So brief history. I have been recently into the synth repair world for under a year diy - modding- etc but collecting for ever. Friend calls me up with the normal battery damaged p6 among other things.. It has a long history with various issues that i think all summed up into its current state. So the battery damage we got lucky and it only affected a small amount of trace. The traces cleaned up did not need jumpering and all tested. ICs were healthy as well as a few components around the area (on a side note i had a poly 61 recently and it was about as bad as it gets so i have gotten to see the two extremes). However the other main issues were..
1. At some point something very heavy fell on the case hard enough to make a large dent across the metal panel and bend a few pots. Now this apparently didnt affect it at first but i think it did over time and i will come to that later.
2, The owner accidentally turned on phantom power to the synth. This was when it primarily stopped working properly with a large hum and incredibly reduced audio output. Once again i will return to this point...
Below is a short list of what i was able to find and repair through this endeavor.
Battery area was cleaned tested and replaced. The synth functions and generates sound with all switches and buttons and pots,voices working. Tape back up and patch restoration worked.
PSU was tested and trimmed to spec.
Keys were cleaned restored 5 keys were not working, now all keys work.
All tac switches were replaced with NOS.
Now the audio issues all resided on the KLM 368 board. We had the brief opportunity to purchase one and did not move fast enough so i began to inspect and repair it. As i first pulled it out i noticed some small areas of oxidation perhaps from the battery and cleaned and tested traces and they were fine. Im assuming due to the heavy thing falling on it, there was a small section of the PCB corner next to one of the screw mounts that had broken off however it doesn't seem to affect the board and was small and not near the traces, however it was an omen i think of what was to come. I'm assuming due to the 48v, the quad opamps were dead along with many of the duals and OTAs on the board. There were a few bad caps, all were bad components were replaced and low and behold the synth was making healthy albeit loud sound This was when i could test the ARP, EG, and other functions. Then after 5 or so minutes a loud POP and it would dive off again into a noisy crackling thing with the sound present but incredibly reduced, or sometimes just not there. Also you could literally tap on lightly move the synth and it would come or go with a loud pop each time. So after calling around and getting some tips (some i read in here) i pulled the board for a closer inspection i noticed that the CN at the top of the board were sort of loose not in the connection sense but as in loose on the board. i put the board back in and with the synth on i probed around with a non metallic probe just pressing on portions of the board and also ice spray with some components. This was after the sound dropped out and as i probed in areas around the connection it would crackle loudly and come back to life.. sit there and POP die again. BTW there was +15/-15 tested coming into the board and signal as well was coming in fine to the board. So something more mechanically wrong it seemed. So after a kind soul sat down with me in conversation about what i could have missed in problem solving. He said pull it again and really look at it and inspect it see if it has cracks etc.. So i pulled it and tried to see why the CNs were loose i was about to desolder the Power CN and that was when i saw that the solder pads had come up form the board. At this point I am thinking that ( and this is where that heavy thing comes into play) when the heavy thing fell on it it could have literally pushed the components into the board so hard causing this issue. the pads on the other CNs look okay but until there is power to this board i wont know again.
So Replacing the pads is a total PITA however with all the attention to the 367s it seems the 368s to find are rarer than hens teeth, many places i have written do not have replacements and haven't seen them in a while. Is there anyone out there with a replacement 368 . Or can someone point me in the direction of a solid pad repair kit? For all the soldering and desoldering i have done i havent come across the lifted pads. It was bound to happen i know its common but i dont think i was ready for it.. trying everything to test and check components and ICs and then it ends up something like this..
All responses are welcome
--HIll
PS im in Europe.