Problem/question regarding my newely bought Sony D6C

I have a question regarding my newely acquired Walkman D6C. I recently bought Sony D6C on ebay for around 550$ and changed belts cleaned head and demagnetized it but the sound is not good at all There is no wow and flutter issue. The thing is that all recordings even factory recordings sound quite muffled with treble going up and down, even my cheapest FX303 sound much better then D6C. Also recordings from D6C sound the same on the same D6C but sound awful on my Pioneer double deck as well as on FX303. I have made recording using PC line in from both D6C and FX303 and D6C is not good at all. Any advice how or even can I fix this ? Or it should sound like this ? I am very dissapointed in so called "king of walkmans"

 

Sound like the tape is wandering around messing up the Azimut. You might need to replace the pinch roller and perhaps also adjust the Azimut afterwards. Do you have an Azimut test tape?

 

Yes I have a test tape. Checked azimuth with software nak100. It appears to be ok on 16khz track. I think Im doing mesurment correctly. How to find if pinch roller is the cause? And what if I use very thin sandpaper on pinch roller? Will this trick work? If rubber is not bad? BTW I already changed belts. I am waiting to special lube to lube rewind ff gear thingie because sometime tewind is stopping on certain tapes and I saw a video how to fix that.

 

Did you listen to my recordings? It could be pinch roller right? If it is a pinch roller how easy is it to change it? Or is it better to sandpaper it alittle?

 

A bad pinch roller might be hard with a glazed surface or deformed, or with small cracks. if it’s the original one it’s quite certainly bad by now.
Here you can find a good guide on how to replace it, don’t bother with sandpaper. You spent 500$ on the player you should spend 10 more on a pinch roller before resorting to sandpaper http://stereo2go.com/forums/threads/wm-d6c-pinch-roller-replacement-complete-tutorial.7412/

 

Clearly replace the roller, as it's readily available at https://fixyouraudio.com/product/sony-wm-d6c-pinch-roller/ and the price is peanuts compared to what you have paid on the walkman.
I would recommend to replace all rubber inside it, especially the capstan ring and 2 idlers as it's likely these are going to cause problems in the future, even if walkman seems to be perfectly functional now.

Will leave the link with complete rubber kit for reference: https://fixyouraudio.com/product/sony-wm-d6c-cassette-player-walkman-complete-rubber-set/

 

Thanks I will order these soon.
You know what I am thinking? I think my problem is as if dolby b is engaging and disingaging during playback some sort. Can it be contacts or something?
Can someone tell me how to clean ll contacts etc? I think my D6C is later one. Even when I tried to play Dolby B factory recorded George michael the muffling is oging in and out more noticebly. Oh fixing this one in my country is ompossible I am thinking Maybe I will sell it if no real cause of this sound problem is found
Tell me wht to record and what tests do you wamnt me to do I have FX303 as well as quite a good Pioneer hifi system to compare to. Maybe we could culprit the issue

 

I have a test tape with several different frequencies to test. as well as have NAK100 software with digical oscilograph etc. (yes I know that software is much worst then real osciloscope but still)

 

You say your D6C is a later one: is it the one with SMD PCB or the one with through hole PCB ?
The ones with through hole PCB (which are the vast majority of them) have 3 potted hybrid modules: 2 EQ modules and a muting module. These do tend to fail intermittenlty, especially on older devices.
If you have a through-hole PCB it is highly recommended to replace these modules with new ones even if they are apparently working.

For reference, new modules are available here:
EQ - https://www.ebay.com/itm/263537248339
muting - https://www.ebay.com/itm/263851487685

A failed EQ module can manifest symptoms similar to this.
On playback, such a symptom would only occur on 120μs EQ (the NORMAL position), as both chrome and metal share the same 70μs EQ setting.
On record, this switch also changes the bias level, so it would be a lot more obvious. Do note that one module is for recording, one for playback and they don't necessarily fail at the same time.

Don't remember if I already stated this on the other thread, but here is a link to a thread I wrote some time ago covering most typical problems: https://stereo2go.com/forums/threads/sony-wm-d6-d6c-buyers-guide.7801/
So please refer to this thread as well, as you have the common problems already listed there and those must be adressed anyway.

In regard to Dolby engaging and disengaging, the transitions (between muffled/normal) are too gentle to be caused by a bad switch.
Switches can be easily cleaned after you remove the fron metal plate (the one with "walkman" logo). You just need to spray Kontakt 60 inside and move them back and forth 10 times or so.

As for testing with a test tape, a test will reveal nothing, as the problem is most likely mechanical. The only test tape that is necessary is a Dolby level tape (200nWb/m ANSI) to calibrate the playback levels for correct Dolby decoding.
But that's something you should worry about AFTER fixing the current problem.There is a tutorial for calibration as well, available at link in my signature.
In regard to your Dolby-encoded cassette, yes playing such tapes will make azimuth problems much more apparent than non-Dolby tapes.

Start by checking one thing at a time in a logical order, guessing is not a good strategy when it comes to repair.
A bad roller will pull the tape either up or down intermittently during playback (changing the azimuth) and that's something you can see with the naked eye. A cassette with transparent shell is ideal for this.
If the tape stays perfectly straight and does not curl at all, the next suspect are those EQ modules (assuming you have the through hole PCB).

EDIT: As stated above, things like the pinch roller should be replaced anyway, even if it's not the cause of this problem for a proper long lasting restoration.

 

Understood about pinch roller as well as all rubber parts. I already changed belts, will ordr all others stated above.
I will post photos I have taken now while dissasembling walkman. I think one of the capacitors is not ok it is bulged and I think it should be flat? Any advice on changing caps aswell?

 

One question regarding azimuth. I just tryed to tune by ear and on dolby B tape results are quite good. So it is off azymuth the hole problem I hope? How can I properly tune azymuth? I do not have any hardware osciloscope only NAK100 app and test tape with several frequencies.

 

Ok, you have the SMD board so you can forget about the hybrid modules as you don't have them (they're built with discrete transistors directly on the board).
That 47μF capacitor is an indication the unit was powered with reversed polarity at some point. You are lucky your motor servo IC is still good.
It should be replaced along with C317 (220μF @25V), it's one of the blue ones left of the DC-DC converter can. Apart from these 2 there's no need to replace anything else.
Those 2 caps should be replaced anyway for good measure.

As for the problem being solved by adjusting the azimuth, only you can tell that. I don't see how the variation could be caused by a misalignment... Did the variation completely disappear ?

For adjusting the azimuth you need a 6.3kHz (can be higher like 8kHz) test tape, single track (recorded mono) and adjust for maximum output on both channels.
For fine adjustment you need an oscilloscope with XY mode to observe the Lisssajous pattern: the 2 channels need to be either IN PHASE, 45 degress or 90 degress (procedure is described in service manual).
I'm not familiar with the NAK100 software, don't know if that has an oscilloscope XY function. In principle you can adjust it 95% good just by ear alone (although it's not what I recommend), it's just not going to be 100% perfect.

What you can do is the following (by ear): adjust until you obtain the desired result. If you pay attention, you will notice there is a small window where rotation of the adjustment screw does not produce any audible change.
Once you establish the limits of that interval, you simply put the screw in the middle of it.
It is to be noted adjustment should be done AFTER replacing the roller, because if the roller is messing up the azimuth, it won't be correct with the new one.

At this point you should proceed with replacement of the rubber parts and the 2 capacitors first then adjust the azimuth. You should also download the service manual as many of the adjustments are described in there.

 

Thank you! Where can I get good quality caps any idea?
So I hsould replace that bulged one and other two I marked on photo, correct?

 

For reference I am attaching 2 pictures with the 2 capacitors that need to be replaced in case unit was powered with reversed polarity.
I also mention that when this happens, the CX20084 will usually fry (this is not the case here). It is highly recommended to use this unit only on NiMH batteries.

For more context regarding this, please read this thread: https://stereo2go.com/forums/thread...e-plugging-in-any-dc-adaptor.7840/#post-62826
This is for reference to both you and others reading this thread as there are quite a few D6Cs with this problem and the CX20084 is becoming quite unobtanium these days.

As for the capacitors, honestly don't know where you could buy them in your country.
The big THT one you can probably find at a local electronic components shop if you have such a shop in your country, while the SMD one you will likely need to order from one of the big distributors: Farnell, Mouser, DigiKey, TME.
In principle all of these large distributors should ship to your country, unless there are some restrictions in regard to electronic components exports to your country. You need to check this on their website.
Idea is if you can find them locally, buy them locally. Otherwise look at the big distributors: start with TME as it's from Europe and shipping should be the cheapest (although can't guarantee it).

 

Thank you so much for help. I really appreciate it.
So one of these blue ones should be changed if I read second schematics correctly?
What about original sony adapter that was shipped with walkman? Can I use that?
Here on photo

 

In theory you may be ok using the original one. In practice the original one will output a much higher voltage with no load.
And this is important because the servo IC is permanently connected to the supply voltage, even when unit is in stop.

Note that what you have in picture is not the original D6C adapter (which is a linear one), but a later model that has been modified to be used for the D6C.
This being a switching power supply (I can tell it's switching because of the universal AC input 100-240V) will have a pretty stable output voltage and won't increase when it's not loaded as a linear one does.
I would prefer NOT to recommend using this, because others reading this may mis-interpret my statement, use a shitty swiching adapter and destroy their D6C.
So please read the thread in reagard to this problem carefully and decide for yourself.

In regard to caps, from the big ones only C317 needs to be replaced (the bottom one if you put the unit with volume slider facing down), as that's connected in parallel with the input voltage so that is the one that
has potentially been exposed to reversed polarity. You can of course replace both of them as they are identical.

 

Thank You for such informative and complete knowledge and help!

 

So I ordered pinch roller and whole rubber kit for D6C and searching for capacitors to order them aswell.
One more question on pressing play there is quite noticable background noise which is lower while engaging dolby B and practically gone while engaging C. What is the couse of this? Maybe headphone amp caps or something? Any ideas? Uploading recording of this noise (no tape played just pressed play wihtout a cassette): nodolby, then dolby b, dolby c, nodolby. notice how this noise changes.

 

It is perfectly normal for the noise floor to change, as the Dolby NR will also lower the noise of the amplifiers.

The amplifiers themselves have noise, the tape will only add to that noise.
Dolby NR will lower the total noise, not just the noise of the tape, as this would not even be possible.

 

Is this whiny noise normal for d6c? Can it be improved by changing some components on amp side? my cheapest ealkman doesnot have this tupe of whininglike noise just hiss