Sony WM-DD9 – continuous clicking on power-up, FF & REW LEDs on, no key response

Hello everyone,

this is my first technical post here on Stereo2Go, so first of all: thank you for maintaining such a valuable knowledge base around vintage Walkmans. I have been reading many threads here while trying to understand how Sony DD Walkman work.

Regarding an issue with a Sony WM-DD9 I would now like to describe my case in detail and start a technical discussion, as I am trying to determine whether this unit is realistically repairable or whether it may be affected by the well-known DD9 cam gear problem.

Observed behaviour:

• Immediately after inserting the battery (no key pressed), the unit starts making a loud, repetitive clicking noise.
• Both reels alternately make small left-right movements, as if the logic is switching between FF and REW.
• Both LEDs (FF and REW) are continuously lit.
• The unit does not respond to any keys.
• The behaviour only stops when the battery is removed.

Checks already performed:

• The unit has been opened carefully.
• Both belts are present, intact and appear almost new.
• Given that the behaviour starts immediately at power-up, before any play command, I believe worn capstan rubbers can most likely be excluded in this case.
• End-position switches S702 and S703 were checked electrically:
  • both are open (no continuity), which seems correct as long as themechanism never reaches its reference end position.
  • the switches themselves are mechanically functional.

Not checked so far:

Correct position of the two P-Leaver with reference to S702 and S703 switches as I don’t know how to check. Advice is very much appreciated.

Interpretation so far:

From what I understand, the logic seems to be alive and actively trying to reach a valid mode reference, but never succeeds. The alternating reel movements and constant FF/REW LEDs suggest that the mechanism does not reach its end position, so the controller remains in a kind of endless initialization loop.

I am aware that many WM-DD9 units with similar symptoms are repairable and that in most cases belts, rubbers or re-indexing solve the problem. However, based on the checks above and the specific behaviour, I am concerned that this could be one of the cases where the transparent green cam gear is cracked or slipping under load.

As far as I understand from previous discussions here, this cam gear is specific to the DD9, not interchangeable with the common DD center gears, and unfortunately not available as a new replacement part.

What I am looking for:

• Confirmation or contradiction from experienced DD9 repairers: does this behaviour match your experience with a failing cam gear?
• Are there any diagnostic tricks (short of fully dismantling the mechanism) to further differentiate between a re-indexing issue and a cam-gear-related failure?
• In case the cam gear turns out to be the culprit: does anyone know of potential donor units or have experience sourcing a usable replacement?

I do not feel confident enough to dismantle the mechanism further myself, especially around the cam gear area, and I would like to make an informed decision before proceeding.

Thank you very much in advance for your time and for sharing your experience.

Best regards,
Timo

 

Mine do the same thing if I haven't touched them for a while. Like, if they've been sitting idle for a year. Most often, it's a combination of belt slippage, hardened lubricant, and cleaning the internal switches. If I rotate them more often, the problems don't occur. I don't know what your specific problem is, but I would start with new, tight belts.

 

@Timo The microcontroller needs to initialize (engage FWD, REV, STOP) before any input from the buttons will work.
What happens when battery is inserted is FWD motor runs, FWD solenoid is triggered, mech should engage in FWD. This means S702 is closed.
Then same thing happens with REV, it's briefly engaged so the microcontroller can "see" the S703 closing.

If this doesn't happen for mechanical reasons, it will go in a back and forth loop and both LEDs will be lit.
However do keep in mind (and this is true in general when it comes to diagnostic) that a particular symptom doesn't necessarily point out to a single fault.
In this case old lubricant, slipping belt(s), slipping capstan ring(s) and broken camgears would generate the same symptom.

Note the top camgear is visible without disassemblying anything, just tilt the main board (jack needs to be removed - 2 screws and battery + desoldered).
You can also engage the solenoids manually (one at a time) and rotate the middle pulleys. This way you can see if the mechanism can be fully engaged by hand or not.

My recommendation is to fully service the unit rather than adress a specific problem and do nothing else.
Because those camgears, even if they're good now will fail in the future if the mech is not cleaned and re-lubricated.

New camgears are available in China: https://www.goofish.com/item?spm=a2...c2rlEI6O&id=765846362700&categoryId=125958001
Wouldn't trust using a donor if this is the problem, as you really don't know if the gears are good while paying half of the value of a good DD9.

 

Glad to see that repro cam gear exists, Valentin! Hopefully, they'll become readily available someday, so I can stock up on a few!

I'm always a bit hesitant to use the DD9, to preserve the cam gear (and head). This is especially true after previous experiences with cam gears failing in Sony FH boomboxes, for example.

I completely agree that a complete overhaul is better than a makeshift solution. Especially if it's going to be used a lot.

 

Guys, thank you very much for the very detailed and well-explained reply, I really appreciate you taking the time to write this.

What concerns me most at the moment is how loud and aggressive the mechanical noise is during this fault condition. It sounds quite violent, that is why I first assumed a mechanical damage.

Your point about performing a full mechanical service rather than chasing a single symptom is absolutely valid and well taken. Before going any further, I plan to follow your suggestion and first do a visual inspection of the top cam gear without fully dismantling the mechanism, just to establish a clear baseline of its condition.

Due to being away from home, I will unfortunately only be able to continue working on the unit again around mid-January.

In the meantime, I wanted to ask: Is there any experience with the Chinese reproduction cam gears you mentioned so far? In particular regarding material quality, fit, and long-term reliability in the DD9 mechanism.

For reference, here is a short video showing the exact behaviour of my unit, including the loud clicking noise:
https://files.fm/u/zk38sat9yu

Thanks again for sharing your experience — it is very helpful for approaching this in a structured and careful way.

Best regards,
Timo

 

The mechanical noise is typical of this mechanism, those loud bangs are the solenoids engaging and that's the typical sound even when it works.
Can't point out to what the exact problem is based on this video, but it's likely a combination between slipping belts and old lubricant.

Regarding the mechanical restoration, if you are willing to wait a bit I am going to post a tutorial regarding that (have the pictures already), but not sure exactly when.
First thing's first, inspect the camgears visually an try to manually engage the mechanism in FWD and REV.
Don't forget to disengage as rollers will get a dent if mech remains engaged. And I recommend keeping the original rollers if they're in good condition.

About the Chinese camgear, can't tell anything about its long term reliability because I haven't used it yet.
However in my opinion it's the only option to be considered, not worth paying a small fortune on a donor in unknown condition.
Generally speaking it's pretty unlikely the camgears are broken, that's why they're not readily available as demand is not that high.

 

@Valentin I would love to see your tutorial about the mechanical restoration of the DD9
in the future. At the moment i still try to learn how to service and repair other direct drive mechanics to gain more knowledge and to improve skills before I feel comfortable and prepared for the DD9.

 

Hey guys,
I‘m back from vacation and started to inspect the DD9 once again.

Checked the top cam gear:


But have not discovered any damage comparing it to a new one:

The belts seamed also to be in a decent shape.

It seams that the housing, when it is mounted, is applying a force onto the red circled area to compress the electrical connection on the other side of the PCB. That has the effect that at least one of the three housing screws need to hold that clamping force. Is this the intended design?


It appears that the leaver (red circle) controlling the switch S701 could slip over the switch when the device is in a upside-down orientation as the leaver has some play. Also I made sure that the respektive P-leaver were positioned on the blue highlighted areas right under the switches S703 and S702:


I moved all functions (leaver and gears) mechanically and made shure there is no sticking behaviour. Aferwards I assembled Everything and did a function test with limited hope to be honest…

But to my surprice the initialisation process was compleded as intended and no lights were lit! Now the device seams to works perfectly on all functions. I‘m so happy, still can‘t beleave the sucess.

I know that a full service still is neccessary but I now know that at least the device is working.

Looking forward reading your thoughts on my observations and to the upcomming DD9 service tutorial

Best regards,
Timo

 

Yes that is the intended design.

Lever controlling S701 shouldn't slip when the PCB is fully pressed down. Make sure the tip of that switch is not bent.

Glad you got the DD9 working. Will update soon regarding the service tutorial.

 

It's great that it's working properly again. The casing provides the counterforce for the battery compartment spring. Therefore, it's recommended to reassemble the casing with the battery compartment open. This way, everything will be in place when you reassemble the Walkman.

It's now important to use the Walkman at least a few times a year to keep everything loose. Enjoy this beautiful Walkman

 

That makes perfect sense. Thanks for the explanation

 

Hi @Timo.
It seems that my unit have the exact same problem.
It was still working perfectly fine 6 months ago. It was sleeping till then in a drawer without battery in it.
Today, I tried to play some music and there was that clicking noise with light lit on the control panel.
I opened the unit and saw that the belts were fine to my eyes. I removed them and checked their condition as I could.
Now, one of the belts seems a bit loose. I ordered new ones and new 470µF 6.3v capacitors.
If replacing the belts solve my problem, great. If not, I will replace the capacitors hoping for good.

 

The 2 x 470uF capacitors are for mains hum filtering if an AC adapter is used. Not related to your problem at all.
Also, it's important to use low leakeage (electrolytic type) caps there as otherwise they will drain the battery.

As for belts, they need to be tight to work as there's singificant load from the camgears. Slightly loose will not work.

 

Thank you @Valentin for those informations.
I hope that the problem is only related to the belts.
I inspected the gears and I didn't see any problem.
I don't know how to remove the 2 flat pulleys in order to have a better look at the big green gear.

 

It is recommended to do a full service on these DD9s. A tutorial will come in that regard.

Pulleys are held by cut washers that are hidden underneath the cassette compartment plate.
There's a lot to be removed to get there and by that point it's worth doing a complete service rather than just inspect the gears.

 

That is some good background information here

 

Good luck with your repair mate. Please keep us updated here.

 

waiting patiently

 

I actually managed to get my hands on another DD9. On this unit, one belt was completely blocking the forward drive and the other belt was clearly stretched. It appears that the mechanism was stuck in forward play, and both pinch rollers show flat spots.

The overall cosmetic condition seems great; the only issue is that the battery cover shows several dents and does not close properly, as seen here:



The battery cover can be pushed all the way down, but it does not stay in place and opens to an intermediate position, remaining partly open.
It appears to me that someone tried to open the battery cover using brutal force in an attempt to open the cover without engaging the release mechanism.

How can I fix this issue without damaging anything else?

 

You need to check if the latch mechanism is still intact.
That battery compartment does come out completely if needed.

Btw, DD9 tutorial is here: https://stereo2go.com/forums/threads/wm-dd9-restoration-tutorial.11142/#post-91020