked inside the door or bypassing the door.
I can't figure which part of the mechanism is responsible. Can it be electrical ? the motor is dead?
Thanks in advance.
Does it makes the sound on all tapes, or only on some ?
Because some crap cassettes can lead to that, i had some which were doing this on my very modern tape reader.
It does this on all the tapes (I have ~50 tapes)
If i swap the tape with another during this `speed decrease event`, the issue remains.
Furthermore, even without tape, by earing the noise made by the mechanism and by watching carefully the `takeup reel` (? i'm not sure of the name of this i mean the right thing that turns when playing without tape) i can see that it doesn't turn at the right speed.
or the power is unregular in it's arrival in the motor.
Mhhh..... maybe again capacitors problem ?
I have really poor knowledges in electronics. Can this be checked using a multimeter (i have a really cheap one) ?
I have another cpc464 keyboard (an amstrad one) which is not in good condition, it has others tapes problems (pinch roller dead) but not suffers from this speed issue. Could i cross check with it or simply use it for spares ?
@itneb (http://www.cpcwiki.eu/forum/index.php?action=profile;u=1501)
Spool the tape to the end.
Rewind tape, and then try again.
Some times the tapes get slightly folded over and scrape on the plastic.
and/or ONE very small drop of lubricant on the Capstan (Metal shaft that rotates) bearing ONLY ONE Small Drop.
Then clean the Capstan of any excess oil.
Good luck Ray
Other things to check:
Can you easily turn the tapes by hand? Are they too stiff or too tightly wound? This may indicate excessive takeup torque, due to a stiffening takeup spindle clutch.
Do the tapes leave some kind of sticky residue on the head (if light brown or white, it's a binder breakdown problem. Worse still, it's "contagious" between tapes, if the tape path is not cleaned thoroughly.
In the CPC tape mech, motion to the takeup spindle is transmitted via an idler. Is it worn/irregular?
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Spool the tape to the end.
Rewind tape, and then try again.
I do it all the time, even with other decks (i have an old Toshiba walkman) but this don't solve the problem.
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and/or ONE very small drop of lubricant on the Capstan (Metal shaft that rotates) bearing ONLY ONE Small Drop.
Then clean the Capstan of any excess oil.
I'll try it. What kind of oil/manufacturer can i use ?
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Can you easily turn the tapes by hand? Are they too stiff or too tightly wound?
Yes they turn easily by hand (before and after use with cpc) and play nicely with the walkman.
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Do the tapes leave some kind of sticky residue on the head
I have never found this kind of residue. The pinch roller was a slighty brilliant brown but i cleaned it.
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In the CPC tape mech, motion to the takeup spindle is transmitted via an idler. Is it worn/irregular?
it's difficult for me to ascertain but i think it's ok. Here is a photo of the mechanism i took when i unskrewed it.
[attach=2]
I can unscrew it again to take others photos if this can help.
I would like to see the underneath of the unit -exactly how motion is transmitted from the capstan/flywheel (which has a constant, controlled speed, at least that's the intention ;) ) to the takeup spindle (which has a variable speed depending on the tape's position, and thus uses a slip clutch).
There are several methods this can achieved and there are numerous tape mech patents (e.g. contact idlers, permanent gearing, a secondary rubber belt, or direct/indirect drive by a secondary motor, in luxury tape decks) but the CPC464 service manual doesn't make it very clear which is actually used, so a photo of the underside of the tape mech would be useful, with emphasis on the critical details of how the takeup spindle is powered.
In any case, are those gears that appear on the upper side used during playback? In old boomboxes with a similar mech, those gears can stiffen, and require disassembly and some lubrication.
(EDIT: by looking at the pic carefully, it seems that during PLAYBACK, motion is transmitted from that rubber-coated idler in the middle of the mech, to the ribbed upper part of the right spindle, which then pushes on the lower portion through a felt clutch. In FAST FORWARD mode, motion is transferred to the LOWER part of the right spindle directly, using the the gear above the idler, which makes it spin harder and faster. Is this correct?)
As for lubrication in general: for the capstan bearing you can use a drop of any light machine oil (e.g. Singer sewing machine oil, 3-on-1 general purpose DIY oil etc.), the best technique for applying it, other than disassembling the unit and removing the capstand and flywheel, is to put the unit in playback/pause mode, and let a drop seep down into the bearing, by applying it directly to the spinning capstan.
For plastic, rubber or metal-on-plastic parts such as gears and spindles, things are a bit more complicated. You cannot use any mineral-based oils or grease there, because they break down plastic parts and cause worse problems on the long run. Only silicone-based lubricants are compatible with plastics, but they are harder to find.
Finally, another possibility to look into, is the motor itself. It also has bearings that can dry or wear out, causing speed fluctuations (usually works OK for a while but then loses speed suddenly and for a few seconds at a time, sometimes even squealing).
Wow! What an answer! Thanks Velktron
I'll take time this week to unskrew the tape mech, take photos/videos of the parts you asked and post them here.
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usually works OK for a while but then loses speed suddenly and for a few seconds at a time, sometimes even squaealing
It sounds a lot like my issue and seems to be more accurate than a gear/dry issue because it is observed regardless of the 'mech position' (PLAY/REW/FF ...) but i may be wrong!
If it happens in all modes then it's almost certainly a motor problem. Things to troubleshoot include the speed control potentiometer (if it's external to the motor): it may need just some cleaning and working it about a few times (you will need to re-calibrate the speed or mark the old position, though). If the pot is built-in the motor though...that's gonna require a motor substitution. Luckily this kind of motor was common, and you might able to get it new or cannibalize it from an old boombox.
Another thing to look for is the motor mounts: usually, the motor is held on the frame by using some rubber shock-absorbing "feet". If those wear/rot out, the motor starts wobbling about, causing all sorts of problems.
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it's almost certainly a motor problem
i came to this conclusion before posting on cpcwiki but having not a lot technical knowledges about tapes i prefered to ask experts!
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If the pot is built-in the motor though...that's gonna require a motor substitution
I think it is the case because after watching photos of tape motors on the net i had not been able to find such control on the motor drive of my cpc. I even removed the black plastic surrounding the motor (the photo of the previous post was taken before) with the asumption it was under.
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the motor is held on the frame by using some rubber shock-absorbing
I can't remember such thing but i'll take a look at this when i'll unskrew it.
I have another cpc464 with a good motor (at least the tape mech does not have this issue). I am ready to "cannibalise" it because it as other issues and is less usable than the Schneider.
But swapping motors is like a surgery for me because i'm not a soldering expert despite i have one soldering iron. In a previous post of this topic, @dlfrsilver (http://www.cpcwiki.eu/forum/index.php?action=profile;u=137) mentionned a capacitor problem. Does it worth investigate in this way before ?
About lubricants on the gears, this product is available in my local store. Does it fits ? :
SILICONE LUBRICANT, HIGH-PERFORMANCE LUBRICATION (http://www.3-in-one.co.uk/products/silicone-lubricant/)
Again thanks for your support!
If the potentiometer is not easily found on the CPC's motherboard, then it must be built-in the motor, and only accessible though a small round hole at the back, for which you must use a very small jeweller's/watchmaker's screwdriver (preferably a plastic non-conductive one). It's hard to tell from the pic which of those dark spots at the back is a hole and which just a welding point/rust/dirt spot :)
Some motors do indeed have a small cap shorted across their poles, but that's more for noise filtering purposes. In addition, the motor used in the pic has no such cap (at least externally). It would help to take a pic of where the leads that power the motor are soldered on the motherboard.
As for the oil, yes, it's suitable, but avoid spraying it directly on the gears or anywhere else: try getting a few drops on a q-tip, and apply it indirectly. I personally dislike spray-on lubricants, as they tend to also get oil where you don't want them to, but silicon-based oil seems to be only available in spray form >:(
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If the potentiometer is not easily found on the CPC's motherboard.
I didn't know it could be on the motherboard. I was aware of a possible screw to adjust the speed on some motors after searching about this subject on the net but i didn't know it was mandatory.
One thing i'm sure there is no such screw on the motor. The spots you see on the pic are holes but not screws. They seemed to be sort of thin paper layer protecting the inside of the motor.
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It would help to take a pic of where the leads that power the motor are soldered on the motherboard
i'll do that when i'll unskrew it.
Quote from: itneb on 19:49, 06 September 15One thing i'm sure there is no such screw on the motor. The spots you see on the pic are holes but not screws. They seemed to be sort of thin paper layer protecting the inside of the motor.
If the speed pot is on the motor, it will be inside the casing, protected by that paper-thin cover (usually rubber). But some motors have the holes without anything behind them. In any case, the service manual should reveal if the motor pot is on the motherboard or not. And yes, it's mandatory because speed control in a tape deck is necessary, not an option. Getting it "for the most part" right based just on the factory specs of the motor (which can be off by more than a few % between individual motors) is not enough, since most tape decks don't have a closed-loop speed control, but are simply set at the factory.
The motor speed is fine. If it wasn't the problem would be permanent. Don't start messing with the speed, because you'll need an oscilloscope to get it back to where it should be.
The deck just needs a decent service. Replace the belt, clean the capstans and cogs with a dry toothbrush (I use the wifes :D ). Then slap some grease (vaseline works great) on the cogs teeth and between all moving parts, including the metal parts from the buttons (just don't get any on the capstans). There's also a few open microswitches, you should spray some contact cleaner on these. Don't try to clean them with any physical contact method, you'll bend them out of shape. Then clean/roughen the rubber pinch wheels with fine sand paper. Clean the heads with alcohol using a cotton bud (Coton-tige). That should get the deck back to normal.
Bryce.
Quote from: Bryce on 22:04, 07 September 15
The motor speed is fine
Such a random variation of speed which affects all mechanical functions in all modes, is not exactly what I'd call "fine" ???
Unless you mean it's "within normal parameters" ;)
Quote from: Velktron on 10:51, 08 September 15
Such a random variation of speed which affects all mechanical functions in all modes, is not exactly what I'd call "fine" ???
Unless you mean it's "within normal parameters" ;)
No of course it's not fine, but it starts at the correct speed and motor speed calibration won't stop variance. It would only change the start speed before the problem occurs. Same with a drive. If the calibration is correct and it varies, then it was something else causing the variance, not the calibration.
Bryce.
I'll go tomorrow to the store to buy the weapons (grease vaseline, contact cleaner , silicone lubricant etc. you mentionned) and will try to give it a decent service.
I've taken some photos
rear with pcb mounted:
[attach=2]
rear pcb unmounted:
[attach=3]
more to come...
Front view of the pcb:
[attach=2]
I have problems posting more photos triggering security checks. Maybe should i wait a little..
Here is the rear of the motor:
[attach=2]
The motor reference:
[attach=2]
mech cogs:
[attach=3]
Finally the heads:
[attach=2]
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.
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).
[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.
ok you are right i had not seen it on the photo! ::)
i'll confirm it when i'll give it a service.
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.
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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 !
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.
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?
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 :o )
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.
Also, don't try it with a tape until the acetone has completely evaporated!! Otherwise you'l destroy tapes.
Bryce.
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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 (http://www.cpcwiki.eu/forum/index.php?action=profile;u=846) and @Bryce (http://www.cpcwiki.eu/forum/index.php?action=profile;u=225) for your help and sharing such knowledges it is very nice.
Finally i got it! ;D :
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!
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 :o ). 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.
Quote from: itneb on 09:07, 20 September 15
Finally i got it! ;D :
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.
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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 ?
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(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 ?
Quote from: itneb on 18:13, 21 September 15
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 (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.
It seems a bit complicated! Maybe i will look at it someday...But for now i will enjoy the one repaired!