[djwkjp]

hello. i recently finished my pimeta and i am having a problem. i tried using the search function, but i couldnt find any answers to my problem. so here it goes. first of all, my amp has 2 buffers per channel, including ground. i havent cased it up yet, but i make sure to isolate the output jack from everything else when i am using it. i measured about 5 mV of offset at each output and i am using 2 9 volt alkalines as my power source. so, my problem is when i am listening to the amp, after a certain amount of time, the sound cuts out and i hear staic, which builds in volume and then everything cuts out and i dont even hear hissing in the background. so i switch it off and turn it back on, and the amount of time it will play before shutting down again seems to correspond to how long i had it on. if i shut it off for a few seconds, it will play for a few seconds then nothing. i have tried both ad8610/8620 and poa 134/2134 and it does it with both. the opamps dont feel hot, and neither does the tle. i didnt check the power rails to the opamps, but i will do that soon. is my amp occilating? i dont know exactly what symptoms of occilation look like, so i dont know.
any and all help will be appreciated.
thanks
dan

 

[djwkjp]

ok... i just checked the rails on my amp and each opamp is getting +/- 6 V.

 

[tangent]

That sounds like a grounding problem.

- Clean the flux from the board.

- Remove the amp from the case, if it's a metal case. Let the jacks flop about on the ends of their hookup wires. If that fixes it, one of the jacks is grounded incorrectly.

- Remove the input and output jacks and use alligator clips to connect them to your input and headphone cables. If that fixes it, one of the jacks is probably damaged, such as from being overheated by the iron.

The symptom happens because an amp or buffer is going into current limiting and is shutting down. I'm guessing on the grounding problem, since an inadvertent high-impedance short to ground is the most likely cause.