MHZS CD 33E static in left channel

Hello forum!

I have recently purchased a MHZS CD 33E from another guy here in the US, and the issue he presented to me was that it made a slight static sound in the left channel. I bought this unit shipped for $150 USD so it was too good of a deal to pass up.

Well, I got the player home, and it certainly is a nice sounding player minus the static sound that is intermittent in the left channel. I started my journey by replacing the original op amp with the brown dog adapter and a few AD823ANs. I got nothing, so I changed the 5670s in the player with another pair still to no avail. Then I replaced all the 4700uf caps and the 1000uf and 2200uf counterparts on the tube board. Nothing. I changed the relay down by the output and the 100uf cap by the tubes. Nothing. Then I replaced all the .33uf tubes with high tolerance poly caps. I am still experiencing the static in the left channel.

I have no idea where to go next. Do you have any suggestions? Also, does anyone know where or how to get ahold of MHZS customer relations if the DAC chip is the culprit?

Thanks for any information regarding this player, and hello again.

Blair

Dear Blair,

Me and a couple of guys here all got CD 33 and we did a lot of modifications to the player. However, we never encountered anything like what you experienced.

You said Static Sound in the left channel, so I assume it is a continuous sound. So it is there once you turn on the machine and stays there no matter what, right? I am not an expert here ... is the sound like "dee ... deee... dee.." or something else.

As I have said, I am not the expert here ... I will see if I can check it out for you with some other guys around. Could it be the problem of the tubes? We changed those Chinese tubes right after we got our machines.

Hello Alfcat,

Here is a list of the components changed so far as mentioned in the previous post:

1) I changed all the 4,700uf caps with better caps in the PS and the DAC/tube board

2) I changed the .22uf caps in the 120v line filter

3) I changed the 2200uf caps and the 1000uf caps across from the 4700uf caps

4) I changed the 100uf cap next to the 5670 tubes along with the other two 100uf caps on the PS board.

5) I changed the pause signal relay next to the analog out

6) I changed the tubes to another pair of NOS GE/JAN 5670a.

7) I resoldered the tube sockets and hit some of the major solder joints to insure they are clean and in good contact.

8) I ungraded the opamp.

What I did last night was played with the ribbon wire leading to the pickup and wiggled the pickup around. It cleared the issue up for about an hour, but then the static came back. It is an intermittent static that sounds like a bad contact or a cap failing in tube gear. I read that the 213C and the 213Q pickups are interchangeable. Is this true. I can order an entire 213C assembly for less than US $30 here in the US. After that, I think I'm going to give up and sent it to the next unlucky guy to torture him

Thanks for any information,

Blair

各位大哥,

有無人可以幫到這個西人哥哥呢. 佢個問題我都好想知點樣解決.

English Version

Dear Brothers,

Anyone has any clue to the problem mentioned above by Blair? I am very interested in this issue. Hope some of you can shed us some light on this issue. Many thanks.  :wink:

Okay, after all the upgrades and changes it turned out to be the DAC chip. I removed the MHZS cover and the chip pulled itself away from the board. I ordered a new chip for a whopping $4.00, and soldered it in. Bingo, problem solved. There was apparently a cold joint in the DAC. I will warn anyone wanting to free their little DAC chip from the epoxy and the cover, the epoxy will pull that chip right off the board, so unless you are planning of replacing the chip completely, do not pull thecover. Anyway, thought you guys would want to know this.

Blair

Blair,

I am glad that you finally figured out what the source of the problem is.

Happy DIYing all the time

CAT

Hello Alfcat,

Could you please list all the mods and parts you have done to your player and rank the significance of each mod. I changed all my caps out, but not with the "best" grade caps. I can get a full set of ELNA caps for less than 20 USD so I'm wondering of this is worth the extra effort. Your thoughts?

Blair

Dear Blair,

Actually my modiffications of the CD 33 were posted on this link. I think I use 95% or so English, so you should be able to follow what I went through.

http://www.hififever.com/forum/viewtopic.php?t=1520&postdays=0&postorder=asc&start=0

I think the MOST significant changes was actually the first few steps. I replaced the Chinese tubes with first the WE 396a ... everyone can hear the differences. Then I further move it to Bendix 396a, even better.

Second, I change the OPAM to BB 2107. The 2604 is nothing compared to it. Next, I gave my 2107 away and used a pair of OPA 637BP. More or less the same. As the 2107 is not around, can't compare any more.

I then changed all the major caps. If you follow the link, you will realise that I am actually a Social Sci boy who knows nothing about Electronics. I can't even read Electronic Circuit board diagrams ... I just use my logic and my very basic knowledge in Electronics. I made one or two mistakes throughout the whole process.

Finally, I changed the clock; using a clock with a PCB. Very mild improvement, though it is audible. Luckily, it is just HK$ 200 (US$ 30).
For the clock changing part, please follow this link:

http://www.hififever.com/forum/viewtopic.php?t=1553

I hope everything is clear for you. If you need anything translate back into English, I can do it for you as well.

ALF