SB3 volume output lower on left than right channel

[swaf]

Hi, I have a queation.

I seem to have more or less the same problem, one channel that is substantially lower in volume, and recently it has stopped working at all. However, I do not have a SB2 or 3, but a SB reiceiver. I haven't been able to find the SBR schematics anywhere, could it be possible that the same fault still exists in the SBR, although it has been designed and built approx 5 years after the SB3?

So I opened it up and I think I identified the caps. On them is printed 10/16s./9J9" so I think these are the 10 uF / 16V caps you were speaking of. The positive side is directly connected to the dac. Perhaps they used the same circuitry as in the SB2/3 here?

I haven't measured anything yet, but the suggestion to measure RMS to ground before and after the cap when playing a sine wave seems to make sense.

In the mean time, if anyone could provide me with a SBR schematic I'd be very grateful.

EDIT:

So I measured. I got 4.7V from the DAC's output signal on both channels. I got 0.8V output from the output caps on both channels. All seems fine so far. But one RCA connector measures at 0.8V, the other 0.1V. How is this possible? The components are very small and it's hard to see what happens to the signal after the output cap without schematic, probably an LP filter? But I don't think I see an opamp in there. Probably one of the smaller R or C's of the filter are defective, but this is nearly impossible to replace, they are so small. So I'm thinking of connecting both channels directly to the output, bypassing any defective component there might be, but also bypassing the LP filter. Good idea? Any other solutions?

Then there's only the question of which cap to use. Same value (10uF) as the stock ones, or a different value?

[swaf]

Ok, so I did some reading. I read the spec sheet of the Wolfson DAC. The output caps seem to be correctly oriented. So that isn't the problem. For future reference, I'm going to describe what steps I'll undertake to fix my problem and what their results are.

I'm pretty sure one of the mini components that make up the LP filter has failed, which is the reason why one channel is dead. My output caps are fine. Now I was wondering if that LP filter is really necessary. According to the spec sheet: in most cases, no. The DAC already has a built-in LP filter.

Quick fix is to bypass the filter and go directly from the output cap to the RCA connector, so that's what I'll do, once I have my mini soldering iron, still looking for a good one. I can solder, but I've never soldered anything that small.

Since I need to solder anyway, I was looking if there's a way I can change the output caps to something better (note that the spec sheet says to use high quality C0G caps, which the stock ones aren't). There are not many threads about modding the SBR, but there's one monster thread that I half read, and from what I gather it's not as easy as it seems. It requires constant tweaking and listening to the changes you made. While I like such a kinds of projects, right now I lack the time, and more importantly the audio equipment of high enough quality to actually hear such minor changes. And all I really want is to have my stereo sound back.

So, I'll simply bypass the LP filter and keep on using the stock caps. I'll let you know how that went in just a few days.

[Appalachik]

I have the same issue...

I have a similar problem... I own 2 SB3s and an SB2. One of my SB3s is outputting about 20dB less on the right channel. I have substituted the other Squeezeboxes into the system to confirm the fault. The faulty squeezebox outputs fine via headphones. I run this system in my recording studio through a Focusrite Audio interface, using toslink and configuring MixController to use ADAT as an optical SPDIF, routing the output either to my Tannoy main monitors, or to an Adam 2.1 monitor/sub setup. The setup lets me mute individual output channels, where I noticed another odd thing... muting the right channel works fine, but muting the left channel only diminishes its output somewhat, so it can still be heard. Seems odd to me and may be part of the same problem? Any ideas? If there is a full schematic of the SB3 available, I'd like to check it out and show it to my resident electronics wizard as he will most likely be able to fix the problem.

Thanks! Jenna

[fieldwolf]

Hi,

I have a Slimdevices SB3 classic which appears to have developed the same fault where the Left channel output is significantly lower than that of the Right.

I see eCo resolved this buy replacing Capacitors C16 (R-Channel) and C20 (L-Channel) with new 10uF/16v caps (Vishay 097 RLP 7).

As an electronics beginner, I take it that requires me to purchase new capacitors, solder out the old ones and solder in some new?

In which case, could anybody help to confirm the below 2 links the ones I need?

http://www.farnell.com/datasheets/415423.pdf

http://www.vishay.com/docs/28308/097rlp7.pdf

and so purchasing them from here is probably an ok bet?

http://uk.farnell.com/vishay-bc-components/mal209755109e6/cap-alu-elec-10uf-16v-rad/dp/1165518

eCo suggests soldering the new caps in with the negative lead towards the pcm1748 so I'll go for that.

For anybody experiencing the same problem but not wanting to open or solder their unit, am I right in saying that you could use the SPDIF or Toslink digital outputs and hook those up to a digital optical to rca analog converter that you can find on ebay?

I believe that bypasses the DAC in the SB where the fault but you would then be only as good as the quality of DAC you buy? I see ones from £10 to £100 so plenty of options there....but for those who just want their SB back in working order that should work?

Apologies for resurrecting an old thread and many thanks if anybody is able to get back to me.

[ralphy]

For anybody experiencing the same problem but not wanting to open or solder their unit, am I right in saying that you could use the SPDIF or Toslink digital outputs and hook those up to a digital optical to rca analog converter that you can find on ebay?

I can confirm that the SPDIF out works for me on an SB3 with this problem.

[fieldwolf]

thanks Ralphy.

Just to confirm - I went ahead and bought a cheap DAC off Ebay (£10) which came with Toslink optical cable. That has fixed my L/R balance problems.

I don't believe the sound quality is as rich as it was before which is probably due to the budget DAC I purchased.

I'm going to give the soldering the caps solution a go and will report back.

[lemmy999]

I know some have talked about it being difficult working with surface mount devices, but to be honest, I find it much easier than through hole parts. If you can obtain two soldering irons, just put one on each side and the capacitor will come off very easily. Good luck.

[mgraves]

Three of my five SB3s now have this problem. I've responded thus far by adding a cheap ($20) outboard DAC in one case. In another case I purchased an SMSL amplifier with digital inputs to power some speakers on our front porch. Nether are truly HiFi solutions, but adequate for the situations they address.

I'm considering an external DAC from Shiit Audio, or just getting inside to make the repairs on the third SB3.

With five SB3s still running converting to any other system is prohibitively expensive. I'd like to keep these going as long as I can.

[DonnLaurent]

Can you please share the specifications of your SB3?
What are the components for its hardware and what interface it uses for its channel?
What is its capacity to drive the channel in terms of devices and the Output current?

https://www.7pcb.com

[klotz]

Me too

SB3, Willy 230050630, right channel is very low. Jumpering C16 alleviated the problem, at least for one channel in the headphones. But I get no output now. Ordered some replacement electrolytics.

Also, all the though-hole pins had white bloom from the flux. I touched up the pins and scraped away the flux in most places, but I think it's not a high-impedance path anywhere anyway.

-- update --

Replaced the caps with similar ones, factory polarity. No longer crashes, but I have low audio in the right channel of my tube amp still, clearly unrelated.

[mgraves]

Over the holidays I came to own a Shiit Modi 2 Uber DAC. This overcomes the trouble with the analog outputs of one of my SB3s quite nicely.

I do think that I'll eventually go inside my remaining SB3s and replace the output capacitors.

[TP96]

New caps installed

Over the holidays I came to own a Shiit Modi 2 Uber DAC. This overcomes the trouble with the analog outputs of one of my SB3s quite nicely.

I do think that I'll eventually go inside my remaining SB3s and replace the output capacitors.

I wanted to thank everyone for helping me fix my SB3. I ended up using some non-polarized surface mount caps that fit perfectly. Here is a pic of the parts which cost $1.80 each when you buy 10.

[ralphy]

I just replaced the capacitors in my SB3 as well.

See the SB3 common faults over time thread for details and pictures.

[raichea]

I tried to switch on my SB3 a couple of days ago and the display didn't show anything. From the server, it looked as though everything was working as expected, but there was no sound even though the player was playing according to the web interface.

A quick google threw up the power supply as a possible candidate for the display issue. I took some measurements and the voltage held up reasonably well, even under load, so I was dubious. A known good supply brought the display back to life, however.

Assuming I was now up and running again, I then realised my SB3 had another fault. The left channel was much quieter than the right. I've no idea whether the power problem precipitated this other fault, but I hadn't noticed it before so it's a possibility.

Thanks to this thread, I was able to home in on the probable cause quickly. Measurements indicated that C20 had failed. Having tried a quick fix with a regular electrolytic and determined that was the problem, it also highlighted that the right channel was quiet compared to the now fixed left channel so C16 needed replacing too. I decided that as C21 and C23 are subject to similar waveforms, they may be on their way out as well so I decided to replace all four. I removed the headphone socket to make accessing C21 and C23 less difficult.

The hardest part is getting the old capacitors off the board without damaging the tracks. I managed to lift one track but, fortunately, it didn't break... certainly a potential weak spot now though. Someone recommended having two soldering irons to release both sides of the capacitor at once and this would definitely be less risky to the tracks, if it bit tricky with only two hands. Getting the headphone socket off was a bit fiddly, but easy enough with judicious use of a solder sucker.

I selected these capacitors as replacements - http://bit.ly/2ehag7K - as their endurance rating was better than most.

Thanks to those who came before me - it made fixing this a whole lot easier than it might have been.

I've attached the existing schematic updated with the SB3 component numbers. Note that the dual opamp has had each opamp reassigned to the opposite channel compared to the SB2 schematic.

Raichea

[vinnielo]

I've attached the existing schematic updated with the SB3 component numbers. Note that the dual opamp has had each opamp reassigned to the opposite channel compared to the SB2 schematic.

Raichea

Thanks for this amended schematic.
It made life easier when a bit of soldering work didn't quite go to plan.