Hello all! Recently scored a WM-D6 for a decent price from japan. Has some interesting, albeit 'basic' issues. All functions (sans rec, which I havent tested yet) work intermittently, but there's a lot of distorition/muddy sound, and signs that c602 (motor creep) and CP602 (intermittent headphone amp failure) are on the way out. Plan on getting the replacement chips for cp602,301,302,303, and getting my friend with good soldering skills to replace them + repair c601. Will replace belts and check grease etc myself. Interesting problem. The left leaf spring battery terminal has corroded in half. still provides enough power to run, but its spotty. I've heard that the middle terminal is just for the old style rechargable pack. Could I hot swap them, or would that break things? Also, any other hot tips to evaluate or check while im in the unit would be good
You can use the middle terminal, as that is only needed for the recharghable battery as you mentioned. Not sure what you mean by hot swapping them ? Another tip would be to clean/re-oil the FF/REW lever, even if it's not a problem at the moment. See links in my signature.
Good to know, thank you! I just meant swapping them around--I wasn't sure if they were attached to a single block and had to be replaced as a complete set. If I recall correctly, it's silicone grease for gears and watch oil for shafts/metal mechanics? Also, re: links--callibration. I'm reasonably confident that I can adjust dolby and record level (trim pots and basic readings seem easy enough), but bias adjustment looks more involved and might require soldering? Is dolby adjustment something to take a unit from good>fantastic, or is it required to get the unit to good in the first place? (I'll figure it out if its the latter, but other wise i'll leave it be). Another question. I have a relatively scruffy looking d3 coming. I know i'll almost certainly have to replace the main gear and other mechanics, but does this model have problematic common electrical issues like the d6 and d6c I should be aware of? I haven't really seen anything in my research, but I *have* seen that you and deb are basically the experts of these devices so I thought I'd ask the man himself.
Grease I would only use for levers, everything else that's rotating on a shaft oil (even if it used grease from the factory). Oil is thinner and doesn't get gummed up in time, so even for slow moving parts (like that FF/REW lever) I think oil is better. Dolby levels really depends on how factory/previous adjustment was done. But usually on these devices it's worth checking as in most cases it will need some adjustment. If off by a lot, you will have audible imabalance. If that is the case the improvement will be significant, even on tapes without Dolby NR. If you use Dolby encoded tapes (especially Dolby C, which has way less tolerance) this can indeed make a good unit fantastic. However do keep in mind for correct Dolby decoding you need more than proper PB levels: - a properly recorded tape (bias, tape path, levels); - correct player tape path; - good frequency response (a worn/pitted head will affect this); Given how many variables there are, it's understandable why many think that Dolby is simply a technology that never worked or see it as a low-pass filter (it's way more complex than that). WM-D3 if it's clean wouldn't expect anything in particular. If batteries have leaked, there is a flex that tends to corrode underneath the battery plate which will render no sound. There are other things that can go bad, but none is seen so often to call it a common problem.
Hi and welcome to the forum. One comment I would like to add to Valentin's detailed reply is that the WM-D3 uses the CX20084 motor speed control chip which is also used almost all WM-D6Cs, as well as some other walkmans, including the WM-DC2 and WM-DD100 Boodo Khan. This chip is very easily damaged by the use of switch mode plug top power supplies (as virtually all plug top DC adaptors sold now are) and reverse polarity power supplies. I have come across a WM-D3 in which the CX20084 had been damaged by a switch mode power supply. Please see my post below for more information regarding these chips, which are now very difficult to find replacements for. Sony WM-D6C and DD Series Walkmans - WARNING! Read this before plugging in any DC adaptor!
@Deb64 Heard! I saw all of the issues that can occur with these chips when researching these fascinating bits of tech, so believe me I plan on 3d printing a shallow cap to place over the dc input forever more (if I can avoid depressing the little switch inside it, that is) I bought both units on Japanese yahoo via a proxy (good prices, but easy to get stung by shipping if you do something silly like buy a lot of 100 type 2 cassettes — ask me how I know that one lol). The amount of listings that verbatim said “checked it powered on with a random cable I had lying around, but didn’t test functions” made me want to cry. 5 seperate listings, all of which sold for a high price. I actually think I messaged you on eBay about the replacement chips for the D6 (in short, I was wondering if I could bundle an appropriate FET, NPN and appropriate caps to repair the 602 with the other chips, as I live in Nz (a bazillion miles from everything) and even over paying for the components I would save a LOT on shipping) for both of you: do you have any photos, directions, or diagrams on where to locate the c602, cp601,301-303 on the board? Both connections and the chips themselves on the other side. I had a look at the service manual, but some bits weren’t labelled and it was quite chaotic on the silkscreen diagram. im planning on reoiling and doing the belts when they arrive in the mail, so I wanted to take lots of documented photographs of the relevant potted chips to provide to my friend who has the soldering skills to repair the c602 for me. On that note, while doing that level of soldering repair, is there anything else that should be tacked on? Deb, I’ve seen in a few of your historic posts you mentioned something about replacing tauntlum caps (bad spelling, sorry), but I was unsure what it was for, or if it was on this module — does this fall under the ‘may as well if you’re already depotting and soldering’?
Minor update, I've bought a 4xAA battery enclosure with DC output, along with a female>male polarity inverter adaptor. Bit superfluous for most people, or for those with proper workshop style bench supplies, but for me it will let me test the unit without stressing out about the broken+corroded battery terminal. Plan on taping that adaptor in place and writing centre negative big bright and bold on the housing itself lol. I suppose for anyone who finds this via Google, this is an alternative power method if your unit is missing it's battery housing as those are much more expensive, or you have the same issue I do with a broken or missing terminal in the compartment itself. (just ffs make sure it's actually outputting <5.5v and is centre negative. No alkalines. Rechargeables like eneloop pros are the way to go.) Question for the pros. If alkalines are dangerous due to their ability to peak higher than 6v, why aren't more of these units fried and dead? My understanding was that alkalines were the main battery in common use during the heyday of these units, so I would have thought almost every unit would have been used with them at some point in its life. Unless older alkalines had a lower average voltage, so the peaks were still below 6v?
Can be either the maximum rating of Vcc isn't that high (we don't know since we don't have a datasheet) or that the tolerance on the spec itself is high (high manufacturing tolerances). Would incline towards the latter, as I've seen D6Cs myself that were used for many years with adaptors outputting 6.7V or more and not having any problem. However exactly because we don't know the spec or the tolerances, the best course of action is to NOT risk: either use only NiMH (simple solution) or install a 4V regulator. To summarize, fact some units worked just fine for years doesn't imply all of them are going to behave the same or that even those which worked will work like that forever. Given the scarcity of this IC (at this point it can only be found in donor units) and complexity of alternative solutions (like the ones based on BA6301) makes such repair non desirable. Besides, not treating this as a serious problem will feed your typical flipper narrative: that a burnt CX20084 isn't a big deal, it's an easy fix not worth dropping the price (as the walkman is "essentially" working). Seen this myself: a member buying a D6C and noticing motor was running all the time. Seller was insisting this is normal behavior and all of them do this... Funny fact is even after all the posts that have been made on this forum and on tapeheads, many of new buyers are unaware of the known problems (cracked DD center gears, CX20084, etc). There is a thread covering CP602 repair here: https://www.stereo2go.com/forums/th...fast-repair-of-cp602-servo-circuit-unit.1853/ The transistors can be found at any big electronics components distributor, they're nothing fancy. Not sure about which tantalum caps are you reffering, there aren't any in the potted modules.
