Hi, everyone! I'm not sure what is meant by "Tech Forums Below", so I will write a short description here - and then, if needed, I will move it to a Walkman's Chat section. So I've got this beautiful NM state DD9, however 99% of cassettes I play on it have RIGHT channel louder than LEFT channel. I tried different headphones and precision tuning the Dolby section inside the DD9, to no luck. Actually I am 90% sure the issue is not related with anything that lies after a head. Because when I just hit start with NO cassette, the white noise is pretty equal in both channels. So that's either head's problem (really? in both directions the left channel became less sensitive?) or something cassette/azimuth related. I would really really love to fix this. Please, advise! Just a short story: I took another cassette (supposed to be mono), played it FWD - hmmm, equal channels. Played RWD - right channel louder. Ok, that's something new (there is a difference now between FWD and RWD). I removed the cassette and switched it to the other side and put back in. FWD - equal channels. RWD - equal channels!!! What?? What's going on? I repeated this test many times with the same results every time. And that makes no sense to me except for some ideas of cassette tape being asymmetrically rotated around its longitude, or or or .... no other logical options. But that's just one cassette. Almost all others are pretty stable in having right channel louder than the left one.
Hello and welcome to the forum ! The problem you have is most likely related to a tape curling at the pinch roller problem. Due to some imperfections in the pinch roller itself or a misalignment of the roller bracket or capstan, the roller tends to pull the tape up or down, messing up the azimuth. So there are a couple of things to check: - visual alignment of the pinch rollers relative to the capstan. Is the roller parallel to the capstan or at an angle ? - is the capstan perfectly in the middle of cassette hole ? Any slight misalignment can tend to pull the tape up/down. - are the pinch rollers themselves in good condition ? If you haven't done so already, I recommend replacing the entire rubber set: https://fixyouraudio.com/product/sony-wm-dd9-complete-rubber-set-for-cassette-walkman/
@Valentin, thanks for your reply! Pinch rollers as well as the entire mechanism look mint. The Wakman was either perfectly contained, or severely refurbished prior to selling. Yes, capstan seems perfectly in the middle. Regarding the rollers alignment its really hard to say: in DD9 the head is springy, so when the cassette compartment is open, it "hangs" being way off the pinch rollers path.
How have you established that ? Have you removed the door ? It's impossible to say without removing the door first. However I advice to be careful of the flex cable, as it's a common point of potential failure. In fact the simplest test you can do is run a tape with door removed and observe if there is any tape curling at the pinch roller. This way you will know if the problem is mechanical or it's something else (head, head flex, preamp).
Yes, sir, I've removed the door. However it still wasn't clear for me whether the rollers and the head were aligned. I observed no visible curls. I am 99% sure it's not a preamp.
No, I don't think it's the preamp either, listed that just because it's part of the signal chain. You have to investigate the tape path more in depth, because since the problem manifests only in FWD play it's either a problem with the head itself (poor tape-head contact in that area) or the tape path is misaligned by the pinch roller/capstan. Also check the 2 plastic tape guides between the pinch roller and head: if they sit in the correct position, are properly fastened etc.
Hold on, hold on, the problem is BOTH in fwd and in rwd modes. In both modes channel Left is quieter than channel Right. That "short story" referred to a one unique strange case, when Cassette X located A side upwards - played Unbalanced in both directions, however that same Cassette X located B side upwards - played Unbalanced in rwd direction and Balanced in fwd direction. Unbalanced - right channel louder Balanced - channels equal
Ok, so let me know if I understood correctly: 1. there is one specific tape that plays bananced in FWD but ONLY when side B is upwards; 2. all other tapes have an imbalance with left channel being quieter; 3. the imbalance manifests equally in FWD and REV playback, with the exception of the specific tape mentioned at 1;
You are correct. Just a small note: there are some cassettes (like 1 in 15 or so) which would play correctly. However I am NOT sure how they are SUPPOSED to play. And unfortunately I don't have an access to any other professionally serviced deck (my DRM800 still waits for me to look into it) with a DEFINITELY CORRECT BALANCE. Could that be just a damn anti-luck? I mean I do know that left channels (as they are on the outer sides of the tape) tend to deteriorate more with time. However I didn't think such deterioration may be so prominent. Also my brand new Moby cassette also has the same imbalance. It all feels like a nonsense, right
Don't think the tapes are the problem given what you have stated, it just seems unlikely that 14 out of 15 are bad. About left channels deteriorating more with time, think it would take a lot of time for that to happen. And the first thing would be loosing the treble, before the actual level would drop. Remember watching VWestlife on YT playing a cassette 1000 times with no significant degradation. As stated initially, given the variability of the problem to me it looks like a tape path variability more than anything else. To me, your problem seems very similar to what is described in post #31 here: https://stereo2go.com/forums/threads/wm-d3-recording-balance-issue.9133/page-2#post-73513 Other hints such as that specific tape playing good but only when side B is upwards also indicate it's a tape path alignment problem. Could also be the fact cassette is not sitting pefectly in the cassette compartment, but at an angle so that's another thing to check.
@Valentin, I really appreciate all your help! Regarding playing a cassette 1000 times - that's one, but having mostly cassettes from late 60s to mid 70s - is a different one I've disassembled the door once again and there were no curls, no misalignments, no nothing. However I was able to notice one teeny tiny thing: maybe (just maybe) there is not enough back tension in my DD9? Do you know anything about how this can be increased? I don't feel like adding a greese is a nice option... Am I right assuming that the only back tension DD9 provides is via a slip sheet? I've also removed the pinch rollers and closely inspected them - they are mint. Definitely. Also I've added 2 tiny spongey pads to the door, so that it presses the cassette more firmly. Didn't help. Still investigating Thanks for bearing with me!
In this case the best thing to do is get yourself one tape that you know for sure to be good and try that given how old are these tapes. About backtension, this is achieved by the springs under the table reels and also by a backtension gear which has a spring so it's harder to turn. The service manual specifies a backtension of 1 to 3.5 g x cm. That would feel pretty light when turning by hand. Note backtension is not critical on compact cassette machines.
I'll think about where I can get a "definitely good tape" (I don't have any acquaintances with tapes ). Regarding the "backtension" - when I try to turn the reels/knobs/pulleys/whatever they are called by hand - I don't feel any difference between rotation directions. Both when the motor is working and when it is not working. P.S. Interesting observation: in FWD mode, without a cassette the DD9 plays as long as the supply reel is rotating (in any direction, left or right doesn't matter). However, in RWD mode, without a cassette the DD9 plays no matter what. Is such difference an expected behaviour?
You shouldn't feel any difference as it's a basic spring setup, so the resistance will be the same in both directions. And yes that should be the case regardless if motor is on (unit in PLAY) or not. Yes, that is normal because the black/reflective pattern for reel rotation detection is just on the supply reel, not on both reels (see picture attached). This is the case with most auto-reverse walkmans, because it's not necessary to detect rotation of both reels to know tape is moving since the 2 reels are connected by the tape itself.
Well, I found... Something... Fwd capstan is movable. With my finger I can slightly move it in and out or sidewise - I am not sure, the amplitude is very small. I thought I can just tighten that capstan's three screws, but no sir! One of those can't be tightened - I can screw it forever... What can I do? (Rwd capstan is dead still)
What I don't understand is this: do you have play of the capstan inside the bushing or the bushing/FG coil assy is moving relative to the case ? Given you tried to tighten the 3 screws, my understanding is the entire assembly is moving relative to the case. Note these screws don't need to be very tight, but just tight enough so the assembly sits flush with the case.
The play I had was of the capstan (and obviously its golden disc/rotor with a rubber ring). Yesterday I was really tired of all this fiddling and just disassembled the device. Not an easiest task due to lots of differences between Service Manual and real life '89 DD9 I managed to find the reason for that play. The corresponding motor in a PLAY mode had a serious visual wobbling (the other motor didn't have it). That wobbling eventually cause thrust adjustment screw to unscrew a bit. I tried my best to reassemble the motors while keeping w&f at least under 0.12% wrms ( which was an extremely hard thing to do, again due to Service Manual being completely useless in terms of real life w&f adjustment - the methods outlined there simply didn't work), however after reassembling there is one thing that bothers me. And I am not sure if it was like that before my tinkering: When in play mode I shake the walkman, in some directions of shaking I can feel (with my hand) the motors wobbling as I shake. Feels as if there was some weight inside moving as I shake it. But only in some directions. In most directions just a regular motor hum. Is this ok? Or should the motors be dead still in every shaking direction? I've put in a 90min cassette which is kinda tough to play (some friction inside I suppose) and when DD9 is put in my pocket at specific angle, I can hear music skips/dropouts even as I walk in medium tempo! I thought DD9 can eat absolutely everything, so I am really worried about not correcting the motors correctly (pun intended).
Motor was woobling in what direction ? It was changing its angle relative to the rubber disc, meaning it didn't stay perfectly perpendicular to the flywheel ? What was the cause of this motor wobble ? Is that problematic motor free to turn by hand ? Maybe it requires some lubrication. The adjustments are just 2: flywheel thrust play and motor left/right position. Those are not hard to do at all and can be aligned visually/by feel, ignoring what the service manual is saying. The thrust play should be about 0.1mm or less, while the motor position needs to be so that when running it's perpendicular to the flywheel. If the motor or mechanism don't have any other problems, the visually perpendicular position will also correspond with the minimum wow&flutter. About shaking, motors spindles are hold against the rubber disc with a spring (which is pretty light), so it obviously won't stay there regardless of how hard you shake the walkman. However shaking it light (similar to walking with it in a pocket) shouldn't cause any wobbling of the motors. The fact you have skips when you walk with the walkman is not normal, assuming the tape is not very hard to turn. Do keep in mind that, in general, a walkman doesn't have as much torque as a deck, so a problematic tape may be normal to struggle in most walkmans, including the DD9. But given I don't know the exact details, since I haven't felt the tape myself, it's impossible to give a definitive answer.
@Valentin After days of tinkering I've finally noticed a thing that's off: in FWD mode the tape is getting a tiny curl. However I have no idea what can possibly cause this as the capstans seem straight and alright. I tried cross-exchanging the rollers, but the problem persisted on FWD and no problem on REV. Please, help me! Here is the video, where I click fwd/rev/fwd; pay attention to the right side of the head, a tiny curl slowly occurs there
From the video it's unclear if the curl is just at the head or also at the pinch roller. It would seem like it's just at the head, but don't want to draw a conclusion as there's a lot of reflection on the cassette shell. I see 2 main possibilities: - if the curl is just at the head: cassette shell doesn't sit straight in the cassette compartment, head doesn't sit straight or uneven wear on the head; - if the curl is at the pinch roller and can be caused by a polished capstan, a not straight capstan, a not straight pinch roller bracket (note there are 2 brackets on DD9) or a bent bracket holding pin; The fact you exchanged the pinch rollers and problem remained on same side can exclude them as potential culprit. So you need to take every single possibility and check thoroughly as even slight misalignments of the capstans, pinch roller brackets or the holding pins can cause such issues. In regard to the cassette compartment, also check the screws holding the metal plate: if someone replaced those with screws with larger head that can push the cassette upwards. The battery door is another point to be checked it closes all the way.
