Cmoy noob part2;) [56kwarning]

[thegeek]

Hi everyone

I finally got started on my cmoy.
I used a stripboard and the layout from here:
Layout Post
(the parts names are from the original chu moy article)



so....
I'm having a tiny bit of trouble

Edit, (forgot to add what I am having trouble with)
The power supply seems to work ok, thought it's not quite 4.5/-4.5, but that is a known cmoy issue I guess.
I can't get any sound out of it, the only thing I hear is perhaps a slight "pop" when I plug in the battery.
The opamp does get quite hot so I'm afraid I've fried it, but I'm hesitant to add in the opa2227 I have as backup before I know what fried the 2134.
Can you guys spot anything wrong?
I can't find whatever error I've obviously done.
_please_ excuse my soldering, I've never soldered anything before, so I've been learning as I go

Pictures:
Hires HERE

 

[Fresno Bob]

what seem to be the trouble

 

[thegeek]

sorry

forgot a few lines there;p
The post has been edited.

 

[nikongod]

chances are quite good that you have a solder bridge somewhere.

actually, it looks like the input may be crossing the bropken line to the output there? in the corner opposite your finger in the picture 726.

 

[Banfi T.]

You did that to your finger with the soldering iron?

Anyway, do you have a multimeter I guess, otherwise you couldn't report on the different PSU voltages. Get the shematic offline (i.e print it or draw it down) and start some measurements. First, isn't there DC on the output? (Very important you could srcew your phones if you connected the PSU accidentally to the output). Also, without power measure all the connections. That point (which should be) is really connected to that other? Check every connection...It is not a complicated circuit, you should have it in 20 minutes twice ('cause you are a beginner as you stated.)

 

[RnB180]

I cant stop staring at the bloody finger.

 

[thegeek]

Hehe, nah, not the iron, the battery connectors, the positive side of it is very sharp on the inside, managed to make it snag a pice of me

Nikongod: opposite, as in direct diagonal opposite?
Code:

[left] ________ |\ | | \ | | \ | | \O| <-- there? ---------[/left]

I already spent an hour trying to find errors, I'll go over it tomorrow when I've got some sleep(it's 23.43 here) (and I have a headache from the fumes

)
Perhaps I'll find it then.
One thing, my battery only shows 8 volts, is that sufficient?

 

[Banfi T.]

Quote:

Originally Posted by thegeek Hehe, nah, not the iron, the battery connectors, the positive side of it is very sharp on the inside, managed to make it snag a pice of me Nikongod: opposite, as in direct diagonal opposite? Code: [left] ________ |\ | | \ | | \ | | \O| <-- there? ---------[/left] I already spent an hour trying to find errors, I'll go over it tomorrow when I've got some sleep(it's 23.43 here) (and I have a headache from the fumes ) Perhaps I'll find it then. One thing, my battery only shows 8 volts, is that sufficient?

Oh, I love ASCII art! 8 volts is surely not enough, your battery is drained.

By the way I was so sleepy today, that I feel I woke up a hour ago or so. (We are in the same time zone

)

 

[thegeek]

I've spent a little time trying to find the error, but I can't seem to find it.
I'v measured the input pins to the opamp and I get 4.2 and -5.2 (using a brand new battery). Is that ok?
Is there anything I can do in addition to trying to find solderbridges (measuring ohm) and measuring the volt output of the power supply?
Edit: do I need to have the led in the loop for things to work?

 

[Pars]

Quote:

Originally Posted by thegeek I've spent a little time trying to find the error, but I can't seem to find it. I'v measured the input pins to the opamp and I get 4.2 and -5.2 (using a brand new battery). Is that ok? Is there anything I can do in addition to trying to find solderbridges (measuring ohm) and measuring the volt output of the power supply?

Take a look at this post, and also use the search function, as there are a ton of CMoy troubleshooting threads. A voltage difference of a few millivolts or tenths of a volt is normal, particularly if you have phones plugged in (don't use good ones until you are sure the output DC offset is manageable!). See the article on ground schemes on Tangent's site for more info.
Quote:

Originally Posted by thegeek Edit: do I need to have the led in the loop for things to work?

No, the LED is not needed.

 

[thegeek]

When I measure resistanse from the voltage input pins across the two upper cap's to ground, what should I be getting? (Basicall from the opamp voltage sockets to virtual ground) I get around 4.7kohm, is that ok?

 

[klappar]

Make sure your power input polarity is correct. Just finished my first cmoy and cooked a opa2134 because my multimeter wires were reversed... symptoms were the same, the chip became very hot. After that I bougth couple TL072-s to experiment with. Now running with fine with new opa2134

 

[thegeek]

double.

 

[thegeek]

I think you might be onto something there

Now that I look at it I do think I wired the +/- wires wrong, which might explain a whole lot

I have 2 opa2227pa's and also 2 THS4631d's(I'd need a dip->soic socket converter ofcourse), would any of them work as a drop-in replacement?
The red wire from the 9volt plug is the positive one right?

 

[Pars]

Red is positive. The OPA2227s should drop in (this is a DIP-8 package, I presume).

When you say Quote:

Originally Posted by thegeek from the voltage input pins across the two upper cap's to ground,

, do you mean the V+ and V- pins on the opamp socket (w/o the opamp in)? These will show charging of the PSU caps, so you should not see a steady resistance (as 4.7K) here, but near short, going towards infinity (M ohms) as the cap charges. If you see a steady 4.7K, that means the cap(s) are not actually connected