dwestbury Posted April 4, 2020 Report Share Posted April 4, 2020 (edited) Not sure what I did to completely mangle my Core 1 and/or SID 1 modules, but both MIDI comms to MIOS and audio are totally skewed now (UHG!).... Starting with the Audio Issue... SID modules #2 - 4 still sound perfectly fine (quick n dirty example below) https://drive.google.com/open?id=1FcfTqcUriYw4KaTXh1OSesTP9RLqs5_i ...But I've somehow managed to destroy the sound coming out of SID module 1?? https://drive.google.com/open?id=1tYVHFEG5-MbfYCJQZLcDfbC6LaOJ9Hk- Here's what I've done so far to try to fix this debacle... 1) Swapped SIDs chips around from other modules, but every SID sounds terrible when plugged into SID module 1 2) Swapped the filter caps (C1_SID1, C2_SID1, C21_SID1, C22_SID1) with brand new, tested 22nf metal film caps (I'm using all 8580R5 SIDs in my build) 3) Swapped the 10uf electrolytic caps that connect to J21 for audio out (C5_SID1 & C25_SID1) 4) Reflowed all joints under the Neutrik Audio out jack at J21 5) Reflowed all the solder joints on both SID sockets for SID1 Mod (U1_SID1 and U2_SID1) 6) Reflowed all the solder joins on the socket for for Core1 Mod (U1_Core1) 7) Burned a brand new PIC and swapped into Core1 ...Nothing has helped, so I'd really appreciate any insight... Edited May 6, 2020 by dwestbury Quote Link to comment Share on other sites More sharing options...
Hawkeye Posted April 4, 2020 Report Share Posted April 4, 2020 Are both left/right SID channels of engine 1 compromised? Did you measure if the voltages arriving at the SID chips of that engine are correct, especially the analog voltages? If those are good, it's just guesswork, but you could try to swap the output transistors north of those SIDs on your MB6582 baseboard? Have a good weekend and stay safe! Many greets, Peter Quote Link to comment Share on other sites More sharing options...
dwestbury Posted April 4, 2020 Author Report Share Posted April 4, 2020 (edited) 10 hours ago, Hawkeye said: Are both left/right SID channels of engine 1 compromised? Did you measure if the voltages arriving at the SID chips of that engine are correct, especially the analog voltages? If those are good, it's just guesswork, but you could try to swap the output transistors north of those SIDs on your MB6582 baseboard? Have a good weekend and stay safe! Many greets, Peter Hi again and thanks for pitching in! Yes, the sound from both SIDs is equally impacted from the SID1 mod. i can confirm that both the 9v and 5v levels are perfectly stable on both sockets and I've just swapped T1_SID and T21_SID for new BC547s, but still no luck unfortunately? I should also add that my newbie soldering is far from perfect, but I've been looking feverishly at every neighboring spot for cold joints, and making small touch-ups, etc. This one definitely has me puzzled... Edited April 4, 2020 by dwestbury Quote Link to comment Share on other sites More sharing options...
Noise-Generator Posted April 4, 2020 Report Share Posted April 4, 2020 I can remember I had a similar problem but unfortunately I forgot how I solved this. Quote Link to comment Share on other sites More sharing options...
dwestbury Posted April 4, 2020 Author Report Share Posted April 4, 2020 (edited) I've been able to play around with my 3 properly functioning Core / Sid modules, which has been great, but the issues with Mod 1 are driving me bananas... Adding to the process of elimination, I just swapped out the two 74HC595s in U3_SID1 and U4_SID1 and the Neutrik Audio jack in J21, but... I still haven't found the culprit... Now I'm left thinking that I may have nicked a trace under a socket somewhere or even torn a pad from all the desoldering? (Uhg...) 11 hours ago, Noise-Generator said: I can remember I had a similar problem but unfortunately I forgot how I solved this. Thanks @Noise-Generator - let me know If anything jars your memory... Edited April 5, 2020 by dwestbury Quote Link to comment Share on other sites More sharing options...
Hawkeye Posted April 5, 2020 Report Share Posted April 5, 2020 @dwestbury Hmm, it's a puzzle indeed - did you by chance install the overdrive/feedback potentiometer mods on all engines already? If so, could you disconnect them and test again? Good luck and many greets, Peter Quote Link to comment Share on other sites More sharing options...
Noise-Generator Posted April 5, 2020 Report Share Posted April 5, 2020 16 hours ago, dwestbury said: let me know If anything jars your memory... It seems to be output related but I'm some percent sure it also could be data-path and clock related. I would check and reflow the data lines from Core to SID and the quarz. (yellow marked area) Quote Link to comment Share on other sites More sharing options...
dwestbury Posted April 5, 2020 Author Report Share Posted April 5, 2020 (edited) On 4/5/2020 at 4:24 AM, Hawkeye said: @dwestbury Hmm, it's a puzzle indeed - did you by chance install the overdrive/feedback potentiometer mods on all engines already? If so, could you disconnect them and test again? Good luck and many greets, Peter Yes, I did try with and without my overdrive pots. I even shunted the audio-ins to ground to try and rule out any incoming noise as a possible root cause. Although, if the issue were actually noise or distortion, I would still expect the output volume level of SID 1 module to be similar to my other SID Modules? If you listen to my sound samples in the earlier post, you'll hear that Core 1 is both distorted and extremely quiet? Maybe this is a clue to the problem? On 4/5/2020 at 0:57 PM, Noise-Generator said: It seems to be output related but I'm some percent sure it also could be data-path and clock related. I would check and reflow the data lines from Core to SID and the quarz. That's a reasonable set of assumptions to pursue... I'll take a stab at reflowing the crystal, shift register sockets, relevant pin headers, etc. Basically everything in the data comms path... Edited April 7, 2020 by dwestbury Quote Link to comment Share on other sites More sharing options...
dwestbury Posted April 30, 2020 Author Report Share Posted April 30, 2020 (edited) I took a little break from this for a while to clear my head, but now I'm ready to shift back into diagnostics-mode... I decided to shift my mental attention towards the MIDI communications issue I've been having with core1, trying to talk to MIOS. I started out by comparing the voltages on core1, relative to my properly working cores (2-4) and here's what I see... I've been over all the points and joints countless times, so I'm really scratching my head with this one... Any guidance is appreciated... Edited May 6, 2020 by dwestbury Quote Link to comment Share on other sites More sharing options...
dwestbury Posted May 6, 2020 Author Report Share Posted May 6, 2020 (edited) Holy moly... My Core1 MIDI Issues are finally SOLVED... Turns out I had the wrong sized caps in C1_CORE1 and C2_CORE1 (embarrassing). This was impacting the oscillator frequency and effectively crippling core1. I have a big box of MLCC caps, which must shifted around in their compartments. That will teach me to examine those tiny little numbers better and test each component, before soldering! So, once I corrected the caps, all MIDI communication though MIOS are working again, wheeew... This old post from 2009 was immensely helpful, since it provided a solid technique that allowed me to leverage the oscillator frequency from core2 (working) into core1 (which was not working). I soldered some jumpers wires to the OSC1 and OSC2 pins on an extra 40-pin socket I had laying around and used them to bridge in the oscillators from core 2. Once the right frequency was fed into core1, it was able to communicate with MIOS properly. Once I knew the Oscillator was the issue, I was able to narrow my focus and figure out that I had the wrong caps in place (Doh!) So, now that my MIDI issue is resolved, I should be ready to tackle my SID audio issue next... ;-) More to come, Cheers... Edited May 6, 2020 by dwestbury Quote Link to comment Share on other sites More sharing options...
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