No sound out of left channel on Eros 2

[bradtsakeris]

Hi Dan and Paul,

I just completed my build and went to play a record. I am only getting sound out of the right channel. Any thoughts where to start with a diagnosis?

[Paul Birkeland]

How did the voltage checks go?

[bradtsakeris]

Hi Paul,

Here are the readings from the voltage check.

IA = 217.3v
IB = 219.3v
OA = 158v
OB = 147v
OC = 98.2v
OD = 141.9v
OkA = 97v
OkB = 140v
OkC = 1.61v
OkD = 2.3v

[Paul Birkeland]

That is definitely not a working set of voltages.  I would suggest reflowing the solder joints on the forward C4S board (other than the LEDs themselves) and post some build photos if at all possible. 

[bradtsakeris]

Hi Paul,

I re-soldered the front of the C4S board and am getting the following readings:

IA = 217.2v
IB = 219.3v
OA = 158.9v
OB = 147.7v
OC = 98.2v
OD = 110.2v
OkA = 97.4v
OkB = 115.2v
OkC = 1.62v
OkD = 2.31v

I am not getting sound out of either channel at this point. Thoughts?

[Paul Birkeland]

You can post some build photos if you like.

I receive quite a few Eros kits for repair like this, and 99% of the time I just have to reflow a few solder joints to get things running at spec.

[bradtsakeris]

Paul,

Here is the most recent picture of the C4S board with the most recent attempts at resoldering.

[Paul Birkeland]

That's a bit out of focus to really see everything.  To get all the terminals in focus, you'd need to have the camera parallel to the surface of the PC board and shoot it straight on.

Typically the problematic solder joints are the center legs of the MJE350.  Another problem arises when people don't see the LEDs lighting up, then decide that those are the problematic solder joints, then they reheat the LED joints until the LEDs are damaged, which then just adds another problem on top of what already exists.

It's also not uncommon for these soldering problems to cause 2N2222 transistor damage due to the operating conditions that can occur when the circuit isn't 100% operational.

[bradtsakeris]

Hi Paul,

Here is another picture. Hopefully this is a little easier to see. Let me know if there are any glaring issues before I rewire the board back the the chassis.

[Paul Birkeland]

I see a couple of joints in the top row of holes that look questionable.  If your iron has temperature adjustment, I would turn it all the way up.  Go ahead and reheat the center lug of each MJE350 and count to 5 to let the solder really flow out well.

[bradtsakeris]

Paul,

I have re-soldered all of the joints on the C4S and am still not getting sound out of the left channel. At this point I would like to see what other options are available to help. What is the process for either sending the C4S board back and having you take a look, or is it possible for a completed C4S board to be sent back to me and I can install it. Please let me know as soon as you can.

Thanks,
Brad

[Paul Birkeland]

You would need to contact Eileen (queen(at)bottlehead(dot)com about sending the entire kit in.  There could be something else going on off the C4S board that's causing these issues, so the most cost effective option is to send the whole kit in for repair.  If you'd like to opt for the repair service, please be sure to mention that we have worked on this on the forum, as we don't generally accept repairs without going through this process.

-PB

[bradtsakeris]

Paul,

Before moving forward with sending the kit in for a repair, I was hoping to see other things we could check. I am confident the solder joints are all properly soldered on the C4S board. The issue I'm having continues to be the voltage reading on the OD and OkB sections of the board. Aside from solder, what else could cause there to be an issue? Let me know your thoughts when you have a chance.

The readings I'm getting for OD and OkB continue to be in the 140v range.

[Paul Birkeland]

There could be a miwsire in the build underneath the board causing this.