[Pars]

There are many Cmoy troubleshooting threads here. Example 1, example 2.

One thing that I always suggest for problems like this is to remove the opamp and ohm out each pin on the socket to ground, against the schematic (covered in both example threads). Then ohm out adjacent pins, and trace out the feedback loops. A problem here is more than likely causing your symptoms. Reflow your solder joints and make sure that component leads and wires are thru the board far enough.

 

[LazyAzN]

Ok. so I did the socket testing... here's what I got... (pin 1-4 from up to down on the left, 8-5 from up to down on the right [following datasheet]

Left
1. 99.6 kΩ
2. 2 kΩ
3. 12 kΩ
4. 4.7 kΩ

Right
8. 0 Ω
7. 2 kΩ
6. 1.9 kΩ
5. 12 kΩ

So first, one thing that irks me is that the l.out side (right side looking, left down)'s bridge is getting 0 Ω resistance, while the r.out side is getting 4.7 kΩ resistance, which means the R1 there is working. So this means I have to replace or resolder my R1 on the l.out side correct?

Second, pin 7 is connected to the 100 kΩ resistor, but yet I'm only getting 2 kΩ? This is not normal right??? I am sure that I did not use a 2 kΩ resistor there, but that's just weird... I am working on fixing 8 right now (originally it was receiving 4.7 kΩ, don't know what happened but ok).


Edit:
I reflowed the R1 that didn't provide any resistance to the bridge, and reflowed the pin that had 2 kΩ resistance (pin 8), now it works!!! KILLER...
Now to replace all that wire that I cut up... hehehe.

Thanks for all your help Pars, error401, breakfastchef, Footemps, InfiniteSymphony, MisterX (thanks for the layout!) and anyone else who helped (I forget the rest...)

Anywho, stick around a bit because it may be too early to be celebrating.

 

[error401]

You've definitely got some problems there. I assume you measured these values with no power applied? Here's what I see:

1. This pin is the output. If you trace the path to ground on the schematic, you will see that it should measure at most R5 + R4 + R3, typically 10-15K total.
2. This is probably okay. It should measure the value of R3.
3. This pin is the non-inverting input. In the schematic, it's connected to ground by R2. This value is probably too low - it should be ~100K with the default values. Leave the leads connected for a while so the charging of C1 doesn't affect the reading.
4. V- supply. This is okay.

5. It seems you're getting 12K for both input resistors. Did you change the schematic at all?
6. Probably okay
7. Output. Should measure R3+R4+R5, so this is probably too low. It might be shorted to pin 6.
8. V+. Definitely shouldn't be 0R to ground, you've got a short between power and ground - never a good thing. Find this first.

 

[Pars]

Quote:

Originally Posted by LazyAzN /img/forum/go_quote.gif Ok. so I did the socket testing... here's what I got... (pin 1-4 from up to down on the left, 8-5 from up to down on the right [following datasheet] Left 1. 99.6 kΩ 2. 2 kΩ 3. 12 kΩ 4. 4.7 kΩ Right 8. 0 Ω 7. 2 kΩ 6. 1.9 kΩ 5. 12 kΩ So first, one thing that irks me is that the l.out side (right side looking, left down)'s bridge is getting 0 Ω resistance, while the r.out side is getting 4.7 kΩ resistance, which means the R1 there is working. So this means I have to replace or resolder my R1 on the l.out side correct? Second, pin 7 is connected to the 100 kΩ resistor, but yet I'm only getting 2 kΩ? This is not normal right??? I am sure that I did not use a 2 kΩ resistor there, but that's just weird... I am working on fixing 8 right now (originally it was receiving 4.7 kΩ, don't know what happened but ok). <snip>

Yeah, I'd agree, something isn't right. First of all, are you sure you are using the correct pin counting (see attachment)? You start from pin 1 (lower left by the notch) and then count around, ending at 8.

Pin 4 (V-) that you show 4.7k for... was this a steady 4.7k? The power pins should be charging the electrolytic caps, and should start low and climb to infinite (or at least a very high resistance... electrolytics are slow as far as caps go). If it is steady, this would indicate to me that the caps aren't connected

Pin 8 (V+) 0 ohms is not good here... recheck it.

As for the rest of them, I agree with error401, although I don't think you have the pin numbering correct. What you show as pin 1 is probably pin 5, and should be 100k.

Left
1. 5. 99.6 kΩ
2. 6.2 kΩ
3. 7.12 kΩ
4. 8.4.7 kΩ

Right
8. 4.0 Ω
7. 3.2 kΩ
6. 2.1.9 kΩ
5. 1.12 kΩ

 

[error401]

Quote:

Originally Posted by Pars /img/forum/go_quote.gif Yeah, I'd agree, something isn't right. First of all, are you sure you are using the correct pin counting (see attachment)? You start from pin 1 (lower left by the notch) and then count around, ending at 8. Pin 4 (V-) that you show 4.7k for... was this a steady 4.7k? The power pins should be charging the electrolytic caps, and should start low and climb to infinite (or at least a very high resistance... electrolytics are slow as far as caps go). If it is steady, this would indicate to me that the caps aren't connected

I haven't read the first few pages so I could be wrong about this OP's CMOY, but the basic circuit uses 4.7K resistors as a voltage divider in the power supply. You'll measure 4.7K from either power rail to ground as a result

.

I was going to mention that the pin counting seemed wrong myself, but it's too hard to tell with so many other problems! Either way he's got a shorted power pin

.

 

[Pars]

A stock Cmoy (4.7k resistors) the caps will dominate the reading (at least every time I have checked one they did). Intuitively, the 4.7k resistors are in parallel with the caps, so you would think it would go to 4.7k and sit there? I dunno, I could be wrong, but the caps charging is what I have always seen.

Then again, its been a long time since I built a Cmoy, and most of mine used or were converted to either Sijosae rail splitters or TLE2426s...

 

[LazyAzN]

Quote:

Originally Posted by Pars /img/forum/go_quote.gif Yeah, I'd agree, something isn't right. First of all, are you sure you are using the correct pin counting (see attachment)? You start from pin 1 (lower left by the notch) and then count around, ending at 8. Pin 4 (V-) that you show 4.7k for... was this a steady 4.7k? The power pins should be charging the electrolytic caps, and should start low and climb to infinite (or at least a very high resistance... electrolytics are slow as far as caps go). If it is steady, this would indicate to me that the caps aren't connected Pin 8 (V+) 0 ohms is not good here... recheck it. As for the rest of them, I agree with error401, although I don't think you have the pin numbering correct. What you show as pin 1 is probably pin 5, and should be 100k. Left 1. 5. 99.6 kΩ 2. 6.2 kΩ 3. 7.12 kΩ 4. 8.4.7 kΩ Right 8. 4.0 Ω 7. 3.2 kΩ 6. 2.1.9 kΩ 5. 1.12 kΩ

Yeah sorry, I read the datasheet wrong (sorry error401!)

... Anywho, pin 8 actually ramps up slowly to 4.7 kΩ and then stops. I did reflow R1 so that now instead of 0 Ω resistance there is now 4.7 kΩ like there should be. I reflowed R2 so now we get ~ 100 kΩ as thought.. I used 100 Ω resistors for R5. As for the 12 kΩ resistance, I'm not fully sure why it ramped up to that, but so far everything seems fine (just loud but quite clear, probably due to the gain of R3). Just for clarification, I did break the TLE2426CLP, and thus switched it with 2 4.75 kΩ resistors I had planned to use for the RLED.

I just need to make sure when I resolder the wires i cut that everything works out fine.

Btw, does my edit not show? lol. (I'm very very lost on remembering what I did)...

Plus, this was without the battery.

 

[LazyAzN]

Um, one more question... What is the wire placements for the pins on the EVJ-C20F02D14 Panasonic pot??? I'm trying to use the placements from the assembly information and translate that into the information to the EVJC pot, but it's only giving me a left channel.

How I wired it (from the front)

1 - l.in
2 - Ground
3 - Ground
4 - r.in
5 - right (from jack)
6 - left (from jack)

*Apparently someone else had this trouble but never solved it...* Along with the fact that I don't have control of direction, it means that the pinout must be wrong.

I'm not good at comparing the schematic to this HeadWize - Project: A Pocket Headphone Amplifier by Chu Moy

 

[error401]

http://www.panasonic.com/industrial/...aok0000ce9.pdf

I think you have wired it correctly.

Looking at the front of the pot (the side with the spindle), they should be, from left to right:

1 - to amp 1
2 - ground
3 - ground
4 - to amp 2
5 - input 2
6 - input 1

 

[LazyAzN]

Quote:

Originally Posted by error401 /img/forum/go_quote.gif http://www.panasonic.com/industrial/...aok0000ce9.pdf I think you have wired it correctly. Looking at the front of the pot (the side with the spindle), they should be, from left to right: 1 - to amp 1 2 - ground 3 - ground 4 - to amp 2 5 - input 2 6 - input 1

Ok, something really weird is up now. Under load with the pot, my right channel is getting 4.7 kΩ resistance... on idle, now I get 9.7 kΩ resistance... while my left channel is getting 0 Ω resistance... Huh?... Oh well, back to making sure there are no shorts... I think I shorted an R5 with the out, thus why I get 9.7 kΩ on idle while getting 4.7 kΩ on load.

 

[infinitesymphony]

Here's a picture of the Panasonic pins, just to be 100% sure... I remember it was nice to have a picture as confirmation when I built mine.

 

[LazyAzN]

Quote:

Originally Posted by infinitesymphony /img/forum/go_quote.gif Here's a picture of the Panasonic pins, just to be 100% sure... I remember it was nice to have a picture as confirmation when I built mine.

Yeah, that's my exact configuration... I still don't get it though. Why is my left.input getting no resistance while the other is getting the resistance from the pot?

Update:
Now I get no resistance on both channels, which is a good thing now. But still I get no sound from the right channel. I've also checked the pot. The resistance to the input jack is getting varying inputs under 10 k ohms, which it should. The wires to the board have a resistance of 0 ohms, which means it's operating fine. Should I just get a new pot?

 

[Pars]

Quote:

Originally Posted by LazyAzN /img/forum/go_quote.gif Yeah, that's my exact configuration... I still don't get it though. Why is my left.input getting no resistance while the other is getting the resistance from the pot? Update: Now I get no resistance on both channels, which is a good thing now. But still I get no sound from the right channel. I've also checked the pot. The resistance to the input jack is getting varying inputs under 10 k ohms, which it should. The wires to the board have a resistance of 0 ohms, which means it's operating fine. Should I just get a new pot?

Hopefully you have some small miniclip leads for your meter

With it set to ohms (a scale that can measure 10k), with the control turned all the way down (ccw), measure from the ground to output 1 and then to output 2. You should have a very low reading (~ 0 ohms) on each. Now measure from input 1 to output 1, and input 2 to output 2. You should have close to the full pot value (~10k).

Turn the pot fully cw (full volume) and repeat. These readings should reverse (ground to output should now be full pot value, and input to output should be very low). If those are correct, then your pot is fine. Make sure that both pis 2 and 3 are grounded also (usually you just bridge these connections on the pot itself). One pin is ground for one channel, the other is the ground for the other. You can't wire one to the board and the other to the jack... they must be tied together.

 

[LazyAzN]

Quote:

Originally Posted by Pars /img/forum/go_quote.gif Hopefully you have some small miniclip leads for your meter With it set to ohms (a scale that can measure 10k), with the control turned all the way down (ccw), measure from the ground to output 1 and then to output 2. You should have a very low reading (~ 0 ohms) on each. Now measure from input 1 to output 1, and input 2 to output 2. You should have close to the full pot value (~10k). Turn the pot fully cw (full volume) and repeat. These readings should reverse (ground to output should now be full pot value, and input to output should be very low). If those are correct, then your pot is fine. Make sure that both pis 2 and 3 are grounded also (usually you just bridge these connections on the pot itself). One pin is ground for one channel, the other is the ground for the other. You can't wire one to the board and the other to the jack... they must be tied together.

Ok, I did the test (without the battery), and here's what I got.

With the volume at the lowest setting
Left output: 10.2 kΩ
Right output: 9.8 kΩ
Left output to left input: 10.2 kΩ
Right output to right input: 9.8 kΩ

With the volume at the highest setting
Left output: 0 kΩ
Right output: 9.8 kΩ
Left output to left input: 0 kΩ
Right output to right input: 0 kΩ

I didn't wire the ground from the jack to the pot, I wired it directly to the ground on the board. As for these numbers, the right output doesn't change, so I'm wondering if that may be the case. Also, these measurements are very off from what you stated... Uhh.

 

[Pars]

Quote:

Originally Posted by LazyAzN /img/forum/go_quote.gif Ok, I did the test (without the battery), and here's what I got. With the volume at the lowest setting Left output: 10.2 kΩ Right output: 9.8 kΩ Left output to left input: 10.2 kΩ Right output to right input: 9.8 kΩ

Where were you taking these measurements from? Right on the pot pins? For the first two, these should be from the output pins to ground. The measurements from the output pins to ground should be ~0 ohms at this point. The pot is a voltage divider (variable resistor). The input pin is one end of the full resistance, and the ground is the other end. The output pin is the wiper. With the pot turned all the way down, the wiper will be at (or near) the ground connection, and will be at the approx. same point electrically. As the pot is turned up, the wiper moves towards the input connection, and its resistance (to ground) increases correspondingly. You should be able to watch this with the meter as you turn the pot. The measurement from the wiper (output) to the input will be the reverse of this... as you turn the pot up, resistance will decrease.

Quote:

Originally Posted by LazyAzN /img/forum/go_quote.gif With the volume at the highest setting Left output: 0 kΩ Right output: 9.8 kΩ Left output to left input: 0 kΩ Right output to right input: 0 kΩ I didn't wire the ground from the jack to the pot, I wired it directly to the ground on the board. As for these numbers, the right output doesn't change, so I'm wondering if that may be the case. Also, these measurements are very off from what you stated... Uhh.

Is the ground on the pot connected to the board (both pins)? Left output to ground should be ~10K here.

See Potentiometer - Wikipedia, the free encyclopedia for more information.