ning wrote:KaiS wrote:I had to replace one already too, and believe me, that's no fun to do.
I would not suggest this to anybody with less than very, very good experience and equipment for SMD soldering.
curious how do you know which one failed in the first place?
I simply measured across the 6 individual 47 Ohms summing resistors.
Different voltage - found.
But, don't try to repair this by yourself.
The OPA1688's underneath thermal pad is soldered to the multilayer board, through-connected to the board's internal ground plane layer as heatsink.
Because of that, applying heat from above only will not work, before it gets hot enough to melt the solder paste the new chip is toast.
You would have to apply a lot of well dosed heat to that spot from underneath.
Too much heat and the board is toast.
Not enough, and the thermal pad does not connect, the chip will overheat when used.
An infrared thermometer is needed to check the success under working condition.
I want to stress again: without proper equipment and a lot of (very small type) SMD experience this cannot be done!
Some of you might have access to such, everybody else
-> RME service department.
A quick and dirty workaround is, to unlink the defective channel by removing it's 47 Ohm resistor.
Unsolder it, fix it on one side only, so it won't get lost.
This reduces the headphone amp's max output current by 1/6, to 83%, but makes the headphone amp usable again until there's time to order a proper chip replacement at RME's service department.