SynthAnthony Posted September 29, 2013 Report Share Posted September 29, 2013 (edited) Hi there, I still had a sammichSID kit lying around. Didn't finish it when it arrived, because couldn't do a proper testing (my cheapo multimeter was broken). Anyway, my Amprobe 37xr-a arrived, so the first thing I did is to test the assembly. It passed continuity test, but I don't get correct voltages from the voltage test - voltage readings are way too low. (I checked the power switch, it's ok - I also get 12.11V from the PSU). Personally, I have a feeling that it has something to do with my crappy soldering (I might have burned some components, although there is no visible damage). I use unregulated 12v 1250 mA PSU. Any help would be appreciated! Edited September 29, 2013 by SynthAnthony Quote Link to comment Share on other sites More sharing options...
nILS Posted September 30, 2013 Report Share Posted September 30, 2013 If you're already thinking that your soldering isn't quite up to par, then that's probably the issue ;-) Can you post some non-blurry, decent sized pictures of both sides of the PCB please? That might help us figure out what's wrong. Quote Link to comment Share on other sites More sharing options...
SynthAnthony Posted September 30, 2013 Author Report Share Posted September 30, 2013 If you're already thinking that your soldering isn't quite up to par, then that's probably the issue ;-) Can you post some non-blurry, decent sized pictures of both sides of the PCB please? That might help us figure out what's wrong. Thank you for a quick reply, I've uploaded the pics in high res (link: http://we.tl/QLBJ3Fqa5A ). This should be enough for a close inspection. You should notice it right away, but there is a bridge connection near one of the jacks (pad was destroyed, applied too much heat/pressure). Continuity test tells it's connected directly to the ground, not sure if it's supposed to be like that (even though I doubt audio path would cause problems in power supply voltages). Quote Link to comment Share on other sites More sharing options...
Imp Posted October 1, 2013 Report Share Posted October 1, 2013 You can attach the pics directly to your post. I'd start with cleaning the PCB. You have used way to much thermal compound. Next would be a continuity check between adjacent solderjoints. "Low voltages" sounds like you accidently connected something. Quote Link to comment Share on other sites More sharing options...
SynthAnthony Posted October 1, 2013 Author Report Share Posted October 1, 2013 You can attach the pics directly to your post. I'd start with cleaning the PCB. You have used way to much thermal compound. Next would be a continuity check between adjacent solderjoints. "Low voltages" sounds like you accidently connected something. About that - I already tried cleaning with isopropyl alcohol, but it only made it worse (residue went all over the pcb). What would be the best way to do so? Should I just remove the heatsink, clean it, and attach it again? And by "low voltages" I mean no voltages at all :no: Quote Link to comment Share on other sites More sharing options...
Imp Posted October 3, 2013 Report Share Posted October 3, 2013 Yes, remove the heatsink. Use a minimal amount of compound when reattaching it. Isopropyl is a good choice, use it with a Q-tip and remove all residue with toilet or kitchen paper as soon as it is solved. To check for shorts, you need to measure resistance between the pads of J1 and also between the each of the supply rails an ground (labeled +9v/Gnd and +5v/Gnd). Don't connect the powersupply yet. Quote Link to comment Share on other sites More sharing options...
SynthAnthony Posted October 19, 2013 Author Report Share Posted October 19, 2013 (edited) I removed the heat sinks and some components around it, removed all thermal compound - then temporarily surface mounted the two regulators, without heat sinks. Unfortunately, I forgot to put back the jumper near J20. Some magic smoke came out of one of the trimpots, when I connected the PSU. I'm afraid it's dead now... But, it seems like it solved the problem. Voltage readings on the base PCB are now correct! (I've put the jumper back). I'm a bit curious about what caused this problem - apparently it had something to do with the thermal compound, but why? (I used non-conductive compound). Edited October 19, 2013 by SynthAnthony Quote Link to comment Share on other sites More sharing options...
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