A Confused streaming system - Mutec / SOtM Ultra

[zdenes]

I tried the tx-USB ultra once with a PH SR3 but the power supply developed a problem. A technician fixed it and said that it cannot be completely ruled out that the problem was caused by the unit it was powering (the tx-USB ultra). So I am reluctant to connect anything else than the SPS-500 now. Hopefully, my unit will be replaced in Munich next month. Then I can do more testing.

What went wrong with the PH SR3?

I run my sMS-200ultra and tX-USBultra with two PH SR4 and they work very well. As I understand the SR4 uses the same regulator as a SR7 just less amps (2A at 5, 7, 9 or 12Vdc).

Well, I was hoping that I wouldn't have to write down the story as it is long and boring   , so I will try to keep it short and simple. 

After receiving my tx-USB ultra I changed the voltage internally to work on 12V because I have the fixed voltage SR3 and JS-2 that powers the SMS-200 ultra but it has two outputs and also can be used with a Y cable, and the SPS-500. So I was hoping to do a comprehensive PS test with these three. 

As I said above, the unit didn't work reliably with the SPS-500 (strange in itself) but seemed to work a touch more reliably with the SR3. Still, it didn't fully solve the connectivity problem. 

As the problem is always finding the USB device (getting the 'USB handshake'), a friend suggested trying a USB Y cable such as Kingrex with a 5V external USB power supply. 
He lent me such a cable and it did work for a day or two, so I thought that it solved the problem, although it is still not normal behaviour from the tx-USB ultra. 

So after a few days of seemingly troubleless operation - during which time I restarted the system about 4-5 times - I thought it's time to test the SQ with different power supplies (before that, when the SR3 was in use, I was concentrating on getting the system work, not so much on SQ). 

So I reconnected the SR3 and the device couldn't connect again. Strange, I thought, as with the Y USB cable the whole thing seemed to have worked for days before that. Then got the SPS-500 back and again things work fine. At this point I had a feeling - I don't know why - that the SR3 was not outputting the right voltage. I checked it, it was only 7.5V. A few days prior to that I measured it and it was 11.8V. So three things could have happened. 

a) The external 5V on the USB cable somehow found its way back to the power supply and caused damage to parts.
b) The tx-USB ultra itself is causing trouble and resulted in the damage - unrelated to the USB external power.
c) Just a coincidence. 

In order of probability, I think it is a > b > c but even in case 'a', that should have happened if the tx-USB ultra had been working fine. 
The technician who repaired said that the SR3 doesn't have much protection for 'adverse behaviour' of the unit is is feeding or overheating or anything like that. 
 
Now, the SR-3 is fixed, some parts needed to be replaced, luckily it didn't cost much but I'm reluctant to try again. 

BTW, the connection problem surfaced again even with the 5V external power. So I removed the USB Y cable and now I just use a standard USB cable. I also changed the unit back to 9V. 
The most reliable operation seems to be at 9V and the Wireworld USB connecting the SMS-200 ultra to the tx-USB ultra, but this is neither perfect nor acceptable anyway. 

I tried two different servers, two different NAA devices, many USB and ethernet cables, installing the SOtM OS on a new microSD, reinstalling HQPlayer and even removing HQPlayer from the mix and use the SMS-200 ultra from and attached pen drive. And a few other things. Nothing worked for more than a day or two (or not at all). 

Two knowledgeable technicians (one who fixed the SR3) suggested that it could be a faulty capacitor in the tx-USB ultra some other parts that don't work reliably. 

SOtM is very good at following and guiding my quest but it seems they will have to look at the unit eventually.