Luna - Left Output Dead

[maakbowie]

Hi
Dug out the old Luna card and been using on Win 10 for a few months and i pulled up some old songs to mix.
Running well, even on lowest latency setting.

Left Output Channel just stopped working and cannot figure out if the card has died.
Both chanels show meters on my daw (reaper) and scope software. Checked scope routing, swapped left and right out etc
Cable fully checked and correct. swapped left /right wiring, changed cables etc Analog amps, spkrs/phones checked.

Any ideas? Anything I can check on the PCI board?

Scope v 5.1.2709-x64
Windows 10 Pro. V 22H2 64bit
Intel Core i7-6700 3.4GHz. 32Gb Ram
Creamware Luna / Z-link / A16 Ultra

[valis]

Check the caps

[maakbowie]

@valis What do I look for? Bulging? They are looking ok as far as I can see?

[astroman]

Did the fail happen in the middle of a session without plugging the output connector ?
If it has been plugged frequently, the socket is worth checking.
It‘s the upper one of the 2 TRS sockets and you may solder a temporary cable to the big connectors on the backside.
(the 2 big spots at the end of the socket carry the signal, the front one is ground)

If there‘s indeed so signal on the left channel‘s socket, things may become really tricky.
Easiest (if your Luna has 4 caps next to the in/out sockets) is to exchange the 2 caps of the top connector.
Then the right channel will fail and you know which cap is dead.
You should be able to handle careful soldering, though.

Replacing the 5532 opamp or AKM converter is a completely different challenge.
I wouldn‘t do it, but choose another output option instead. S/PDIF or a Luna box.

[maakbowie]

@astroman Thanks for the answer. I will check the bottom of the board.
It did not hasppen in a session. Its not used much. The trs output cable generally stays unmoved and plugs into an amp for monitoring.
The zlink and A16 ultra stll work.

[garyb]

try a new adaptor. you are using a stereo plug in the Luna, no?

[valis]

try a new adaptor. you are using a stereo plug in the Luna, no?

Good point, start with the simplest things in the chain to test.

[maakbowie]

@valis @garyb. Yes TRS y cable to 2 mono Output 1 and 2. This is the first thing i tried and made up a new custom y cable.
I even wired an open plug and connected wires. Also all my plugs test with meter correctly.

So connecting directly to the solder behind the output socket (as mentioned by @astroman above) gets the same results so its not a problem with the socket internals

HOWEVER I have discovered there is a tiny amount of left signal. I thought it was crosstalk but isolated hard left panned sigmals shows up theres definitly a very low left signal there

[valis]

Caps and solder connections

[maakbowie]

Are you meaning the four small metal cased caps running along behind the I/O sockets on the underneath of the board? or maybe just two of them by the output socket?
should i just unsolder and resolder? or just heat uo and reflow the solder?
If this is even what you mean

[valis]

I don’t have a Luna, but you would visually inspect and then (if possible for you) measure their capacitance, to determine which may be faulty. Broken/loose solder can also cause this issue. As can MOSFETs and opamps/transistors.

[astroman]

It‘s the top 2 in the row of caps you mentioned.
Just unsolder and then solder in switched order, which will make the left channel come back... IF the cap is faulty or connection was broken. In the latter case both channels will be up again because you healed the broken connection.
That‘s a relatively simple operation because the pads are large and accessible.

The next candidate would be the 5532 opamp in the same area. It‘s a tiny smd version...

[valis]

If I were to desolder, I would simply replace all the caps. Either both sides will work, or you will find out that wasn't the issue and not have to worry about the caps in the future as they're aging anyway. Especially if you don't have an easy way to desolder/resolder.

[maakbowie]

Ok so I have the caps off but I dont think I can swap them as the way they are soldered from the top and underneath the cap itself makes it very difficult to solder or see if it is soldered properly. Also the legs dont fit the hole spacing to solder in the traditional way through the holes. I think the best is to replace the caps but unsure of type and how to read the markings.

Can anyone help?

They are all cased in metal. Most of them follow this format. Three lines of text:
25
47
6v

[astroman]

Dunno about the 25, but 47 is a common capacity value (microFarad) and 6V suggests voltage.
Which results in middle row capacity and bottom row voltage.
The caps are SMD types supposed to be applied to solder pads.

The original ones are a pain to solder by hand, but a similar style version with contacts sticking out a bit from the plastic base should be easier to handle.
Probably best to first tin pads on the circuit board and cap contacts separately and then apply a lot of heat to the cap contact‘s end...

[garyb]

wouldn't try to solder surfa
ce mount without the knowledge or equipment. i'd take it to somebody who can do it.

[maakbowie]

Although the existing caps are surface mounted, there are also holes on each connection where they could be mounted through the board.

[astroman]

If you have to deal with holes, this thing is really useful:
https://eleshop.eu/desolderingstation-zd-915.html
It‘s crap from a professional pov, but does a good job on occasional use.
(same item is sold under various brands)

[maakbowie]

YAY. replaced the two caps on the output and the Luna works both chanels now. Thankyou.