Hello folks, I just finished servicing my GX-670 that was stuck in the endless auto-reverse loop and lost its FF-REW abilities. I took it completely apart, re-greased, and oiled the capstans, cleaned pinch rollers, the works. All the functions look good now, the cam cycles properly. But... W/F is terrible and FF/REW barely activates on a 90 min tape. I replaced the belt sourced from "Fix Your Audio", but the belt feels too loose. When I cycle through FF/REW I see the motor spinning but the belt visibly slips and stretches. It is a bit too long. I need to find a new belt or perhaps try a few to see which length works best. It is a square belt 0.5 mm thick and about 101-103 mm in circumference. Could you please point me to the right vendor preferably in the US? Thank you! Alex
First potential solution is to measure the inner diameter of the belt (this is the typical measurement, not the circumference) and order the next smaller belt available. For example, under the 0.6mm thickness belts: https://fixyouraudio.com/product-category/spare-parts/belts/belts-size/belts-square/belts06/ if yours is, let's say, 64mm go for the 58mm instead. Note the belt for GX670 is 0.6mm thickness not 0.5mm. Another solution is to order the belt from DeckTech (ebay) instead, never had issues with these ones as far as dimension. Don't know any US vendor unfortunately. About wow&flutter, a WFGUI screenshot would be ideal so both the waveform and the actual reading are visible. There are quite a few issues that can cause a high wow&flutter on these units: pinch rollers, a bad clutch gear, a worn flywheel drive gear, a worn motor. It would also be useful to know if the wow&flutter is bad on both FWD and REV play or it's much higher on FWD.
Valentin, Thank you for your expert advice and insights. I examined all the gears for cracks or wear. Fortunately, everything seems to be in good working condition. I attached the image, that shows how it was before removing the old grease, etc. I cleaned all of the gears, reapplied grease, and oiled capstans. Pinch rollers also got some cleaning with a lighter fluid and later with 99% Isopropyl alcohol. They look good now. The symptoms of failed FF/REW on 90-minute tape are in these shorts. (for some reason this forum did not let me embed them). You can visibly see the belt's behavior, but I would be very interested in your thoughts. I did not take the WFGui screenshot, since I could hear it audibly. I will, if needed. https://youtube.com/shorts/Q2-QscUcXMw?si=zE94YiIY1X9n-a5w https://youtube.com/shorts/TjbFIJhJzro?si=gDWZmk1sd6erWDYn I ordered a new belt from DeckTech (eBay) - GX674 model, the same mech. Thank you, once again! Alex
The belt does look to be loose, so can only advice to replace it with either a smaller one or a DeckTech one. As for WFGUI screenshot, yes please do take a measurement and attach a screenshot. Apart from these, is everything rotating freely by hand ? I mean if you want to turn the driving flywheel by hand (with a cassette inserted) how easy it is to turn ?
Valentin, everything is rotating freely, with no sticky points. Naturally, without a cassette tape, it is practically feather-light. The cassette tape adds some weight to it, but nothing that I would consider excessive. I took extra care to grease up some potentially sticky areas. It appears that the looseness of the belt also creates no traction that transfers from the motor spindle to the flywheels. (?)( or so I think) Additionally, I re-measured the thickness of the belt and it appears to be very thin - 0.45mm. On some other youtube videos, it is visibly thicker.
Ok, this is a good sign. That's how it should be. About the thickness of the belt, to me it looks to be the typical FixYourAudio thickness. Can't comment about other YouTube videos, because I don't know what belt are they using. Anyway, the thickness is not your problem, but the fact the diameter is too big. So proceed to get yourself another belt, I think this belt aspect is pretty clear. And please provide a w&f measurement (for both FWD and REV play) with WFGUI, otherwise I can't give recommendations in that regard.
Valentin, Here is the abysmal W & F. The first image is FWD play - very bad, speed is slower and also 4% range; the other one is REV - 1% range, better, but still shaky. I have ordered the belt from DeckTech. Since the vendor is in the U.K. it might take a while to get here. I think that this is mainly the belt's issue, but what do you think? I am a bit concerned that there is such a BIG difference in performance. Even though, I hear that having a small difference is not uncommon. I never had great luck adjusting perfectly auto-reverse decks to match the playback speed. One of my other decks is a Pioneer dual well, and there's the same thing - speed is just slightly off on reverse playback. But of course, it has much much better W & F. I also wanted to ask your opinion on the tiny capstan washers that broke off during dismantling. I could not save all of them, unfortunately. I understand that they are important. Are they critical for proper functioning in your opinion? Is there any way to find them? they are so tiny that I had to use a magnifying glass to even see them. I appreciate any ideas. Once again, thank you! Alex
I don't think that is the case because we can see a HUGE difference in wow&flutter between FWD and REV. From experience, belts from FYA are uniform. If the belt was to be the problem, we would see the same 1% figure on both sides as it's the same belt driving both flywheels. The belt could cause such a wow&flutter only if it was to slip under PLAY as well. The REV figure is pretty close to what I would consider normal on a WM-EX with some wear on the motor (which most of them have). I asked if there's a difference because the FWD flywheel is the one driving the geartrain and there are situations where imperfections in the geartrain cause increased wow&flutter only in FWD, which is what we see here. Given this you need to double check the FWD side and everything related. There are essentially 3 things I would check: the gears themselves (under magnifying glass), the 3 washers and clean the capstan of any residual oil (if it hasn't been done already). A small difference in wow&flutter (like within 0.05%) is normal because the geartrain is directly coupled to the FWD flywheel so the FWD w&f is typically a bit higher. This is normal, it's like that by design. If you look at the 2 flywheels carefully you will notice the diameters are not exactly the same. This is to avoid resonances in the belt. What washers are you reffering to exactly ? There are 3 washers on this unit: - one between the flywheel and the bushing (this is white in color); - one between the upper part of the bushing and cut washer (this is paper-like brown colored); - a cut washer which keeps the capstan in place (these are of different colors); The cut washer can be found in this FixYourAudio kit: https://fixyouraudio.com/product/washer-set/ The other 2 however cannot be found unless you have a donor unit. And yes they are important, not having these will increase the wow&flutter.
Valentin, thank you for your feedback and ideas. I appreciate it! The two that are placed on the upper side of the bushing, the brown colored ones (I saved one), and both cut washers. As you suggested, I will dive back into the mechanism, examine it even in greater detail, and just go over everything once again. I did not set up the "test mode" previously, just did not think that I needed to. but I am afraid this is unavoidable now. Once again, much appreciate your guidance here. Alex
Valentin, I tinkered with it more: more cleaning pinch rollers, and capstans, re-lubed the flywheels. Things improved, but not perfect. I also hear a consistent clicking sound. What can this be? About the washers: I only lost one fiber washer that split in half, all the others are present and intact. This 1st image is W& F from REV. The second image is from FWD. As you see, speed has stabilized and W&F has improved in both directions, most significantly in FWD. Thank you in advance. This little thing is frustrating, albeit beautiful. Alex
I wonder - because you not have mentioned it - if you tried to resolve this with FYA? From my experience of dealing with Marian Mihok (the owner of FYA) I would expect that he would do a lot to help. Just a thought.
No, I did not, and I do not intend to. Marian has helped me a lot in the past with other very hard-to-find supplies that saved my 'precious' gear, so I am forever grateful. I am just trying to finally get this Sony Walkman working properly. Since I dug deeply into it, I have realized that other issues are contributing to poor performance, and the belt is just one of them. Valentin has been an enormous help.
There are 3 things that can cause a clicking sound in EX mechanisms. To narrow it down, you need to pay attention to the frequency of the click. If it's a low frequency click (like once every 2 seconds), there can be 2 things causing it: 1. A cracked clutch gear, common problem on these units. https://stereo2go.com/forums/threads/wm-ex-series-tac-tac-sound-repair.7108/ 2. A warped idler gear, the gear between the driving flywheel and clutch. A cracked clutch gear is the most likely culprit, but you need to check to know for sure. With the unit operating, look below the PCB and observe both the clutch and idler see if the edges of the gear move up and down during rotation. If so, which one ? If it's a high frequency click (many clicks/second) it's the flywheel driving gear that is worn. I'm afraid you will have to find a replacement for that washer, it doesn't have to be the exact same one, but of same thickness.
Thank you, Valentin. It is a high frequency tick, about 180 ticks/minute. So I will have to look for a donor unit, I suppose. Unless you know a remedy for this. I kept the player going for about 4 hours playing a short prerecorded tape back and force. The ticks are still there but much less audible. Also, to my surprise the FF and REW functions got much better. And I am definitely out of the endless auto reverse loop. I can probably make something similar to the damaged fiber washer. Do you have any suggestions to the matter of materials? Once again, many thanks for your help.
In regard to a potential donor, it doesn't have to be a GX unit, can be EX as well: EX670, EX674, EX677, EX678, etc. Essentially any model with plastic flywheels will work as a donor. Only thing you need to be careful when getting such a donor is to make sure there's no rust on the capstans, since you will be needing one. If you need a donor or not, that depends if you are ok with the FWD w&f or not, value which will improve once you add the missing washer. As for the washer, I've seen a thread before on the forum about someone making such a washer for a SONY WM-D3. The guy used punches to do it. Can't find the thread at first glance, so probably needs a bit more search. The material used was also mentioned.
Valentin, thank you once again. I checked on eBay and saw that the supply of potential donor units is scarce. So I will keep my eyes peeled but also might have to learn to live with it. As for the tiny washer, I saw a post earlier on Tapeheads - a guy used a 1/8" hole puncher and a heated needle to make washers. It's quite ingenious, and I will try to replicate it. I read your post about the cracked clutch gear in great detail https://stereo2go.com/forums/threads/wm-ex-series-tac-tac-sound-repair.7108/ It was super helpful because it gives you ideas about what to look for. After taking a closer look at the pictures I took when disassembling the WM, I found the crack. Well, that explains the sluggish FF/REW. The crack appears to be small, not all the way through. I am wondering if I can try to repair it first with JBWeld. If not, I will get a new gear. What is an effective method of removing the plastic gear from the metal part? Any particular glue to use? Please let me know. Any suggestions are super appreciated. Best, Alex
In regard to the gear, there are 2 options: either replace it with a new gear (there are a few different sellers) or use a donor unit. With donor it's a gamble as you can't know for sure if the gear in the donor will be good (but most of them are). Given you also have the high frequency tick, I imagine you might have 2 different issues: both the broken clutch and a worn flywheel driving gear. Seen EX units to have both issues in the past, not that uncommon. As far as a repair goes, I'd say a repair is not possible because the plastic has shrinked and the issue here is the higher distance between those 2 teeth, not the crack itself. For removing the old gear from the metal part, you first need to remove the magnetic part of the clutch in order to avoid damaging it. It simply pulls upwards, note there's a white nylon washer underneath. After that you need to simply pry the old gear out. Don't recommend heating the metal part as you risk damaging the center plastic hub for the magnetic disc.
Valentin, thank you for your advice. I ordered the new gear replacement and will keep you updated on the progress as the parts arrive. A side note: I remember back in the day, I just tossed the broken WMs away and bought a new one as the cost of repairs was twice the cost of buying a new one. There went my WM-30 and WX48. Now I wish I kept them...
Hello Euroflash, Yes we have all been there and I even found a good replacement part for my Sony walkman too a seller on Esty. Sincerely Richard
