so ive been gone here a while, anyone who saw my post from ages back might recall i was making 3d printed parts for this model basically why ive been gone and havent updated it, while going through the stuff i was making i figured, why even bother with doing that first if a lot of people (myself included) have aging wm-10 models with degrading audio. theyd wind up as shelf pieces eventually going on like this anyways so, ive been getting better tools for this, and i believe ive found one of the only viable replacements for the original 220uf capacitors this is where i am so far (yeah i know, unfinished work again yaaay), but i need to order a hot air station to finish currently it was only after removing the 2 original capacitors i realized i was going to need a hot air station to finish, but its promising so far. thought id just share my progress on it even though im not quite done yet (image of original capacitor placement) (image of one replacement cap installed with the board folded back) now im not a freakin genius when it comes to capacitors, though given every brand of electrolytic out there does not fit, and generally browsing around basically every other feasible replacement wouldnt fit either, this is basically what im left with testing (eqv tantalum with the lowest ESR i could find that would fit), though its a tight fit. Going to be ordering a hot air station sometime next week so i can resume this, will update this once i have them in and a new audio test done to reiterate on the "not a capacitor genius" part, i have 0 clue how well this is going to turn out, its just the only capacitor i could find out there that would fit and has the correct values. this is kind of just an experiment to see if it will work better than the original aging capacitors. so i figured it would atleast be worth a try to see how it turns out just an edit-update- ordered a little (way longer) later than i wanted to but its all on the way now its disassembled on my workstation still so shouldnt take very long to get done when it gets here and is all setup long story short, i need to setup my own bank account just an edit-update- ordered a little (way longer) later than i wanted to but its all on the way now, didnt realize its already been this long shouldnt take very long to get done when it gets here and is all setup
and apologies for how long its been without an update on anything. took a long ass while getting new tools and finding the right capacitor that might work in this model anyways, essentially this has been what i was working on since my old 3d printing post. i really underestimated how long it was going to take to get to this point so again, sorry about the long hiatus
alright, i did replace the caps that i had in the image, but after hearing the before and after, i think i might have gone for the wrong caps. or atleast they werent the problematic ones. maybe there is some difference, but my hearing isnt refined enough to tell anyways ill have to try the other ones at the top-area of the board next go around (3 total), just take all electrolytics outtah the equation i dont have a service manual for this model specifically, so i was just kinda guessing based on where they are located in other models, so uh, whoopsie daisy (speaking of if someone happens to have the manual on-hand, would be much appreciated if you wouldnt mind uploading it) ill upload the audio files i recorded anyways, but i guess ill have to get more caps and flux
A question: what was the initial problem you were trying to solve by replacing these capacitors ? Listening to your recording, I would say the walkman sounds fine to me. I cannot hear any obvious problem. If you want a better frequency response in the low end, you need to replace C103 and C203 with 47uF instead of the stock 10uF. The service manual is available on HiFiengine, don't know if it's a good idea to upload it here given this. It's better you download it yourself from their website.
the main problem (apparent to me anyways) is the left channel is pretty faint, should be able to tell the audio seems to be louder in the right channel thats why this one was shelved for the last 2-3 years because of the audio problems. it sounds better than it did from back when i shelved it, so it might not be as obvious now but its there it was my daily for around a year when i was 15, still remember how it sounded like when i used to use it, so atleast to me its pretty obvious how much its degraded since then i figured this one would be easiest to tell since it was by far in the worst shape out of all my others. but i guess it isnt immediately apparent (crank your audio up a bit, it should become more audible) included an audio test from a f10 in amazing shape that i fixed a while back (keep in mind this is an audio test right after fixing it, so i didnt tweak anything prior) should give a bit of an idea of the difference in audio quality anyways
oh also yes hifiengine has the f10 manual i believe, but the f10 ii manual isnt available anywhere (F30 is japan eqv), i did extensively look for it but couldnt find it online (i had it years ago but the file got corrupt and i couldnt find who sent me it) probably would have been easier for me to work on the model i had a manual for, but its audio is still fine so i figured id tackle the problem child first
Ok, listened on headphones and indeed there is a channel imbalance: the right channel is louder but not by a huge amount. This kind of imbalance is typical to models that have the Dolby levels adjustable, which is also the case with WM-10 and its variations. I found such imbalance on many walkmans, on some the imbalance being way worse than what you have here. The levels with a 200nWb/m ANSI tape (which is the only one I recommend) should be 42.2mV RMS at the indicated test points (no load). Adjusting these levels is what you need to get rid of your channel imbalance and also have proper Dolby B decoding. I do not have the manual of the WM-F10II, but the manual of WM-10 II/WM-30 is available and those should be mostly the same apart from the extra radio section.
oh no this isnt a dolby inbalance or anything here, first person to use it since it was last used probably around the late 80s early 90s(old belt gummed up the motor, suspect it was likely the original so untouched in a closet or somesuch for ~30 years) it sounded perfect back then, but the left channel degraded over time since i used it so much, it sounds better now than back when i shelved it originally but you can still hear the imbalance ps i have a wm-10 ii aswell that is mostly just a parts model, and no its electronics are entirely different. as i said all of these models are widely different although their model numbers arent too much you would think that wouldnt be the case, but its like every model they completely redesigned it, super strange
though the wm-10ii is probably the only model that is actually pretty unchanged from the original, it actually seems to use most of the same circuitry as the wm-10 but thats just assuming from pictures ive seen of it online, dont actually own a wm-10 myself but the boards look almost identical
I understand the situation with the balance degrading over time. In my opinion, things should be taken in order by playing a tape with a test tone and starting to measure the signal levels at different points in the signal path starting from the head preamp all the way to the headphone amp. This is the quickest way to know for sure what exactly is causing the imbalance. If you can, please upload a picture with the PCB (component side) of the WM-F10 or F10 II (or any other F model you have), would be curious to see it. Never worked on or have any of the F models from these series (WM-10, 20, 30). Looking at the WM-F20 service manual (it's the only F one that I have), the main components used in the audio path are the same as WM-20 (and WM-10 as well), despite the PCB layout is very different. So while the PCB is re-designed, the basic building blocks have pretty much remained the same from the model without radio. Also noticed in a buyer's guide from '84 posted recently on Walkman Archaeology thread this statment: "The SONY WM-F10 is a virtually identical model [to the WM-10] with the addition of a built-in FM funer".
ah yeah, "virtually identical" as in "sounds and functions about the same aside from now having a radio" i can upload some additional pictures of the f10ii later on when i dig back into it, and some from the f10 if i can dig up some of my old pictures. though essentially its just 1-2 220uf caps replaced with 47uf ones, placements are mixed up, some additional small electrical components here or there (smd chips, ic chips and whatnot) revamping their circuitry to accomplish the same task (but more effectively i guess?), maybe for better frequency response as you mentioned and might interest you, they also changed the radio layout aswell, internally and externally, an obvious physical change being the original f10 didnt have AM while the f10ii got AM. (f10ii you can see the switch/selector) thought that might be mildly interesting yet not immediately apparent cant say i know much on radios, so afraid i cant give a good technical analysis on that one lol. makes me wonder why it wasnt included with the original f10 though never looked much into the electrical layout changed much till now, though certainly pretty interesting. wish someone who was an engineer at sony back in the day could give some insight on the technical details like that in these older models
