Well, I found a replacement but it seems that does not fully do it: PMIC - Linear (LDO) Texas Instruments LP2985IM5-3.5/NOPB
This has basically the same data on its datasheet as the original Torex part. Both are designed for 150mA but to me it looks like the circuitry behind the regulator actually draws considerably more. After doing the replacement, I found that this poor little chip heats up beyond 100°C in any operation mode. Might be something else wrong in the circuitry but the good news here is that the Touch actually powers up and is usable for the first time since I got it. Besides a half-defective line in the lower region of the display, everything appears to work. I assume this wouldn't last long though. Once the unit is assembled back together, and with the display right on top of it, there is no way for that heat to escape so it will build up until the chip blows. Maybe something else on the board took damage when U25 was blown. I found evidence of somebody meddling with the EEPROM, it was apparently resoldered. Also looks like the CPU was reflowed. While all this was done with care and no obvious screw-ups, something must have gone wrong later. I took some pictures with my IR camera and superimposed photos of the actual board manually. It's not a perfect result by any means but indicates the hot spots (white) pretty well. I wish I had one of these FLIR E8 cameras, they do this on the fly. Front with U25, I measured 108°C peak: 23587 Back side, here is another hotspot in the WiFi controller area but "only" around 60°C: 23584 Basically all voltage regulators (there are some more, I counted at least 10) are driven pretty hot. The U25 replacement definitely runs out of spec so I'll try to find out what is wrong there. Maybe it needs to be replaced by something more beefy that does not fit the SOT23-5 footprint. On the other hand, if more than 150mA are drawn, another component may wait to blow up next. Damn... I measured around U25 and found that it gets a stable input of 5V. The output however struggles to exceed 2.5V and rarely comes close to its designed 3.5V output. This can't be good. The recorded output waveform (~10seconds) shows a lot of noise. 23586 23588 I'll still have to do the same measurements with a fully intact Touch. Will be back soon. +-------------------------------------------------------------------+ |Filename: Touch startup voltage @ U25 output.png | |Download: http://forums.slimdevices.com/attachment.php?attachmentid=23588| +-------------------------------------------------------------------+ 1x Squezeebox Classic SB2 5x Squeezebox Classic SB3 (one waiting for repair) 7x Squeezebox Boom (two waiting for repair) 1x Transporter 1.5x Controller (one waiting for repair) 1.5x Touch (one waiting for repair) ------------------------------------------------------------------------ JoeMuc2009's Profile: http://forums.slimdevices.com/member.php?userid=23131 View this thread: http://forums.slimdevices.com/showthread.php?t=107453
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