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. Typically, when I repair a walkman, what I initally do is clean the pulley grooves and lubricate the capstan bearing. Before playing any tape, I also clean the head, pinch roller and capstan thoroughly to avoid contaminating the tape itself. Most of the times I find pinch rollers and capstans that were never cleaned before, so this is a very important step. Sometimes, the pinch roller is compromised and needs replcement. If, after a thorough cleaning (that may mean using up to 5 cotton swabs) there are still marks or glaze on the roller, just replace it. Dry capstan bearings, dirty capstan, pinch roller and head and dirty pulleys (points 2, 4 and 6) can be eliminated from the start as potential causes if you follow this procedure. Wrong pinch roller (point 10) can also be eliminated when you replace the pinch roller. How the unit was stored plays an important role: storing it in a cool, dark and dry place will maintain the rubber much better than one kept in sunlight. Worn belt, wrong belt size and wrong belt quality (Points 7, 8 and 9) can also be all excluded as potential causes if the belt is replaced with a new good quality one from Marian Mihokm. It is to be mentioned though that not all belts found online are good quality. There are 2 important aspects to a belt from what I have found: its thickness and elasticity (for example the WM-EX series puts the belt under higher tension when FF/REW and hence the belt needs to be elastic) and the most important thing by far is that the belt is evenly cut across its circumference. So chinese belt packs should be avoided at all costs: they could only be used as secondary belts (form the capstan to the table reel drive) when no other options are available. The material from which they are made is also something that is not going to last, so keep that in mind. 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 chinese 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. 0.5-0.9mm belts can be purchased from Marian: https://www.fixyouraudio.com/ 1mm and 1.2mm belts are available from Deck Tech on ebay: https://www.ebay.com/itm/DeckTech-1...nner-Diameter-Rubber-Motor-Drive/324233009181 https://www.ebay.com/itm/DeckTech-1...nner-Diameter-Rubber-Motor-Drive/324421855142 I have used belts from DarkTech before and can say they are good quality, but some of them are old. There are of course other sellers that have good belts, but these are the only 2 sellers from which I have bought from, except for some sourced locally. 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 tape does not sit right in the door/cassette compartment. 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. I have found that just lubricating the motor can reduce the wow&flutter. I recommend using watch oil and lubricate both bearings. 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 the motor if it's not necessary. NOTE: A worn out motor can also be the cause of wow&flutter, so if lubricating it does not improve the situation and all other causes have been eliminated, it it likely that the brushes and commutator are worn out: this would require the motor to be 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). Dirty or dry moving parts (Point 3): this is, in my experience, something that is often neglected and can have a significant impact on wow&flutter. Any additional load in the mechanism will increase the wow&flutter. Keep in mind that even units that have a servo feedback circuit on the motor or on the flywheel are affected. There is only so much that the servo can compensate for. The servo is also unable to correct fast changes in load, because of the limited bandwidth of the system. It is recommended that all rotating parts be disassembled from their spindles, cleaned of old grease and relubricated with watch oil. The table reels also need lubrication: if they can be disassembled easily by removing a cut washer or C clip, remove them and relubricate. On many SONY models, however, it is not necesarry to disassemble for lubrication. NOTE: I have found that in SONY TPS-L2 type mechanisms (including the WM-D6C) old grease increases the backtension significantly. Just relubricating the backtension mechanism can decrease the wow&flutter by 0.02-0.04% WRMS. Increased backtension will also wear the head faster. Polished capstan (Point 11) is something I would consider after eliminating all the other potential causes. Note that the capstan can be a problem even if there is no visible polish where the tape rides. It's something that can be done just to be eliminated as a potential culprit, if there's no other suspect. It does not hurt roughening the capstan.
