Monday, March 8, 2021

Repairing the king! Bringing a Sony D-Z555 back to life and giving it a new rechargeable battery

Like many others that grew up in the 80s/90s, you probably have fond memories of going to school listening to your Sony Walkman or later on their Discman. Among the many models of portables that Sony made over the years, a few top of the line models remain in the minds of collectors and audiophiles alike as the best sounding portables ever made. Walkmans like the WM-DD9, WM-DD100, WM-DC2 with the king in terms of sound being the (semi-portable) WM-DC6 - which reigns as one of the best portable cassette players ever made.

On the realm of digital music, Sony had their Discman series. This line has a few players that commonly make the top of the list of the best players ever made are the D-Z555 (also called D555), D10/D100, D35, D303 and D350. More often than not, the throne of the best Discman ever made goes to the D-Z555 for a combination of features, looks and sound quality.

Note that the best portable disc players were made in the early 90s and below, when it was considered a luxury item made for audiophiles. When the Discman became more main stream, some features were added such as ESP (Electronic Shock Protection) or later MP3 discs playback, but with these new "features" it came price cuts and the end of their high-end units.  

The Sony D-Z555 was released in 1989 and it features not one but two (!) backlit LCDs displays, one of the displays spotting a spectrum analyzer (how cool is that for a portable!?). Inside the unit, you will find two audiophile-grade PCM66P DACs and for the very first time on a portable and consumer device: 8 times oversampling and a DSP chip. The player also spot a digital optical output (which was a very new technology in 1990, especially on a portable unit!), a remote port (for an optional IR remote) and line out. 

The Sony D-Z555 (or D-555) and it's 2 backlit LCD displays in action
PS: testing it with a great game soundtrack from the time the D-Z555 was released (1990)!

I got this player for next to nothing on a thrift store near me (by far the best item I was ever able to find on a thrift shop!). I couldn't believe when I saw that it was not only in great shape (including the original Sony sticker!), but it also included the original leather case and power adaptor. 

As it was somehow expected, the unit wasn't working. When pressing the play button, the displays would light up, disc would spin (a good sign) but it would give an error and shut down. 

Upon some research, this problem is relatively common and occurs due to the lubricant on the CD mechanism being dried. 

It was time to open it up!

Beautiful unit - all metal casing

Back of the unit with the battery holder cap removed

You can spot the 2 DACs in the lower portion of the board

After sliding the board to the side, we can see the CD mechanism 

Unfortunately, I forgot to take pictures of the mechanism before I cleaned it. But I used isopropyl 99% and foam cotton swabs to clean up the threaded rail and gears. After cleaning and with the player still open, I was able to test it and I the CD was able to play it! However, I couldn't play all the CD tracks and the sound was muffled on the right side and volume overall was very low. This was "smelling" like a capacitor leak issue. 

Time to dig deeper. I found this very helpful post on the great portables forum ( - from the user Jorge

It was time to remove the centre gear and completely clear it from the old grease. 

Mechanism after I removed the locking metal plate pushing the gears up

I removed the battery holder bottom part to be able to access the locking spring that hold the gears in place

Centre gear and its locking washer soaking on Windex 

While the Windex was doing its wonders to remove the old grease from the gear, it was time to investigate the audio issue: looking for SMD caps!

Now, continuing the investigation for the bad sound issue. On the top of the main board, something smells fishy (literally). 

Two SMD capacitors found on one side 

One SMD cap found on the other side of the same board. Evidence of leakage electrolytes near the SMD caps. The electrolytic cap seems to be sealed.

Evidence of leakage on the right hand side

More evidence of leakage near the SMD caps

Removing the SMD caps using a hot air station
(I used metal shields to avoid melting the plastic pieces nearby)

The leaked electrolyte traces after the SMD caps were removed

After removing the old caps, I washed the board with some soap and distilled water. Then rinsed with 99% isopropyl alcohol and let it dry. Luckily, no damaged traces that I could see. After the board dried, I installed new Panasonic audio-grade replacement caps (all 3 caps had the same spec= 100uF - 6V).

New SMD caps installed near the headphone jack

New SMD cap installed near the remote port

After the new caps were installed, I cleaned up the gear and its locking washer with isopropyl alcohol, dried it up and re-installed it. After re-installing

Now, after putting it all back together, it is time to test it! 

And it is ALIVE! Playing all tracks now works and no more sound issues: as a matter of fact, IT SOUNDS REALLY GOOD!

Now, as you may probably have realized. This Discman model uses a Sony proprietary rechargeable battery model BP-2EX, and without a battery, this Discman is not really "portable". 

I need to find a working battery...

The original BP-2EX rechargeable battery

These BP-2EX batteries haven't been manufactured for at least a decade. And if you are lucky enough to have one, they are no longer holding any charge. These batteries were also lead-acid which is an older and less efficient technology when compared to lithium-ion (Li-On) ones. 

Upon researching for replacement rechargeable batteries I came across this post on about re-building the BP-2EX. I later found that someone also created a 3D designed battery adapter that holds two standard li-on 10440 3.7V batteries. 

The adapter uses 2x 3.7V 300mAh 10440 batteries in parallel, giving a total output of 600mAh. Even though 600mAh is not great, is not too far off from the original BP-2EX battery. 

So here is the battery rebuilt process:

The 3D printed adapter (printed in glorious purple filament) and the 2 10440 batteries

Using a wire to connect the negative poles of the batteries to the connecting pad

I used a copper sticky tape to keep the wires in place and serve as connectors

Our home-made BP-2EX battery!

Our DIY battery adapter installed on the D-Z555

(*) Caution! Even though it works, charging your DIY battery using the OEM Power Adaptor will cause the batteries to overheat due to higher current provided by the charging circuit. By doing so, you will be shortening the batteries life and potentially deform the battery adapter (which was printed in PLA) and/or player on the long run. It is recommended to charge the batteries externally using an appropriate Li-On charger such as this one:

I hope you enjoyed the post and happy high-quality CD listening... and now on the go again!


  1. I discovered my old Z555 by chance today. It looks very, very good, the battery is probably defective. Still, it should work. However, it shows no sign of life when you press play. Power supply correct with 9V, but no display, not even "Charging". Is there a simple solution?

  2. Hi! Thanks for stopping by. Is your DC power supply the original Sony that came with the Discman? If not, are you sure the polarity of your DC 9V power supply is correct (matches the Z555)? Your original battery is certainly dead by now, so I would remove it immediately and try just using the DC power for now. Next check is to open the unit up to see if the DC plug has a cracked solder on the plug connector. Even if you it comes to life, you will need to open the unit to clean up the hardened grease on the lens pickup track... Good luck and let me know how it goes!

  3. Lovely job. I too have the DZ-555 that needs the capacitors changed but don't have the expertise or equipment to do it. The left, right balance is fine just sounds low volume. Derek.

    1. Hi Derek! The low volume is a symptom of the leaking capacitors (caps). I'm not sure where you are located, but if you are able to find an electronics technician near you to clean and replace the SMD electrolytic caps - you should do it soon to avoid further damage to this rare unit (the electrolytes in the caps are unfortunately corrosive and conductive).

    2. Hi Ed. Sorry for late reply and for your advice. Am in Heathfield, East Sussex so have to try and find someone. As I have said the left/right balance is fine just the volume on the low side but listenable. Just like having the volume control turned down. Compared to my Sony D-350 the volume certainly sounds low. They are both 9mw per chanel. Regards, Derek.

  4. I just found my old unit which I bought back when they first came out. I remember it being expensive, but can't remember how much it was. I excitedly powered mine up but it just chirruped for 15 secs and turned off. Upon opening it up I could see that it was the infamous middle gear problem. I'm going to give it a clean and report back. Thanks for the great write-up.

    1. Thanks for your kind words. Let me know how your repair goes!

    2. Ed, I don't suppose you know where I could get a replacement 'middle gear'? Most of the sellers on eBay look like they've been 3D printed and I don't trust those. The laser sled is the KSS 167B, of which there is scant information on the interweb.

    3. I got a replacement gear from ebay:

      It worked pefectly.

    4. Awesome, Andy! Thanks for sharing the link to the replacement gear.

    5. Ugh... the Line Out works perfectly, but as you may suspect, the Phones Out signal is very weak/non-existent. Time to replace those SMMD caps. I see that some are recommending Nichicon 220 uF 16 V Low ESR replacements instead of the original spec ones. As a matter of interest, which Panasonic model caps did you use?

    6. I'm not 100% sure as I had them in stock, but I think these were the ones:

  5. Hello ED, god articel. I've got the sony discman d-z555 also and I believe that the unit suffers on the same sympton you describe. But I don't believe that I'm able to fixe it all by myself. I believe I should it sold by ebay. What is your meaning?

    1. You could try to find an Electronics repair shop near you to perform the repair for you. Or if you want really to sell, you still should be able to fetch a good amount (even if sold for parts/repair) on eBay (this this model is quite rare).