opa 627bp in MHZS cd33

T, VIEWER,

U got any idea on the nipon chimi con oil cap in the picture (black)?
it is a film cap or electrolytic cap?

anyone kno0w the sound quality of this cap?

Dear friends,

I measured the readings by placing the RED probe on the base pin of the tube and the Black one on the ground screw located at the analog pcb.

I got very interesting but worrying readings.

For the tube closer to the RCA socket:
Cathode -- 63.4V
Grid       -- 62.6V
Plate      -- 96.7V
Heater    -- 5.4V

For the tube closer to the DAC
Cathode  -- 11.3V
Grid        -- 2.3V
Plate       -- 62.8V
Heater    -- 5.4V

What could be wrong with my CD?

CAT

Dear cat,
ur measurement when cd not playing right?

since your zener use 100v thus your plate getting 96.7V is normal (i'm wonder how come T getting only 54v?, may be he refer to another tube?))

But the diffential voltage is ~33.7V for tube 1 which is quite low, maybe this is 1 of the reason your dB may read low. Try check your cathod resistor value, is it correct when u change it back as u had cahnge the whole board or compare the resitor value with the original and see....

your 2nd tube differntial is ~50V which is normally use.... when we compare T, n my cdp which using this 2c51/6N3 tube normally they use ~40-50v voltage differences.

So i suggest u check your cathod resistor value  (compare with original, n measure the value see it fall in the tolerance range not?)

or if your other friend got the same cd u do the measurement then compare n look at the cathode resistor wheter same value?

Dear WINDWSS,

What I don't understand is the CATHODE part of tube 1 & 2. Tube one says 63.4V but tube 2 is only 11.3V. Shouldn't they be equal as each tube governs each channel?

Second, I use the same trick for measuring Voltage for measureing resistance value? Just switch the Multi-meter to measure resistance?
Sorry, I got a bit confused as you said Cathode RESISTOR.

CAT

Cat,

Since i don't have the schematic of your CDP as i'm using bada not cd33 so i'm not sure your 2 tube is for 2 channel or for 2 stage( stage 1 & 2).

If 2 tube for 2 channel then the reading for both tube should be similar but if is is for 2 stage then it can be very different.

cathode resistor is the resistor connected to the cathode the give the voltage on the cathode (they use voltage drop theory). V=IR

For e.g,

if the the cathode resistor is 10R and create cathode voltage say 5V at plate voltage 70V. When u accidently replace with 100R then, it will created higher voltage drop, then ur cathode voltage will read >5V.

Since u said u had change a new board, in case they put in wrong resistor at teh cathode side then it will change the cathode voltage....

hi alfcat,

I agree with windwss said that :
Since u said u had change a new board, in case they put in wrong resistor at teh cathode side then it will change the cathode voltage....


try to take the reading of the said resistors for both tubes.
you can see the reading of the resistors which marked on the pcb.

thanks.

Dear Viewer,

Would you please measure your tubes' readings as well? In that case, I can have a reference.

Many thanks.

ALF

alfcat.

ok!!! i will  measure it soon and revert you.

thanks.

alfcat,
reading as follows:
For the tube closer to the RCA socket:
Cathode -- 0V
Grid -- 102V
Plate -- 102.7V
Heater -- 5.9V

For the tube closer to the DAC
Cathode -- 0V
Grid --0V
Plate -- 102.7V
Heater -- 5.9V

thanks.

Cat,

I'm not there to observe, but how does your player sound? I hate to sound discriminating, but your measurements make no sense if you are getting failry clean sound. The circuit incorporated here in your output stage is called a cathode follower. I can't find a scematic, but if I were to guess, only one tube is used per channel like a buffer.

Viewer's measurements are dead on.

Please look up Duncan's Amp Pages, and you can query the 5670 tube and see a visual of the pinout and figure out if you are hitting all the right point and then give us new measurements. Unless you have a resistor that has drastically changed, your plates and filament voltages should stay the same between the two tubes.

Hope this helps some,

Blair

Blair,

This is what's been troubling me since I got the new PCB. The factory practically de-solder everything on my old pcb and put them onto the new one. My worry is that some of the components may already be burned or malfunctioned because of my terrible mistake.

I have the CD turned on but NOT playing. Will it be different if I let it plays and take the readings?

It looks like WINDWSS, t, Viewer and I all got different readings for our CD players.

WINDWSS post the diagram of the 5670 / 2C51 tubes somewhere. I followed the diagram and took the measurement. Will try to re-take the readings again later today.

My CD player doesn't sound right after it returns; especially the high frequency part ... sort of like distorted. I won't say that is a "clean" sound. That is why I keep checking on the S/N ratio.

CAT

Cat,

Your testing shld be correct as you reading make sense, but viewer's measurement may be wrong for chathod & grid voltage (it look weird), his reading on plate & filamet shld be correct.

We are now measure the idle volatge, if u play the CD then the voltage will change (flatuate acording to audio signal if not mistaken)

Hi alfcat,

I will be take  measurement again.

thanks.

Cat,

I think that there is some good advice coming in from other members, but lets take a few minutes and breathe. One thing I can tell you from working on tube gear all this time is that troubleshooting on the tube end is not always a good idea.

Try this. Take all associated signal wires off your new board so as the tubes are the only thing still connected. Not because you are damaging anything, but it removes several different possibilities. Now you simply have the jumper between the PS board and the audio signal board. Remove the jumper from the audio board end of the jumper and take your meter set to DC and test all the pins on the cable. Write them down in order of what you get. If the holes are too small for your meter, take a push pin and put it in there and use a alligator clip to clip your meter to the push pin. Now that you have established the voltages are good from your PS, take three different colored markers (preferably fine tipped). Begin by tracing the path of your high voltage trace all the way to the tube. Then do the same for your filament voltages. If I remember correctly, this should be around 6.3v on this tube. Note that the 6.3v should be AC, so you may need to adjust your meter to establish the correct pin for these voltages. Do not start at the tube as it is much easier to make a mistake this way because you are viewing the tube upside down when you look at it.

Now that you have your traces marked for the 6.3v and the 80-100v depending on how you modded the player, trace each path with your fingers and examine each component on the board. I know this will take time, but there is probably nothing but resistors in the voltage paths. If you are not certain about the values, remove one end of the resistor carefully as not to lift the contact pads. The value is clearly marked underneath each resistor. If you ohm the entire voltage path out and the values are all correct then you will need to either change tubes to see if they are the culprit, or begin to examine the signal path for bad components. Take your time, and have fun with this

If you are anything like me, you are about to toss the player out the window!

I hope this advice helps you to take a step back and learn instead of troubleshooting by changing parts. Not that resistors are expensive, but you can sometimes do more damage than good by swapping parts out.

Blair

Hi alfcat,

reading as follows:
For the tube closer to the RCA socket:
1. 5.9v
2. 0v
3. 0v
4. 101.5v
5. 0v
6. 101.5v
7. 0v
8. 0v
9. 0v

For the tube closer to the DAC
1. 5.9v
2. 0v
3. 101.5v
4. 102.4v
5. 0v
6. 102.4v
7. 101.8v
8. 0v
9. 0v.

thanks,

Hi alfcat.
revised reading as follows:
For the tube closer to the dac:
1. 5.9v
2. 0v
3. 0v
4. 101.5v
5. 0v
6. 101.5v
7. 0v
8. 0v
9. 0v

For the tube closer to the RCA socket
1. 5.9v
2. 0v
3. 101.5v
4. 102.4v
5. 0v
6. 102.4v
7. 101.8v
8. 0v
9. 0v.

thanks,

Dear Viewer,

That is strange. You have the readings > 100VDC. I just have pin 4 close to 100V. Pin 2 & 3 is just around HALF of what you got.

Another strange thing. You have 3 readings (> 0V) for one tube and 4 readings for another. I have 4 readings for both tubes.


CAT

Dear Friends,

To avoid confusion of which pin is which one, I drew an ugly diagram to show my final findings.

I TRIPLE check this time before I take down the readings. The readings in PURPLE are mine. The readings in RED are my friend's CD 33. The main difference is his Zener is the Original One while I changed mine to 100V.

What do you guys think?

Can anyone explain why the two TUBES got different readings? The most amazing part is one has FIVE readings but the one closer to the DAC only got THREE! Aren't they doing the SAME job for EACH channel?

CAT

Dear Blair,

I followed your advice and checked all the power cables going from the PS PCB onto the Analog one. They checked OKAY; closely matched the readings on the PCB.

I also took a very carefully reading of the tubes right now [see my ugly drawing of the tubes]. When examing the PS PCB, I realised that some of the OS-CON were not well soldered. I re-solder them before I took the tubes readings.

Are the readings normal? If they are normal, I don't need to go through all the trouble ... ha..ha... :

Tossing the CD out of the window? It should be okay if you do it in TEXAS, ha..ha... In Hong Kong, if I do that, I will be quite certain that someone will got killed down the road ..... That is why in Hong Kong we use a different term --- dump it into the sea.

CAT

[quote:eb98bdbed6="WINDWSS"]
Dear T,
then your CD33 circuit is a lot diferent from my BADA HD21. wehen my voltatge at zener =100v, my anode is the same =100v, grid & cothode will increase to ~45+.

ur cd33 is using 2 tube, is they use 1 tube for 1 channel?
my bada using only 1 tube (use for 2 channel)

when it zener =75v, gtid & cathode~28+v,

so the differential voltage is ~ 54-10.3 = 43.7v

my different voltage is ~47V[/quote]

Theres 2 x tubes in the CD33,  I have had a closer look and it seems that one tube is for the first stage supplying both Left and Right and the second tube is for the second stage Left and Right.
My measurements was for the tube in the first stage,  it has dropper resistors before the Anode.
Here is the measurements for the second tube

Anode 99/99V
Cathode 52/54.6V
Grid  51.8/54.3V
Filament 5.8v

Basically  each half of the triode is for Left channel  and other half of triode for the right channel,  this second tube has different voltages compared to the other tube in the first stage

[quote:0e81a2a876="alfcat"]Dear Friends,

To avoid confusion of which pin is which one, I drew an ugly diagram to show my final findings.

I TRIPLE check this time before I take down the readings. The readings in PURPLE are mine. The readings in RED are my friend's CD 33. The main difference is his Zener is the Original One while I changed mine to 100V.

What do you guys think?

Can anyone explain why the two TUBES got different readings? The most amazing part is one has FIVE readings but the one closer to the DAC only got THREE! Aren't they doing the SAME job for EACH channel?

CAT[/quote]

See my above post, if it makes no sense I'll try and explain better,  the bottom tube supplies left and right signal which goes to the top tube, the top tube also supplies left and right signal to the coupling capacitors

Your voltages do not look right,  we need to find the problem.
You seem to have some voltages missing,  
your filament voltages are ok
Your cathode voltages are missing
Your Grid voltages on top tube look too high and the Grid voltages on bottom tube are missing
Your Anode voltages look fine

[quote:57f0b07e77="WINDWSS"]T, VIEWER,

U got any idea on the nipon chimi con oil cap in the picture (black)?
it is a film cap or electrolytic cap?

anyone kno0w the sound quality of this cap?[/quote]

I'm not 100% sure but the black capacitor looks like a PIO  ( I maybe wrong)
Also notice it has a silver stripe on the right?   this is normally the side where the internal foil is connected.

Please be careful with the old PIO,  sometimes they can leak DC voltage if used as a signal coupling capacitor

Heres voltages for both of my tubes

Dear t.,

That is strange. We have FOUR CD 33 here that give off similiar readings. We don't have Voltage readings for Tube 1 Pin 2 and 8 whereas yours have. You have more readings for the second tube (closer to the DAC) as well.

I am just an idiot in this field. Does this suggest that there is actually something wrong with the CD 33 design? As you by-passed the Op-amp part, will this affect the tubes' readings?

I will be going back to China next week. I really hope to acquire the schematic for the CD33. Let's see if my friend up there can help. With the schematic, I think experts like you may give us more insight into this issue.

CAT

Dear Blair,

I re-solder several points in the PS PCB and re-run the unit for a couple of hours. I realised that the "distortion" in High Pitch maybe caused by me using the Telefunken EL84 tubes. They tend to exaggerate the sound too much in my ASL amp. When I change the tubes back to GE 6L6G, the problem seems to be gone.

Will continue to investigate when I have more time this week.

CAT

Hi Cat,

I'll have a think and try to post some things for you to try later, its 1:55AM  here and I really must go to bed

A schematic would be a very big help regarding fault finding so I hope somebody can find one.
I remember you saying in another post that your CD33 does not sound as good as it did using this new pcb,  I think this is because of those voltages :wink:

On a positive note my modified CD33 sounds beautiful!  lets hope we can sort yours out!

Just a quick question,  did you try fitting supplied Chinese tubes and measuring the voltages?

Dear t.,

I hope you have a good night sleep. I couldn't sleep well last night and ended up with an headache this whole day up to now.

I took the measurement WITHOUT the tubes. At first, I tried to do it with the tubes on. I place the pin / probe at the soldering point. Then I realised it is kind of dangerous. Therefore, I took all those readings with the tubes pulled out.

Will that make a difference?

CAT

dear Cat,

u had to put on the tube for testing..... it will make a lot differences....

ss

Dear Friends,

I just finished my FINAL (hopefully it is) readings. This time, I put the tubes back on. Not only that, I also tried out the different tubes I have.

You can see from the KEY I put down on the paper. There are TWO CD 33 for comparisons. First, mine using the Bendix 2C51 tubes. Then comes my friend's CD 33 with the same Bendix type 2C51 and finally the Chinese 6N3 tubes. They produced interesting and very different results.

t. or WINDWSS, can you spot any possible problems here with these readings?

CAT

Dear t.,

I compared our figures. I don't understand why the PS to both my tubes read only 5.6V instead of 5.9V. Is it critical?

Second is PIN 3 & 7 of the tube close to the DAC. Our readings is only around 2.3V or close but YOURS is 8.3V, which is four times our voltage.

What do you think caused such a huge difference?

CAT

Excellent mr Cat     those voltages are much better!  I now understand why you had 0v for a  lot of the pins,  without the tubes you only get the Anode and Fillament voltages.

As far as I can see your voltages now seem fine,  reason being my voltages are higher for pins 3&7  is because I adjusted the cathode resistors to compensate for the use  bypassing the op-amp.

Your 5.6v reading for the fillament is fine

1:10am  and I'm still awake again!

Your Bendix tubes maybe drawing more current on the fillaments, make sure the fillament regulator heatsink is not getting too hot  (tallest heatsink on the PSU board)

Dear t.,

Your wordings are really comforting. Glad to hear that finally my CD is at least okay.

As mentioned in the previous post, I re-soldered several points on the PS PCB before I get back the "normal" sound I have. I think the problem arise mainly because I switched to another soldering iron and I am not used to that tip.

Will double check on the Heatsink there. Thanks for your help! :wink:

Hi Cat,

No problem;) pleased to hear I could help.

I'm thinking what mod to try next,  theres a few more things I have planned.
I'm tempted to try hardwiring different tubes,  maybe something more popular than the 6n3

Dear Cat,

i agree with T, your CDP reading look ok....


the filament voltage 5.6V is ok but i had saw some article say that for 6N3/5670 tube the best result is when filament voltage ~ 5.9-6V (recomended by some audio guy).

Dear cat,

Below are some comment from the articles i read.

为了发挥6N3最靓丽的音色、减少交流噪音干扰，灯丝电压采用直流供电，并且不用6.3V，而是用5.9V-6V给5670（6N3）供电音质最好（这是一位胆迷通过实验得出的结论），

Dear WINDWSS,

My friends' CD 33 all got 5.9V. I don't know why MINE gives only 5.6V.

Is there anyway to "improve" the Voltage supply?

CAT

for that u need to check your PS to filament.

For e.g, refer the schematic, the diagram below is a supply to the filament, i can change the 6.6 zener diode to adjust the voltage supply to filament.

If your supply filament supply is AC normally they use resistor to control the voltag ethen u can change the resistor to obtain voltage u 1.

If your PS for filament is control by zener as in my diagram, then changing the zener will change the filament voltage.

So what u need to do is to check how's the suppy voltag eto the filament, if u can draw out a schematic of the circuit on this supply to the filament then it will be easier to mod.

The fillament supply in the Cd33 is done by a simple fixed 6v regulator.
You could maybe try a new 6v reg for the easiest or built a circuit using adajustable LM317  (LM317 is NOT a direct replacement and the circuit would need to be altered)
May also be worth fitting a taller heatsink anyway as a precaution

Hi,
Just a question to "t.", your super regulator board seems very interesting... could i have more information about it ? (is a pcb is available somewhere ?,..)
Thanks !

The super regs and just pcb's I use for the dac chip are available from here  http://www.at-view.co.uk/alwsr.htm

You will notice mine looks different and uses added components,  I removed the LM317 pre reg and implemented a VBE gyrator using a darlington arrangement,  it improves noise rejection

Thanks ! ;-)

Does someone have tried to change the KSS213Q by a KSS213C (sony original part) ?

Hi, T,

In case Cat, replace the 6V regulator, it is still the giving 5.6V, he could just use a 7v regulator with a 6V/6.2V zener diode right?

Hi friends,

Can you tell me WHERE is that 6V Regulator? Ha..ha.. I don't know where it is located on the PCB ....  :cry:

[quote:ca8466be6f="alfcat"]Hi friends,

Can you tell me WHERE is that 6V Regulator? Ha..ha.. I don't know where it is located on the PCB ....  :cry:[/quote]

http://www.hififever.com/forum/download.php?id=7690
Top left of board, its the one using the tallest heatsink,  it should be marked as 7806
In between big caps,  another hint is to change BOTTOM 4700uf  capacitor to a 8200uf 16v panasonic FC.
Don't replace the top 4700uf capacitor with a low ESR :wink:  4700uf Elna Starget or 4700uf blackgate is ok for the top one

[quote:5a566d74f1="WINDWSS"]Hi, T,

In case Cat, replace the 6V regulator, it is still the giving 5.6V, he could just use a 7v regulator with a 6V/6.2V zener diode right?[/quote]

Yes,  just as long as the 6.2v zener diode can handle the fillament current

Dear t.,

Oh, the 7806 is a regulator .... I see.

What do you suggest I change to? And you said I should change to a larger Heatsink for it, right?

CAT

Dear t,

Do you have more photos of your cat? It looks like we have some cat fans here as well.

KK Ho likes cats too.