Squeezebox Touch Power Supply Problem or a tale of 2 PSUs

[Richard]

Hi Al, thanks for the info. A bit of googling seems to agree with you about no sound difference, it seems to be that the psu is good enough as the Touch has further regulation inside, makes sense I suppose.

For anyone in a similar situation, I phoned Logitech and despite the psu being shown on their website it's definitely no longer available from them. Googling the Phihong part number on the unit gets us the specs but they no longer seem to do an exact equivalent.

So I chose another psu from RS and all is working well now including the infra red remotes on both Touch set ups. That seems to confirm remote failure was due to a failing psu in this instance. Perhaps sensitive circuits are regulated inside the Touch but the remote IR sensor may be run straight off the psu, just a thought.

Anyway, I went for RS 731-6002 £15 +vat which is a direct plug-in replacement with similar ripple and regulation,

5V 4A rating (original 3A)
coax cable with ferrite choke
5.5mm x 2.5mm pin round plug

Sounds great, no difference obvious on a comparison with my good Logitech supply, but I bought 2 as they are both a few years old now.

With all working well I thought I'd investgate the failure a bit more by loading the supplies a little and checking DC and AC with the meter again. I clipped the meter leads to the ends of 100R resistor and connected them into the psu output plug. That should load the supply a modest 50mA or 0.25W, not much, but the results were interesting. I used the 2VAC range this time as the 200mV range is erratic;

Good Logitech supply 5.1VDC and 2mVAC
Bad Logitech supply 5V DC and 238mVAC(!)
New RS supply 5.2VDC and 4mVAC

These were just cold readings so don't take them as Gospel but the bad supply was certainly obvious and worth keeping an eye on an old Touch!