Shawn Posted May 11 Report Posted May 11 4 hours ago, dingding123 said: 17k smd resistors are quite hard to find. Would you recommend 20k or 15k ohm resistors? I didn`t check the schematic. However, the input resistors(Signal input) shouldn`t be a probably if you go with 15k or 20k. Quote
dingding123 Posted June 3 Report Posted June 3 Has anyone tried building this? Not sure if it's just me - after power on, the board overheats within a minute and then comes the magic smoke. PSU voltages are correct but output balance (i.e. L+ vs L-) goes from -2 to -60v quite quickly then suddenly normalises to around 4v). Pretty sure there are no shorts or issues with soldering on my board... Quote
kevin gilmore Posted June 3 Author Report Posted June 3 i am aware of the overheating issues. i have an assembled board coming to me to look into this. something clearly has changed from the original parts i used and there is some positive thermal runaway that did not happen with the prototype. there is a later version board now, 4 layers, still does not fix the problem. putting 12v zeners in series with the 1.1meg resistors may introduce enough negative thermal compensation. otherwise the bias needs to be trimmed a lot. hate the parts situation i do. Quote
kevin gilmore Posted June 3 Author Report Posted June 3 you are aware that you need a heatsink touching all the sot transistor. still with heatsink it typically can take about 5 minutes to reach high temps. Quote
Michelag Posted 2 hours ago Report Posted 2 hours ago On 8/7/2024 at 5:16 PM, kevin gilmore said: all three power supplies a total of $80.62 with shipping from china. fully regulated 12v to 18v input. i could not build these things for that price, no way. I was thinking, Kevin, are those bricks rechargeable? Does it need a battery management board? Quote
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