No sound on right channel (AKA: Apparently I must be a total newbie)

[Paul Birkeland]

Yeah, half the big PC board just isn't conducting.  Can you post photos of the top and bottom of the board?  99% of the time, this is just a cold solder joint, I suppose 1% of the time the wire from the "O" terminal is broken or not landing on the correct terminal.

 

[bigfatpaulie]

Thanks!  Hopefully we (you) are getting closer

I really appreciate all your effort and patience on this.

PS. Sorry for the crummy photos, it is hard to get a photo of it attached.

PPS. I also tested the continuity of the connections to board again.

PPPS. I've since re-flowed every point on the big board.  No change.



EDIT:  Here's something interesting.  If I put my headphones on with the amp powered up (but nothing playing) and I measure the voltages at OA and OB I hear static ONLY in my left channel, never in the right.

 

[fullheadofnothing]

https://www.youtube.com/watch?v=VgcPxdnjwt4

You can go longer than 2 seconds, and especially on the center of the TIP-50, probably should.

 

[bigfatpaulie]

Please keep in mind I've re-flowed ALL these solders AT LEAST three times.  At this point, no, they don't look perfect...

 

[fullheadofnothing]

I know they do not look perfect. That is why I posted a video showing what good solder joints look like and clearly showing the process to get good looking solder joints.

 

[bigfatpaulie]

I get that.  It's really the best I can get them to look at this point, however.  As I said, this didn't start out looking this way...  Keep in mind this isn't my first Crack/SB.  I've also built a Mainline and several ANK kits including the level 5 (https://www.head-fi.org/threads/audio-note-kit-dac-5-1-signature-nos-r-2r.793641/).

I may not have the knowledge to diagnose, but I have a good amount of soldering in my day and I have been working with electronics for 15 years.  I'm certainly no professional, but I really suspect there is something else going on in this case.

Is there any possibility, at all, that one of the transistors isn't functioning correctly?

 

[Paul Birkeland]

At least one of the center legs of a TIP50 transistor does not have a solid looking joint on it.  Try putting your iron on the pad/center lead, then count to 20, then pull it off.

-PB

 

[Jimb0]

I usually desolder my joints with a desoldering pump if I noticed anything that didn't look good. When I tried reflowing my joints sometimes they looked the same or worse so I always made a habit of doing them over. I just never knew you could reflow them by reheating it that's why I always did it like that. Not sure if it will help in your case, but I'd give it a try on the Speedball board if nothing else works.

 

[bigfatpaulie]

Thanks, guys.

Okay, I completely removed the big board from the amp and did the 20 second soldering iron 'hold' on every joint, not just the ones on the TIP50.  No change.

Here is an odd symptom.  I don't know if the amp was doing this before or just started as I didn't try it prior to today.

If there is music playing at the source and I power up the amp with headphones on, I hear the music FIRST come in on the right side then it quickly shifts to the left fully as the amp powers up, leaving the right side dead.  The best way I can articulate it is if someone was on the right of my then quickly moved to my left.

I don't know if that helps but that's what I am experiencing.

 

[Paul Birkeland]

It's a really, really bad idea to listen to an amp that doesn't pass its voltage tests.  You may end up being in the market for new headphones.

Can you post new photos of the top and bottom side of the big PC board?

 

[bigfatpaulie]

It's a sacrificial pair of old HD433's - I'm okay if they blow up.

I, again, will point out that each time I am testing the continuity from a different place on the board to the other side of the component to ensure continuity (IE, testing if the actually solder joint is conducting) AND measuring the resistance.  If it isn't 0 ohms, I redo it.

However they look, I would honestly bet my right hand that the solders are all working...

So I'll ask again, is there, however small, a possibility that a transistor isn't functioning correctly? 

PS, sorry but the bad photos

 

[fullheadofnothing]

Could you please remove the board and photograph it in focus and without backlight?

While the board is out, you could re-install the 3K resistors and confirm that the amplifier passes signal without the large Speedball board.

Also are you checking voltages after resoldering? You have not specified how you are determining that there is no change, and the only unchanged symptom you have listed is the dead channel.

 

[bigfatpaulie]

I, sadly, don't have the resistors anymore.  Like an idiot, I thought this was going to a simple upgrade...

When I say 'no change' I mean the right channel is still dead.

Wish I could get an answer to my question - is it at all possible that one of the parts has failed?

 

[bigfatpaulie]

Could I substitute film resistors to test?

 

[Paul Birkeland]

I still see cold solders on those TIP50 transistors.

Are you, by chance, using lead free solder?  What kind of iron are you using?  Heat and lead will be your friends for getting a good joint.

 

[bigfatpaulie]

Hello,

It's a Solomon SL-10 soldering station and it is "Rosin core Solder for PC wok".  It does contain lead.

I realize that solders look a little gray, but it is the photo and reflection.  In person they are all shiny. 

Are there any other test/measures I can do?  Or should I just start buying replacement transistors?

BIG BOARD:
OA: 103.1
OB: 148.7
G: 0
B+: 196.0

SMALL BOARD:
OA: 77.7
IA: 196.6
B-A/B: 0
IB: 196.1
OB: 70.6

 

[Paul Birkeland]

It's not the sheen or lack thereof, those joints just need a little additional solder.

A shorted transistor will measure very low impedance between a pair of legs.  In the absence of such a measurement, the transistor in question is likely working properly.

 

[bigfatpaulie]

I don't mean to be rude, but this is a little frustrating...  You said cold solder joints and in the manual it says: A cold joint will usually appear as a convex blob and be dull or even crystallized in appearance."

Now you are saying it isn't enough solder, which is different.

I'm confident that 'not enough solder' isn't the issue.  See the image - I've ONLY soldered from the underside of the board which means this is solder that has flowed down.  There is A LOT of solder...  Are there any other voltage test/results I can give you?  Is there another possibly aside a bad solder joint?  Like anything, however remote, at all possible?

Please.

 

[Doc B]

We all sometimes get frustrated when we are sure that we have done what has been suggested and things still don't work. I'm looking at that middle pin of the TIP50, and I have to say the first thing that comes to me is that I would reheat it until I saw that blob melt and create a fillet with the solder pad. Generally the best approach when reflowing a joint like that is to have a solder spool handy so you can add just a little bit more solder of it looks like it is necessary to get a fillet to the pad all the way around the lead. We're not trying to frustrate you, we are trying to help.

 

[bigfatpaulie]

That's the thing, please don't get me wrong: I really appreciate you guys trying.

But, truly, I can't help but feel after re-flowing the solder three times, then de-soldering everything, then re-soldering then re-flowing two more times - doing all that and each time I have the exact same issue...  Not to mention things like the TIP50's have been reflowed probably another 4 - 5 times and de/re-soldered additionally.

And does the shift from the right side to the left side not strike either of you are odd?  I mean, have you ever experience that, and if so was it a bad solder joint?

Also - can I use film resistors and remove the big board?  I realize they will get really hot, but I just want to see if I can get both channels working, even if for just a moment.

For your review before I reinstall the board yet again, how do these solder joints look?  Please note that I have only added solder to the bottom side of the board, everything on the top side had flowed though.