[tigger]

Yup it's a 1 legger. LOL, sound out of left channel only. I'm using the OPA 2132 opamp soldered directly to the board. The power supply works correctly but the amp section has a problem. I have been looking for information, but need some advice on where to find info on troubleshooting. I have checked for solder bridges, but can't see any.Which pins do I check with the DMM and what values should I get. The amp is a standard config with R5 populated using Radio Shack 0150 board gain of 11.
Any help would be appreciated.

 

[tigger]

Update. I found a suspicious solder joint and tried to redo it. Now I have no sound! Do you guys think I fried my opamp?
Next time it's dip sockets for me.
Does anyone know which pins show readings with the DMM and what voltages I should be getting?

 

[meat01]

I just built my first amp and I had the same problems you did. My problem was that the resistors were not going to ground. It was a silly mistake, but after I fixed that, it worked. Another problem I had was that my R5 resistor was not connected to the output. Good luck. You are half way there!

 

[tigger]

meat01

Thanks for the reply. I have ordered lots more parts and I'm going to try and get this thing going in the meantime. If it won't work, at least I will have learned better soldering skills.
One of my problems was using solder that was too thick, 1.2 mm. Now I have ordered some thinner stuff from Mouser.
I'm also looking for a smaller sharper tip for the gun. It's encouraging to know others have failed the first time! Another thing I have done is make a shortlist with part #s for all the neccessary parts for a Cmoy. Then I copied parts values onto the diagram shown on tangent's site http://www.tangentsoft.net/audio/cmo...ayout-0150.pdf I find this one easiest to use.
I do have one question though. Are the jumpers on the extreme left and right of the board "M" jumpers?

 

[meat01]

The jumpers on the left and right that cover 3 holes are jumpers. I made the mistake of making one jumper and skipping the middle hole, so r5 was not grounded. There should be 2 separate jumpers, so that r5 is electrically connected to r4 and the output.

I just made my second CMoy last night and I have a short somewhere, because when I first installed the battery, my finger happenend to be on the opamp and it got really hot instantly.

The Opamps are pretty tough, so I don't think you fried it. You probably just have an open circuit somewhere.

 

[tigger]

Quote:

Originally posted by meat01 The jumpers on the left and right that cover 3 holes are jumpers. I made the mistake of making one jumper and skipping the middle hole, so r5 was not grounded. There should be 2 separate jumpers, so that r5 is electrically connected to r4 and the output. I just made my second CMoy last night and I have a short somewhere, because when I first installed the battery, my finger happenend to be on the opamp and it got really hot instantly. The Opamps are pretty tough, so I don't think you fried it. You probably just have an open circuit somewhere.

I just ordered a new solder station with temperature control and smaller tips. This coupled with better techniques the next time around should produce a working amp. I've got parts to build Meta 42s as well but I want to get the Cmoy right first.
Sounds like we're at the same level of incompetance!!

Good luck troubleshooting the Cmoy, I think we learn more by making these mistakes rather than ending up with a working amp first time by a fluke.

 

[meat01]

Well I got my second CMoy up and running. More stupid errors of not following the instructions.

Tangent has made it perfectly clear in his diagram how to wire it and I keep soldering stuff to the wrong holes.

I too am getting experience to build a Meta42. I got my hammond enclosure for it and can not wait to build it, but I think I will build a few more CMoys first.

Good luck.

 

[puppyslugg]

Quote:

Originally posted by tigger It's encouraging to know others have failed the first time!

Don't sweat the 'failing part'. Just don't give up!