I recently purchased a WM-FX77 which have very bad W&F issue. Seller claims he replaced the belt and pinch roller, and they sure do look "new": but looking back at may low W&F WM-EX631, the pinch roller looked very different: The pinch roller on my EX-631 have may "grooves" or "wrinkles" on its surface, which I guess contributes a lot to the grip. But from all the information I found online, the pinch roller from the FX-77 are the ones that I assume most people would say is "good" (It has a matte surface finish and no cracks). So my question is, apart from the W&F, which one of these two is actually good? (Or both?) I'm asking because I would like to first make sure if the pinch roller in the FX-77 is good or bad, so I can plan better what parts I should buy in order to fix. Thanks for any advice!
The FX77 uses a WM-700 series pinch roller, it's a dimension used in many SONY and quite a few other brand walkmans. This one is the roller: https://fixyouraudio.com/product/sony-wm-701c-pinch-roller-tire/ Issue is FixYourAudio only sells the rubber tire, so you need to still have the original hub to install this type of roller. In regard to the wrinkles show in the picture, that usually indicates the rubber is old but doesn't always have a significant impact on W&F figure. Have also seen new Chinese rollers that have similar wrinkles but almost microscopic compared to what is seen in this picture. The EX631 roller shown in picture should be replaced as preventive maintenance. Can't say anything about the other one, since there's only one picture. As for W&F on FX77, there are a couple of things I would look at: - is the W&F same on both sides ? If no (higher W&F on FWD), the flywheel drive gear may be damaged. - is there enough clearance between rollers and capstans in stop mode ? These units have very little clerance and there can be situations where tape drags on the capstan that's not engaged. - is the mechanism rotating freely ?
Really appreciate your insights for the FX77! 1. Yes the W&F is higher in forward. I was very puzzled about that and you just shed quite some light to it However, could you tell me which one is the flywheel drive gear? I'm really unfamiliar with all the gear's name for now 2. I'm not sure about the clearance as I don't know what exactly is the normal stop position for the tape head and roller assy, the assy can't stay still without the plate. Or is there some way to check it without the plate? 3. From what I can see, yes the gears are all moving freely. But can't tell if they are moving free enough :/ Just to add some info, I can see with my eyes that the belt is wobbling very so slightly when in operation. Should the belt be definitely not have any side to side movements, or some is tolerable?
1. See picture attached. The marked flywheel has a gear which drive the bigger black gear above. Higher W&F in FWD means either that gear (or another one) has messed up teeth or the geartrain has significant drag. 2. Stop position is when none of the rollers are engaged and the lever is on the middle position. See second picture attached. 3. Remove the belt and rotate the marked flywheel by hand. You should have some resistance, but very minimal. In regard to the belt, most belts will have some non-uniformity. Really depends how large the non-uniformities are. What belt is it ?
Thanks again for pointing things out. I did took out the capstan and lubricated the shaft a bit, but I did not take close look into the gear underneath it so I can't be sure if it's damaged or not right now. I'd have to to check when I'm back to the proper workspace. It tried removing the belt and feels like the flywheel is turning quite freely, but again without having a properly functioning one I won't be able to tell if my feelings are correct. The seller did not state where he sourced his belt, but I suppose it's not from any reputable sources.... probably aliexpress or something. In the mean time, I recorded a short video of my FX-77 gears operating. Not sure if this will help much for diagnosing the problem though, especially with the crappy resolution of my phone camera. Some other info: W&F mainly come from flutter, I'm using Hanspeter Roth's 3150hz tape and get almost 2% (FWD) and 1.5% (REV) of flutter, while wow is at around 0.3%. W&F is around 1% in FWD and 0.8% in REV
For now I can only suspect this gear that is driven by flywheel gear is the main culprit.... I don't know what the previous owner did to it but it looks super roughed up when observed closely. (Not cracked entirely though, the markings seems to be from sharp tools when previous owner try to remove the retainer.)
In regard to flywheel there should be some resistnace since this is driving a geartrain + there are 2 springs (table reel and directional clutch) which add some resistance. When rotating it back and forth (in both directions) you should note very little resistance before the directional clutch engages with reel gears and more resistance after. Also note if there are any uneven spots in a full rotation rotation. Looking at the video, I would replace that belt with a FixYourAudio one. The non-uniformity looks high and belt is too thick for this mechanism. Indeed that black gear can be an issue on these mechanisms. I suggest cleaning that gear and inspect the teeth. As far as W&F figures goes, 1% and 0.8% WRMS is huge. A WFUI screenshot or video to see whe waveform would be useful.
Here's the video recording of WFGUI: I'm really curious about what could be found in the waveform, please do kindly teach me more about it Were you a professional cassette player tech, by the way? You seem to be very knowledgeable about all the technical nitty-gritty. I've already ordered a belt from fixyouraudio, let's hope it will help! And about the black gear.... I've already cleaned it with IPA. All the "blobs" on it are solid, not stain or something. Granted I added teeny tiny bit of grease to the gear teeth, but it's not enough to spread out to the whole gear like this. So I really wonder what happened to it......
In the waveform we can see how the actual speed variations look like and the frequency of variations (if it's low, high, intermittent spikes). The NAK-T100 does an even better job than WFGUI showing an FFT of the waveform, where we can see the actual spectrum. Depending on the frequency of wobbliness, we can have a general direction. For example: - pinch rollers will create a low frequency variation (high diameter, they rotate slow); - capstans will create a higher frequency (low diameter, higher speed); - uneven gear teeth engagement will create a higher frequency variation; - a belt will create low frequency variations; - motor usually creates a high frequency flutter if the problem is related to worn/dry bushing(s) or brushes; This is pretty generic, but looking at the waveform can give us a general idea of what to look for. Another example is if we see a regular spike in the waveform, but it's ok in rest. In this case we can suspect a gear tooth that's damaged for example. The ideal thing would be able to feel something when rotating the mechanism by hand or see something (like you seen the belt non-uniformity). However what's wrong won't always be obvious, hence why knowing some common causes of W&F is very helpful. I suggest reading this thread if you haven't already: https://stereo2go.com/forums/threads/wow-and-flutter-my-know-how.19/ Seeing the WFGUI recording, I notice the W&F isn't as high as you stated, being around 0.5% WRMS. Figure which is bad in my opinion, but some people stated to be "normal" for this mechanism (which suggests a potential common problem). Only serviced one walkman with this mechanism (WM-RX77) on which I obtained a 0.25-0.3% WRMS figure. Can't point out to anything at the moment, more investigation is needed. Other members made statements about pinch rollers creating issues with FF/REW. Does your unit FF and REW fine ? Does it struggle near the end ? So apart from trying a different belt, another test would be to remove one pinch roller at a time and test the unit without it in place. In regard to the black gear, the "blobs" are most likely from the mold. Seen that before on this mech, as long as teeth are fine it's ok.
