Hello everyone!

I've decided to share with you guys what Dottor Walkman has decided to share with me. I hope I can interpret his descriptions well enough. I think it would be selfish to keep it to myself especially since I think there is much to be learned and one can never know enough and I certainly believe there is much to be learned from this.

Of course, everyone knows the Sony WM-DD series of cassette players. Wonderful players no doubt about it. Over the years, they have proven themselves to be as reliable as it gets which is even more true and relevant in the world of today, where quality has gone downhill no matter where you look. All of this would be great if there wasn't for one fatal flaw and it is, of course, the failure of the center mechanical gear. The reasons for this phenomena lie in the aging process of the plastic mold, or better said, material fatigue. Cyclic repeated load on the material as well as changes of the amterial properties, the most important one being tensile/compression strength, that happens over time cause breakage of the plastic gear rim. This can also be endorsed by temperature influences, especially lower temperatures, that make the material stiffer and unable to extend to accomodate the far more rigid and temperature-stable inner metal part.Anyway, I won't be discussing material resistance theory here but rather talk about the ways to resolve this serious problem.

So, let's begin! On the first picture you can see a standard center gear of the Sony WM-DD series player, in this case a WM-DC2, that has cracked. The crack is obvious and is approximately 2-3mm in length. The situation looks rather desperate, don't you think so?

The second picture shows two broken gears as the subject of this procedure. As you can see, the picture also shows all the tools necessary to perform this complex task.

Voila! The gear has been successfully put together. This can easily be understated as an easy task. To perform this procedure and to perform it accurately, you need the special tools and the knowledge to use them. Treating the very soft plastic mold is nothing like wood, alumium or steel work and you need good craftsmanship to carry this out. Dottor Walkman does not use any kind of epoxy molds to insert into the cracked rim but a composite plastic mass. The composite is a two-component material based on cyanide-acrylic mixture that has appropriate mechanical properties such as strength and chemical properties such as cohesiveness. This makes the procedure much more complex but the end result makes it worthwhile. This also means the differences from gear to gear are a lot more consistent.

Now that we have repaired the gear and made sure it's condition is no less than excellent, it looks like this one.

If you thought this is everything, you thought wrong. Since everyone here is an enthusiast (in some cases this is really an understatement), we don't do the things we do just for the function, we do it for the soul. That's why the gear has to be painted. Black paint that is fade-proof and resistant to mechanical loads such as the ones that happen in a gear transmission system is used and it is looking beautiful.

In the end, the gears are not complete untill they are returned to their owners, in this case, two DC2 cassette players. This picture shows a disassembled DC2 with unpainted gear installed...

... and this one shows the other DC2 beauty with a painted gear installed.

I think this is very impressive work to say the least. Enthusiasm is always a good place to start but as we all know, it is not really enough and it takes a lot more to accomplish this. The level of experties Dottor walkman shows here and has shown on several occasions before and on other types of equipment really makes me change my perspective on things. As part of my profession I am bound to know mathematics and structural design but still, I could not carry this out. Not in a million years.

In addition, I would like to post a link to a video Dottor Walkman has made where he is showing the two DC2 machines in question. The one on the left has the unpainted gear installed and the one on the right has a painted gear installed. My talian is terrible but I was able to understand the most, I hope you will too.

http://www.youtube.com/watch?v=SHwG9jqFxSM

I hope everyone is doing well and as much as I would like to say thank you to Dottor walkman, I also have to thank Plop and Renzgi to their contribution to my peace of mind

. Cheers guys and cheers Dottor Walkman!

That nothing less of stunning, the best weld job I seen yet, that sure last for years to come. No more epoxy is going to be use after seeing this.

Precisely shaped missing teeth As a dentist I am fully satisfied Great Job! & TERRIFIC SHARE, thanks Tuna!

Thanks guys! Don't thank me, thank Dottor Walkman! 

@DocP: Dottor Walkman's tools look similar to yours and it really gives me the creeps. I can already hear the sound of "the drill"

fantastic work !  you walkman chaps are not short of top sources for mending your walkmans

Dr Walkman's work is impressive. He is truly passionate and creative of what he does. Only starting with that such stunning things can be understanded.

He lefts no small detail without control.

i would love to know,

what about the sound?

and compared to the revised dottor dd9?

Why don't you show us a macro photo of your fixed gear, I cannot make anything and there's part of the gear that's hidden.

I did show the whole gear on top photo before last photo before installing it and I also rotated the gear in the second photo when installed in the photo while in the transport because the gear is their. I just refill any surface gaps and sanding it again before installing it, you are not going to notice where the crack was that the whole point  As far as marco goes, don't have a dedicated marco lens, as using a DSLR, just marco mode and was as close I could get, so it I can focus. 

Next one I do I will hopefully by then have a marco lens, to do the picture and do a marco shot out of the walkman. But if you can't see the crack from where it was at, which was still pretrty close, then it doesn't matter, job is good enough and much better improvement then what I use to do with the epoxy and will hold up as can't break it aparts and yes I try. And most important no click as did get the spacing dead on. Took me over two days to fix that gear as I had to wait 24hrs for it to cure per directions, you can stress it duing the bonding process otherwise bonding stop, so not easy at all as it took a couple time to sill in the gap and sand to get it perfect .

Here are two examples of Dottor Walkman's amazing work on the DD center gear. 

The gears have been restored to a point of being equal to new. In fact, eliminating the tension stress along the rim will ensure longer service life than the original gear had. 

The composite material used is not commercially available, only the chemicals, and as far as I know, Dottor Walkman is the only one using it. The composite has excellent mechanical properties such as strength (it is an isotropic material so strength applies to both tension and compression) and chemical properties such as cohesiveness. In short, when hardened it will ensure long term reliability and stability with respect to mechanical and temperature load.As can be seen, the material is formed and finishd to marginal tolerances which is quite remarkable.

If someone is interested in restoring center gears for the DD series, I am sure Dottor Walkman would be happy to do it for you. 

Instead you sure say how it done, so others can benefit and repair their, let face it how many people can afford to actually sent their out? But of couse you want to keep it a secret, like a corporation would to maximized a profit. plus it look like he use reinforced plasticine clay, so it really no secret.

But found another way that makes the gear also like new, since it can never be better then new and plastic molecular composition so it actually bonds, unlike CA, crazy glue or epoxy which doesn't bond to Polyethylene nylon. Plus their more to this then just the stuff use to bond the plastic and fill the gap. As the other issue is how wide the gap and if the gear is not oval, those issues need to be resolve and sometimes requires spitting the gear to make a circle, so it doesn't hit the forward gear wall, also have to be dead on on the spacing, otherwise you put stress on the gear and get the click. Yes I do know this.

I never said anything bad about his work, He does do good work, but you keep pulling it more then he even does?

If you never said anything "bad" about his work, like you say, then there is no reason for this self-justification, is there? Furthermore, why don't you just say you want to know what the procedure involves instead of playing a pro-bono legal council. Let's not forget you are running a repair shop and advertising it on the forum. One other thing Mr. M.G., you are the last person on the planet to teach lessons, especially in sales ethics.

For one I don't know you? But if you have a problem with me  PM me, and never said anything bad, you clearly started this, I didn't, if anything I said he did stunning work when I saw this thread and believe he one of the best never said anything otherwise, so their was no reason for any of this. But like I said before if you have a issue with me, feel free to PM me.     

Selective memory is a curious thing. Well then my son, let me refresh your memory. Have a look at this:

index.php?board_oid=193392314111653483&content_oid=201273818907358797

I don't know you, or whoever that guy is, so don't know what your problem is, but quite obviously that you do have a issue with me? So don't know what point you are trying to prove? But contact via PM already instead of being just a huge prick to me, otherwise going to do the same, because obviously you have me confused for someone else, that did wrong by you?

You know very well who DrMR2000 is. He is you. Let's not play games here. If you had any wish to resolve the matter, you would have resolved it two years ago rather than disappearing into the sea and then resurrecting from the dead with a new name. Why don't you send me a message. All of the contents will be strictly public domain I assure you.

No he not, but go ahead and believe what you want, you are obviously hard headed and no point of even talking to you.

Would you like me to post your real name and address right here so that others that might have already sent something to you can do a little comparison? 

I did sent you the PM, please read.

Retrodos, I don't know you (apart that you bought me a red DD unit some months ago) and never knew DrMr2000. Apart from that, I've seen something that called my attention:

I'm curious to know why do you have in your store for sell a broken DD9 here, and your description is very strange, as you simply say this:

"May have been drop or something, don't see any dents, but when you put a battery into it, the two light flash and you can hear it try to start but jams and door seem loose as hinge is broken !!"

It seems that you write it like if you were not a walkman technician. I can understand that a normal people can put this description, as they don't have skills for repairing, but I cannot undertstand why someone like you can do it.

As a skilled technician, I expect that you can repair it, right? And if not, you can post a photo of what's inside an explain the problem of that unit, that maybe you can't fix for a mayor problem. You are constantly posting photos dissasembled units; why don't you add one here?

Double-faced, multi-aliases, persons really suck.

Other people should know their aliases.

It would be fair.

Let not go their....Especailly regrading the transaction with the red DD you sold me with the keyword of the day being, "oil". I regarded you as a respected member and still do, so I didn't really push the issue. As far as the dd9 goes, it's exactly as described I bought them from another member with a few other walkmans in a lot, which had a couple of DD9's in the lot. I kept one and sold the other as it has a "broken hinge" pretty sure I can fix the other issue, but don't have a hinge, so rather then let it sit for years in a box , threw it up on eBay for someone else to have a chance. Plus have another that I will do photos of, when I have time.  

I not even going to try to deny what happen to Tuna, which was very unfair, but their a whole another story and good reason I left, as I lost over 18k and had some stuff was stolen, as I left someone to do the eBay listings and shipping and manage the store to another person I once trusted, he took a few walkmans ones I purchase off eBay and was fixing, LCD tv's and laptops, as we were running a resell shop/repair business and gave him 18k to get a lot of TV's and laptops for the store and during the weekend he packup and took off, I wasn't their but for only a couple of days out of the week. Which was mine problem not "Tuna" and I acted very poorly regarding the matter and am sorry for that and mean it, as I didn't mean to harm him in anyway. But was just was very pissed at the time for losing a large sum of cash to the point of being sick and was more concern about that and didn't care anymore, so I made excuses and lefted and lost interest in the hobby for a while!! I will make right by Tuna as he deserve compensation, already sented PM yesterday, to resolve the matter. He help me alot defending like he stated and considered at one point to be a freind.

BTW

I never screw any other members and done quite a few of transactions over the years and those that were affect were reimbursed, but never did resolve the issue with "Tuna", which made it worst, as he defended me the most, as I promise I would. That I do very bad for, not doing a while ago when I sure have.

It's more than impressive !

bravo Dottor Walkman 

Thanks Metad, you're too kind to me.

Dear retrodos,

Regarding that DD unit you bought me, I have nothing to explain or to hide as you may know. I sold it as faulty / for parts, and I never dissasembled it, so it was impossible that I knew what was happenning inside.

If you do a search over here using my nickname, you will see that in many posts I said I always took my walkmans to specialized technicians to repair. Many of them I took to a specialized official AIWA technician here in my city and the most complicated have been performed by Dr Walkman.

I never fixed any of my units. No one, even a simple belt. I can even post the invoices of my repairs, as I have them all.

Regarding the DD9, curiosly, while I was reading this thread this morning, I received an email from eBay noticing your DD9, so I followed the link and saw it.

I understand that maybe you have not enough skills of tools to fix the hinge (I can perfectly understand that), but I was not referring to that, but to the electronics. I find very strange that you say:

"when you put a battery into it, the two light flash and you can hear it try to start but jams"

How can a walkman technician say something like this? Didn't you really open it to see what's happening inside?

I took your word for that, as you explain this when I confronted you about the issue, reason why I never pushed the issue, or left a negative feedback rating.

Regarding the dd9 it does work on one side with audio on both channels, just not the other side, was going to fix the issue, but notice the broken hinge, so stopped as I don't have a hinge for it and expensive to find another broken dd9 with a good hinge, as they go for almost the same price as a working dd9 and being it works on one side, didn't want to just part it out, as someone with a another dd9 with good hinge could fix it, or use parts from it rather then end up in my parts bin and don't get enough DD9's in for repairs to keep it for parts, have seen one or two maybe within two years and didn't need spare parts. I mostly get d6c's, or d3's. I listed it for what it does, with broken hinge to be clear. Gears are intact screws are all there, none missing, and no noticable damage to PCB that one can see.

If interested in it can take pictures of the inside and give you serial, lf you are looking for a specific batch. No parts was taken out of it.

Let's not inflame the situation beyond the facts here. Of Hugo I can say only this, he is a serious collector and enthusiast but above all, a very decent and generous person. Might as well say it now but he was willing to drop out of bidding for a PX505 just because he already had one and I didn't due to the unfortunate events. Needless to say, courtesy of DrMR.

Personal messages (to which I have not replied) put aside, I would like to know why the charade? Why call me names and claim I am confused and delusional and don't really know what I'm talking about when everything that I have said has a firm foundation? What purpose did that serve? It wasn't until I said I would post the real name and address until you admitted what is already known to be true.

In my thread about this unfortunate event I talked about facts, what actually happened and not ever did I say a single word that might be interpreted as a profanity and I made it clear that I did not wish you any harm and only the best of luck in life for we were no longer friends and well, that is how it sometimes goes in life. Why did you do this to me? Do you know how that made me feel?

Let's not kid ourselves. We are all (at least a majority anyway) over eighteen here and we all have our profession and our jobs and some of you even their own business. So the first rule of business is "a satisfied customer". From a professional point of view, I cannot say you are an accomplished businessman. What would happen if I told an investor I our server crashed and that all the design projects for his residential block are - gone? Do you think he would care about that or would he be more interested in sanctioning me as severely as he could? My point is, if you failed to do what was the right thing to do ethically, you should have done what was right professionally. Regardless of how you see yourself (or someone else sees himself), getting compensated for the work makes you de-facto a professional.

I don't hate you, I don't wish you any harm and with His will you'll have everything a person needs to have. But we can't be friends anymore. I have forgiven you yes but I don't trust you anymore. 

I have nothing else to say.

Just did want this to come out this way, nothing actually personal, but sure have sent a PM instead of acting like a child and trying to hide, that I do realize now.

I wish you will let me repair the mistake, they happen from time to time and sure have dealt with the situation much better at the time and I didn't and drop out instead and lost interest, which wasn't the right thing to do. Yes I do now know how it feel, as been thur the situation myseft a few occasional and reason I wish to repair the mistake. At the time let a third party handle alot of thing, due to lack of time and I suren't have and didn't treat it as a business at the time, as I just did repairs on walkmans here and their, never advertise it, did it for a few friends here and their and really didn't take the matter seriously and lost track as was more into helping the guy get his business running and in turn I would make some extra cash long term and failed. Now I grow the wiser over the years and handle any transaction as if it was a business. As far as trust I don't expect you to, as that something you build on. 

that was my dd9...i sent a pair with some other walkmans to retrodos...(dmr2000)

just need to clarifuy this...

Yes it was one of the one from the lot I bought from you, was able to fix one, the other figure sell it as the broken hinge. But took down the listing due to it has bad mainboard, as like you said the service center did a number on it and would receive a big fat negative selling it like that. Won't have even bother to look inside closely, but "bub" was interested in it, look to see what the problem was and sure glad I did.

Pretty much a hack job will upload pictures when I get the chance to, but they screw up the flex cables to the servo, didn't notice it at first but then notice the excessive amount of flux so removed it and see that they melted the flex cable. Traces look ok after cleaning so board hopefully may still be good. But figure take "hurodal" advise and do the pictures instead, so people can see how one of these are made, then part it out.

At least the other one I was able to restore as they didn't get to far into that one, just needed belts and cleaning and replaced the variable resistor in the dolby block they broke off somehow, reason why only one channel only worked.