右面 Channel 細聲 D? / Lower Output in Right Channel

記得上 CD 摩機班時 KK Sir 有題過 CD 33 有這個問題出現. 但始終開始老人痴呆, 唔記得點解決. 請問 KK Sir 可否在此指教一吓? 萬分感激 ...

From the CD modification class, KK Sir said the CD 33 got this stupid problem; the Right Channel gives off lower volume / output. This is exactly what I am experiencing right now. I swapped the cables, the LEFT channel will have lower output. Therefore it is a CD player problem.

What could caused the problem? I have check the soldering points of my modified parts, they are all okay.

CAT

Alfcat if you like i can guide you to search for the problem.
Al you need is a CD with a test signal between 400Hz or 2Khz, 1 Khz is just fine. And a multimeter. First measure the output signal for left and right channel with the testcd on play and the meter on AC/voltage. You must get a reading about 1000mV(1 Volt). Tell what your measurements are. Measure between signal and ground/shield of the output.

Ronny

Dear Ronny,

Just managed to dig out my Test CD.

I did the test using 1KHz at 0 db. The meter is a AC Voltmeter.

This is what I got. The 1Volt one is the LEFT channel and the lower one is the RIGHT channel.

What do you think?

CAT

CAT,

What are you mod for your CDP ?


Let me know the full story.

KK.HO

Oke , now it is confirmed that the right channel has a lower output and you have the right equipment.

Next measure the test signal between the jensen caps where you have connected the wires from the dac-ah and ground for left and right channel  When here the signals are even then the problem is beyond the caps other wise we must search near the DAC-ah. Let me now your measurements.

http://www.hififever.com/forum/download.php?id=8076

Dear KK Sir,

Let me divide the modification into sections:

1. I upgraded the Power Supply Section under your advice. Changed the Caps to BlackGate. Used the PHBY 1060 and alike. Please refer to Photo 1 attached.

2. Changed the Caps on the DAC board to Jensens, Nichcon / Muse. See Photo 2.

3. Added a Clock to the CD 33. See Photo 3.


4. Added the LITE DAC-AH board inside the CD 33 with its own Power  Supply. See Photo 5.

The problem exists long before I added the DAC board.

Please advise. MANY thanks.

CAT

Below i have the schematic of the analog outputstage, you need to measure ( same way you did above ) green points 1,2,3,4,5 of one channel and 6,7,8,9,10 of the other channel. If there is a difference between left and rights there you must search for the mismatch( defect).
The orange path is the way the audio travels.

Thanks so much Koifarm. I have to do it tomorrow as I had been struggling with my good friend's EL34. That project is really FRUSTRATING ....

Will come back to my own CD 33 tomorrow afternoon

CAT

Dear Koifarm,

Finally I got the chance to do the recordings today. These are the results I got.

Location:
1 --- 3.2   V             6 --- 3.2   V
2 --- 3.6   V             7 --- 3.6   V
3 --- 58.2 V             8 --- 59.0 V
4 --- 59.2 V             9 --- 60.5 V

From my limited knowledge I guess readings 3 & 8, 4 & 9 should be IDENTICAL, right? But now I measured more or less 1 Volt difference here.

I wasn't able to take location 5 as the capacitor is too close to the PCB.

I then changed Tube 2 (the one closer to the rear) to a Bendix and take another set of readings.

Location:

3 --- 55.7V      8 --- 56.4V
4 --- 56.1V      9 --- 57.0V   Again almost a 1V difference.

If I have ~1 Volt difference in the source, assuming 10 times amplification with the pre-amp and the power amp ... that will be a LOT of difference. Am I correct?

CAT

Alfcat are the measurements made with the meter on AC? Because values of point 3,4,8 and 9 are very high.
But the difference starts at point 3 and 8. So it is most likely that the 82 K resistors are the 2 you must change. One of them has a different value now. If you replace them use 1 or 2 watt types. If this not works you can replace the two 15K resistors. Because with yhe 82K and the 15 K you set the gain of the first tube.

Dear Koifarm,

These are the readings I obtained using the Multi-meter set to DC 200V. I have the Black lead clamped to the ground and the Red lead touching those points while the CD is playing.

My guess is the 82K resistor too. Unfortunately, I CAN' T locate where it is! It should start off with the color banding "Grey, Red ..." but there is no transistor with this color banding. Do you know where it is located?

I will try to search for them (should be in pairs) but taking out the Analog board later today. Many thanks.

CAT

Dear Ronny,

Should it be 56K instead of 82K. I got this schematics from our other thread in "Mystery of the DAC chip"

CAT

Alfcat . your right i used the wrong schematic the resistors who are suspect are the 56K and the 33K ones. When you remove the tube you can measure the resistance with the multimeter. So you can detect the defect one. The resistance should be the same for left and right channel. I do not know the excact position because i do not have a MHZS player at home. Just look on the text of the PCB or check the resistor color code or measure, they are near the first tube.

When you measure a audio test signal, set your meter to AC. This reading you get is then only the audiosignal without the superposed DC voltage.

Dear Koifarm,

I see. I will remove the tubes and check the resistance of the resistors with the multi-meter. Anyway, I would like to change those resistors for a long time ... this is a good chance / excuse for me.

I think I can trace along the path once I got the Analog PCB out. The board should be two layered, I can't see all the paths just by looking down. The worst case is I check their color bars. MHZS managed to print most of the values on the PCB, that is a good point.

Oh, I now know the difference between testing the CD using AC voltmeter and taking the DC readings. Many thanks along the way. Hopefully I can REALLY enjoy the benefits of my CD 33 tonight after changing the resistors.

Been working on my colleague's EL34 Amp for the past three weeks and finally got it done. Will turn it on later this afternoon to see it is good or not. Really enjoy constructing these toys now.

CAT

Dear Koifarm,

Really depressed. :cry:

I checked the resistors without the tubes on. They gave normal 56K, 33K readings. I thought perhaps their resistance change after they got heated up ... Anyway, I changed ALL the 56K and the 33K to RMG 1W.

However, the problem still persists. The DC Voltage difference remains the same.

WORST of all, the CD Tray starts to have problem. The Lens keep popping up and down and so often can't read disc. Sometimes, it won't open the tray and sometimes it says NO DISC. As I have spare lens units around, I changed the Lens unit and the flat cable as well. Not working. Only once in 5 trials I can get the CD running.

What could have caused the CD problem?

CAT

When this happen it is a pitty. Check if the lens is clean. And be sure if the flatcable is installed right.

About the measurements do not measure DC but AC with the testsignal on. The DC is not interresting. Please tell me your readings at the several points.

Hi alfcat,

I think your cd-33 sony's leaser head system is locked.
I also have this problem before.
I find a solution for it by this web site:
http://www.iwdiy.com/ShoppingMall/download/kits/intro-sony.htm

hope to help you.

thanks.

Dear Koifarm,

I don't have the Probes to test the signals / voltages at particular points. I need to get them maybe tomorrow. I can only connect my AC volt meter to RCA outs right now.

The Lens unit is new. I have three of those around and I tested each and every one already. I also have TWO flat cables and I also tested them as well.

Instead, I think it may be the cables that connect to the Analog PCB. Either the soldering points or the black cables got problems. Each time I remove the Analog PCB, the CD Tray got problems of all kinds.

Thank God, after settling for one day, the CD is playing again now ....

I think I will change the remaining 33K, 1K and the 470K resistors as well. See if the situation can be resolved.

One difference I really do noticed. I used RMG for the 33K 1W and the 56K. I can definitely hear more details. Some "minor" sound is now more obvious.

CAT

Dear Koifarm,

I managed to make my own tools instead of getting it from a hardware store to take the measurement.

Playing the same 1khz CD track, this is the reading I got with the AC volt-meter:

Tube 2

          Pin 2 --- 0.7V (barely)
          Pin 3 --- 0.7V

          Pin 7 --- 0.9V
          Pin 8 --- 0.9V

I think Pin 2 should match with Pin 8 & Pin 3 should go with Pin 7. There is a significant difference of 0.2V for the channels.

Attached are the photos showing the Resistors I have changed.

The TWO 150ohms are next to Tube 2.

I intend to change the SIX resistors on left and right of tube 1 as well.

I can not recall the 150 Ohm resistors. May be for the filaments power supply.

The 470K resistors you can change but now you can measure AC voltage i think may be the problem is the DAC. Please measure again the testsignal in AC at point 1 and 6 and before the jensen capacitors.

Dear Koifarm,

I was too tired after going to a funeral service yesteray.

Today, I changed the 33K, 470K and the 1K resistors for BOTH channels.
I also changed the tube socket to a gold plated one.

Thank God.... the problem is gone. I used RMG for the 470K and the 33K but only DALE is available for the 1K one.

I also changed something on the DAC-AH. Capacitors changed to Philips and the I/V  resistors to RMG as well

Now, when playing the 1KHz 0db track, all readings on both channels give close to 1V AC.

I am now listening to it and see how impressive it is.

Many thanks throughout the whole process!  

CAT

hi alfcat,

good job.

thanks.

Dear Viewer,

Did you say you moved? All settled?

How is your new home? More room for Hi Fi?

CAT

HI ALFCAT,

All settled
no more room for hi fi. i set it in living
condition for listening is quit good.

thanks.

Dear Viewer,

You now put the Hi Fi in living room?

My colleague just gave me a "electric" cable for connecting my CD to pre-amp, trying to poison me. Very good details ... from Audioquest.

If get in HK, > HK$ 2K. We got it from Mainland ... RMB $850 only. The difference is the RCA plugs.

CAT

again, it is poor component!

Dear Accphoto,

You mean the Chinese stuff is rubbish?

I haven't got the chance to listen to the original Audiquest one but this Chinese one gives pretty good details of music, compared with ordinary inter-link cable around $ 1K

CAT

Well done, Alfcat. =D>

I am working on a new projekt. Building a OTL amp with 6C33C-B tubes.
I have 20 pieces of them. I looking at several schematics still i have not found the right one.

cat sir

This is a fake audioquest cable.

DualXeon 兄,

這個當然啦. 賣的也說明是抄 AudioQuest 的. 但介開條線,係真係 AudioQuest 線材. 而且這個 Sales 是相熟的. 他一開始就講明是什麼料 ...

科技就一樣, 重點是平價 RCA 頭.

CAT

Thanks Koifarm for all your help !

What is an OTL amp?

CAT

cat sir

check email.

DualXeon 兄,

Replied your mail.

CAT

OTL amps do not have a outputtransformer. The tubes drives the speaker directly. I have some link on OTL and the schematic i like to build.

http://www.audiodesignguide.com/my/index.html#MY_OTL

Dear Koifarm,

Does this mean that the tubes have to have enough power to drive the speakers? Or else, the choice of speakers will have to be limited to those that have low resistance (= high impedence, right?)

CAT

With the above schematic you can drive normal 8 Ohm speakers and the amp is tested with 1 Ohm. Output power is 20 a 30 Watt at 8 Ohm.

http://www.currants.info/chinese ... w-gf/Rv-GM%2020.htm

Dear Koifarm,

How is the sound compared with the others?

I always thought that Tube Amp has to have a Output Transformer. Can you tell me what is the good point of skipping the Output Transformer (except saving the cost)?

CAT

An OTL amp does not sound like a tube amp, it is very linear and has maximum detail. It sounds less warm. But placement and detail is the best you can find. There is a design where you can build a 2 x 30 watt OTL amp for HK$ 3000. Look here.

http://www.audiodesignguide.com/my/index.html#MY_OTL

Dear Koifarm,

Hmm... sounds interesting. A tube amp but really doesn't sound like one. So this OTL will be closer to Transistor Amplifiers, right?

If I like simple vocals, this won't be the perfect one for me. But if I like something more complicated e.g. orchestra, this will be a better choice. Am I correct?

CAT

[quote:00bc7a9eed="alfcat"]Dear Koifarm,

Hmm... sounds interesting. A tube amp but really doesn't sound like one. So this OTL will be closer to Transistor Amplifiers, right?

If I like simple vocals, this won't be the perfect one for me. But if I like something more complicated e.g. orchestra, this will be a better choice. Am I correct?

CAT[/quote]

Yes, you are correct.

If you like vocals just take dynaudio speakers. I made them myself with dynaudio carspeakers. MD130 tweeters, MW150 mid/bass and MW170 woofer all in closed enclosure. The best i heard, used it now for 8 years.
I was stupid to sell them a half year ago. I am now collecting new dynaudio units to build them again. Everthing that comes near my dynaudio speakers are ready made dynaudio speakers cost more them HK$ 60000 a piece. The cost to make them self is about HK$ 10000 for 2 speakers.

HI ALFCAT,
DID YOU BUY THE CAYIN CD-15A OR CD22 ??

Dear Viewer,

No chance. Either it is SOLD or .... the seller is a bit suspicious ... same person, many login names selling the same thing

CAT

alfcat,

不要緊,等下可能會平少少都吾定,不用心急.
可能 cd-17a 會平,到時可買 cd17a 好過買 cd-15a.
他不買 cd-15a,可能到時祗可以買 $1.5k 都不一定.

Dear Viewer,

Yeah, I just hope my CD 33 won't die before I can get a better one. After all, this CD 33 had gone through many "battles" (modifications) and its design, especially its PCB is not good for this purpose at all.

CAT

Hi alfcat,

I found some cayin cd22 and cd15a listed for sell in review33
i suggest you chose cayin cd-22 because the film caps for outup are used by
Multicap.

thanks

Dear Viewer,

Thanks for your information. Just upgraded my Matisse with Jensen caps. Will have to save up some $$$ for the Chinese New Year. Let's hope my CD 33 can survive for some more months.

I will post photos of the Matisse later this week. The pre-amp still hasn't reach its normal level yet. Just ran in for 20 hours only.

CAT