I come across a fair number of "defective" iPod "stereos" (countertop boxes into which an iPod is docked). Is there something intrinsically bad with these (besides being crappy consumer kit) that drives these failures?
(e.g., the docking and undocking of the iPod without, perhaps, adequate protection on the interconnect signals)
Well, if it is like many cordless phones, placing the handset onto the base while carrying a large static charge will scramble the base operation. On mine I need to unplug the wall wart from the base unit to restore operation. Unfortunately, the base always faults to the OFF- LINE state and puts a high level of receiver noise on the line and the only indication that it is not working is a). no calls received and b) picking up a wired phone greets you with the high level noise. I have repaired lots of equipment that has no factory installed ESD protection on the user interface and usually has a damaged interface chip or device. Most of these devices were industrial and the designer should have known better.
The biggest problem by far, is failure of the soldered joints on the actual dock connector. The connector has a metal surround with at least four tabs for soldering it to the board to provide mechanical strength to the assembly, and it is very typical to find that at least two of the tabs have no print provision for soldering them, or if there is, that the joint has just broken away. This allows the connector to flex, and the inevitable result is that the lead-free joints on the pins, which lack the ductility of leaded solder joints, give way. Symptoms can be anything from failure of the iPod to be recognised, no control of the iPod, no audio on one or both channels, or combinations of those problems either hard or intermittent. It is staggeringly difficult to repair these connections successfully no matter what soldering technique is used. This is due in no small part to the print itself, which invariably seems to be very thin and fragile, and often not well bonded to the pcb substrate. Some manufacturers eg Sony, supply a replacement board with the connector fitted, for some of their models. The problem is not restricted to any particular manufacturer. It seems to be a problem for them all, and is, I feel, just another consequence of replacing leaded solder technology which worked just fine, with lead-free, which doesn't ...
Most of these devices seem to have "sticky" (persistent) failures when I encounter them. I.e., it is not a transient issue associated with some action on my part.
For example, I have a unit, now, that runs well for "some amount of time" and then *appears* to keep running -- though any attempts to interact with it (the "dock") are ignored. E.g., withOUT an iPod docked into it, I can select the "RADIO" funtion, tune a station using the up/down buttons, adjust the volume, etc. The radio will play as expected. Some time later, an attempt to alter the volume or change the station will be totally ignored. Or, the device might power itself *off* unprovoked.
I.e., it is as if the processor in the thing has crashed and:
- left things "as is" (in the case where the radio keeps playing but buttons are ignored) or
- crashed and "reset" all the I/O to "off" in the process.
Behaviors on other devices have been similar. It is as if ESD has toasted something internally so that it only marginally works -- or works temporarily.
Most of these aren't worth the time to fix. I was just curious as to why so man of them -- different models, different manufacturers, etc. -- were exhibiting the same sorts of general failures.
So far, the problems I have seen are independant of the iPod. E.g., the box has problems "on its own" -- even without an iPod docked. I am assuming it is either a consequence of crappy components or related to ESD-type damage consequential to the exposure of live circuits to the user (no idea where all of those pins on the iPod connector are tied, internally).
(please see my reply to Neil re: a specific example)