MHZS CD33F Modified Tube CD-player (recap/remod)

Recently I’ve bought myself a Chinese MHZS CD33F tube CD-player which was in working condition, except for the remote. The remote was already taken apart and the CD-player itself had already been modified by the previous owner. This modification was based on several articles found on the internet.

What he intended to do was the following (if I can recall it all):

  • Replaced the output electrolytic capacitors with 10uF ClarityCap film capacitors
  • Remove the opamp and bypassed it
  • Removed the electrolytic capacitors in the audio path between DAC and opamp/tubes.
  • Removed blue LEDs underneath the tubes
  • Changed a few resistors to compensate for the absense of the opamp

Despite his pretty low level of knowledge and skills he actually did manage to modify the CD-player and it was working! Unfortunately it was not the best attempt of modifying a CD-player, that I will show you further on this page.


I started to take a look at the remote. A heavy and very well build remote with a metal casing. Very well crafted and a nice finish from the outside. Although, the inside was not that great.

Bad quality and obviously lead free solder made it look very bad, but that is what happens when soldering with lead free solder. All solder joints will dry up dull, no shine what so ever.

The problem was the way the battery was held into place and made contact or not with the circuitry.

I choose to order a bunch of battery clips that can be soldered onto a PCB. Although there was very little space left, I managed to fit the holder in and also get the lid back on.

Installed the new battery holder and give the PCB a good clean. Also replaced the electrolytic capacitor which was pretty bad already.

The CD Player

Now that the remote was fixed, I had the chance to listen to the CD player for a longer time. Sounded pretty nice, but I suddenly heard static noise comming from the right speaker. It was there when the relay in the output stage switched on, so it had to come from the CD-player.

I decided to take the complete CD-player apart and redo the modifications, also replace all large electrolytic capacitors in the power rails. The capacitors in the audio path were already bypassed or replace with film capacitors.

The inside of the CD33F

Let’s take a closer look at the PCB’s and the modifications.

Top view of the mainboard

Power supply board

Power supply board – top view
Power supply board – side view

I replaced the large electrolytic capacitor in the power supply as a precaution. It got very hot because of the large power resistors next to it. I replaced it with a 105°C which last longer.

Modifications and other work

The standard 10uF electrolytic capacitors were replace by much larger “ClarityCap” type film capacitors. Not the nicest way of putting them in there if you’d ask me. Not to mention the burnmarks on the capacitors inflicted by a soldering iron. Luckily the capacitors measured perfectly fine on my LCR meter, so no need to ditch them and get something new.

More damage by the soldering iron

The output relay got a bit fried during the first modification attempts.

Soldering works

Although the end result was a working CD-player, the soldering could have some improvements. Another thing the previous owner and ‘modifier’ did, was to remove the blue LEDs that lid the tubes from underneath. That’s certainly something I would have done!

The improvement

First I removed everything from the board that shouldn’t be there, was badly soldered, defect or will be replaced by something else.

The relay

I found a used but good relay of exactly the same type, so that one could go in.

New electrolytic capacitors

New Panasonic FC electrolytics installed

New film capacitors and the old ones reinstalled

The ClarityCaps installed in vertical position
New 1uF film capacitors by Vishay/Roederstein MKC (Polycarbonate)

Fix the output wires

The output wires were non-isolated. I thought that this short piece of wire also deserved an upgrade.

Reassembly of the CD33F

The components removed/replaced in front of the renewed CD33F

This was a really fun thing to do. Working on an already great CD-Player and improve it further.

I don’t think this CD-player will leave my audio setup any time soon!

4 comments on “MHZS CD33F Modified Tube CD-player (recap/remod)

  1. Hi i have the same cd player but it has a Letter E after the 33, well my cd player arrived with a smashed cd transport, do you know what cd transport I could use in mine, Thanks Ben, Great work on your cd player, liked you said it was a good cd player.

    • Hi Ben,

      I’ve been looking what the differences are between the F and E type.
      Haven’t found a definitive answer that it could be the same Sony KSS213Q transport.

      If yours is damaged in transport you should still be able to determine the transport assembly used. That would at least tell you what laser assembly is used, but won’t tell you anything about the tray mechanism.


  2. Great Job , congrats , well documented with nice pctures… ! Thank you very much !

    I have a question : do you know where to get complete cd-Loader Mech , mine is damaged , need a new one and don’t know where to get !!

    Perhaps is there someone who has a working loader and wants to sell ? Is there a mechanism in another cd player that works ??

    Thanks alot , would be great to get help !! Uwe

    • Hi Uwe,

      Thanks a lot!
      This cd player is based on the Sony KSS-213Q laser unit. If you need a complete laser assembly, those are usually referred to as KSM-213Q (or KSM213QCS). Keep in mind that in this case the Q version could make a difference.
      I have read some article somewhere on the internet what the differences exactly were, but I can’t remember nor find it anywhere anymore.
      If you need also the tray assembly, then I really have no idea where to find one.

      Mit freundlichen Grüßen! 😉

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