Originally posted by: Marian Minhok Hi. I would like to post my experiences regarding typical problems with tape speed variations. I have fixed about 200 walkmans from Sony, Panasonic and Aiwa. However, I collect and repair only full-metal body autoreverse models made cca. after 1989. But most of my observations are valid for any model. Many people think that these problems are related mostly to wrong belt used, but my experiences are little different. So here is my knowledge listed in the lowest to the highest probability order. 1. Some mechanical deformations in cassette compartment. Mostly after walkman fell down to ground It is also very probable at cheap plastic models, where plastic door is self-deforming after 20-30 years. 2. Dry capstan bearings It will affect W&F a little, but it is not as audible as on cassette deck (as basic W&F of cassette deck is much lower). Lubrication is necessary every 20 years (even if walkman is not used). Use oil used to lubricate watches. I use oil with density "2" used to repair men's watches. 3. Dirty or dry moving parts of walkman Every dirty or dry moving part will result in increased resistance and therefore negatively affects W&F. If walkman is in good condition and it has no battery leakage traces, then it should not be a problem. 4. Dirty capstan, pinch rollers and head Well, nothing to say 5. Wrong motor Quite often this is the case. The gap between the rotor and the stator is very small, sometimes they scrub each other (some Sony models). Generally, the motor quality is very high (I think they're made to work forever), so it is enough to disassemble and re-lube them. 6. Dirty capstan or motor wheel after belt change Be very careful when replacing old belt with the new one. Especially if the old one is turned into goo. You have to clean the belt path very very carefully and check for any remains of the old belt. I use benzi-alcohol for this purpose. 7. Worn belt If the belt is too loose, then the walkman will not operate correctly (you will not be able to change the functions). When the belt rubber self-destruction process starts, it will take only short time (several weeks or months) until it melts, so it's quite unlikely that you experience problem with W&F because of worn belt. You will rather see it as "walkman not working at all". 8. Wrong belt size For many people, this is the most probable cause of W&F. Belt of the correct size is necessary for the lowest W&F, but even if you use different one, on non-DD models it is hardly audible. I tried experiment with 54x0.8 mm belt instead of 68x0.6 - and it works great on Panasonic and most Sony models! If you experience wrong behavior after the belt change, check also for another reasons, like dry motor bearing. Most walkmans use belts of 0.5 to 0.6 mm thickness. These belts are not made any more and are very hard to get. I had to order production for myself. If you need any, just PM me or contact another members. If you want to use thicker belt, it is possible, but not recommended. Just be careful - some capstan wheels have the groove width of 0.7 mm, so please, use 0.6 mm or 0.8 mm, but avoid using 0.7 mm belt (the gap width cannot be the same as the belt itself). Also, if you use thicker belt, the capstan bearings and motor will wear sooner. 9. Wrong belt quality Check for the belt width uniformity and other defects. They're quite often the cause of problems 10. Wrong pinch roller Not only belt rubber destroys itself after 15-20 years, but the same chemical process starts at pinch roller as well. The rubber either hardens or softens. Both have negative effect to the W&F and usually it is very audible. Some earlier Sony models use pinch roller that is only very little wider than the tape itself, so the pinch roller is not able to hold tape on capstan. As the rubber hardens or soften, the resistance between pinch roller and capstan decreases. If you listen to tape and W&F is audible more with some tapes and less with another, then it is very probably the pinch roller problem. Also, if it is more audible on one cassette side than on the another one, or, it is more audible at the end of the tape than at the beginning, it is very probable pinch roller issue (not necessarily true for models with two separate belts for each capstan, like later Panasonic RQ-SX series) 11. The winner is - polished capstan Yes, if the walkman is used quite often, the capstan surface is not rough enough (it is roughened at production) and it is not able to hold tape on pinch roller. The symptoms are the same as in the previous case. The help is quite easy. Dip the contact part to the saturated solution of FeCl3 (you can buy it at any shop with electronic components) for about 5 seconds, wash it and the surface is roughened again. Dip only the tape-to-capstan contact part. Never dip the part that is in contact with capstan bearing. If you have any other experiences, please let us know Marian EDIT: I get lot of questions regarding suitable oil. Do not use sewing machine oil, as it dries quickly. Use quality watch oil, like the one listed on eBay ID: 220964943928. It costs 2 Dollars only including shipping
@mihokm I have just found this thread whilst looking for another thread I had polished capstan syndrome on my DD3, if I pressed down hard on my pinch roller the device worked fine. I realised as soon as I swapped capstans from a donor machine Marian is an amazing person, the savour of the walkman IMO.
Forgive me if I', wrong; but I think it is impossible to sort out the capstans in a WM-EX1(HG) or similar machines because the capstan is enclosed within a brass capstan tube type object. Unless, of course, you completely strip the machine down to parts.
I want to share my experience regarding the problem of wow&flutter. The causes listed in the first post are all possible, but some are more likely than others. 1. When I repair a walkman, the basic cleaning and maintenance is done first: cleaning of pulleys' grooves, lubrication of capstan bearings, motor and other rotating parts. If these are done first, they can be eliminated as potential problems rights from the beginning. However it is to be noted wear on capstan and motor bearings will influence the W&F singificantly and simply re-lubricating those bearing won't eliminate the wear. Another thing that commonly gets ignored is cleaning of the tape path before a unit is used or after the service has been performed. Most tape machines I've seen haven't been maintained in terms of cleaning the tape path, which should be done about every 10-15hours of use. A lot of the points can be eliminated just by doing the above mentioned. 2. Wrong pinch roller: this depends on the type of mechanism. Many mechanisms will work with slightly different pinch roller, while others needs very exact dimensions to work correctly. For example, most mechanisms that use the big 13 x 8 x 2mm roller are not very sensitive to roller dimensions, exception being dual capstan decks. But, the smaller the roller gets and the less clearance there is between roller and capstan in stop mode, the more critical its dimensions are going to be. On those units where roller dimensions are critical, it's prefferable to keep the original ones whenever possible, as many new ones have eccentricity. 3 .In regard to belts, this again depends on the mechanism, some being way more sensitive to the correct belt than others. Thickness and elasticity are more important than the inner diameter. Some mechanisms have tight springs which are driven by camgears, case in which a very elastic belt will not work best. Generally, my recommendation is to use the same thickness belt as original. Also, avoid the cheap Chinese belts sold in packs of 50pcs for a couple of USD, they're just very non-uniform and can't be used in anything that drives capstans. Typically, the better a belt is the more expensive it will be. There will be walkmans and cassette players/recorders that are rare and you will not find a belt specifically made for them. In that case you need to measure the belt diameter and order one of that diameter. You can do the measurement using a cheap belt: find one that fits and then measure it. The rule of thumb is the belt should not be so loose that it wobbles on the pulleys, but it also shouldn't be so tight that the pulleys begin to have resistance when rotating them by hand. Belts by dimension can be purchased from FixYourAudio, DeckTech and others. 4. Mechanical deformations in cassette compartment (Point 1): although possible, it's unlikely to be a problem in most cases. And when it is, the deformations will be visible or can be felt as the cassette does not sit right in the door/cassette compartment. 5. Wrong motor (Point 5) can be excluded in principle if the motor has not been changed. However, the motor should be lubricated if you really want to eliminate it as a potential cause. Just lubricating the motor can reduce the wow&flutter significantly in some cases. I recommend using watch oil and lubricate both bearings whenever possible. When the back bearing is not accesible, lubricate just the front bearing. The commutator and brushes can also be sprayed with contact cleaner for better operation if they are accesible without diassembling the motor. Try to avoid disassembling brushed motors unless it's absolutely necessary. A worn out motor can also be the cause of wow&flutter, so if lubricating it does not improve the situation significantly and all other causes have been eliminated, it is possible that the brushes and commutator are worn out: this would require the motor to be refurbished or replaced. MNF1600B and DD motor do sometimes have internal friction, this being also seen in increased current draw (look the service manual specs for this). Most DC brushed motor shouldn't have a current draw with no load higher than a couple of dozen mA. If you measure currents of 100mA or more in this scenario, there's something wrong with the motor. 6. Dirty or dry moving parts (Point 3): this is, in my experience, something that is often neglected and can have an impact on wow&flutter, although in the majority of cases this won't be the main factor affecting the W&F. 7. Polished capstan (Point 11) is something I would consider after eliminating all the other potential causes. Typically a polished capstan is visible by naked eye, but that's not always the case. Etching the capstan doesn't have any disadvantages, so there's no reason not to do it if you suspect capstan may be polished.
Want to add 3 more items on this list, which although not as common can be causes of increased W&F: 8. Too high takeup torque: this can cause the tape to slip between capstan and pinch roller, creating random jumps in tape speed as the tape slips. The typical cause of this is a clutch that is not slipping enough either because of a fault or improper adjustments (some clutches are adjustable). 9. Too high backtension: This can cause too much drag and will be esepcially problematic if there is a variation in backtension. When a cassette player is put in play, the supply reel should rotate with some minimal resistance, not touching any other gears in the mechanism while doing a full 360° rotation. 10. Inconsistent takeup torque or backtension: variation in the takeup torque can also create a W&F issue. Any debris in the clutch can create such problems, having very high W&F despite everything else seems right. These issues can manifest erraticaly, sometimes unit will seem fine, otherwise W&F will be very high. Also, W&F can become higher at the end of tapes in such situations, as the clutch is slipping more. So the stiffer the clutch is, the harder it will be to slip at the end.
