Moog The Source trouble

[tommygun]

Hi all, I'm hoping that I could get some help with troubleshooting Moog The Source. It appears that there may be some "Crazy Source" symptoms, but I'm unsure because the voltage regulator at U3 on the power supply board looks okay. I say that it "looks" okay because I haven't removed it for closer inspection. It seems that for some versions of this synth one can simply remove the regulator and clean with an eraser. Mine is different and I would have to desolder the regulator. I have the ability to solder and desolder, but I haven't come close to perfecting that yet so I'd like to avoid doing any of that if I can. I've included pics and videos below of the boards and issues.

There also appears to be at least one if not several modifications to this synth. Leads have been soldered DIRECTLY onto the legs of certain IC chips. Are these post manufacture mods?

Thanks for any help!
Tom

video #1 retriggering a new note above a note played not working
https://drive.google.com/file/d/1R8Oznj ... drive_link

video #2 another look at the retriggering issue in GLIDE mode
https://drive.google.com/file/d/1pakzhH ... drive_link

video #3 when in arp mode The Source does really weird stuff and is unplayable
https://drive.google.com/file/d/147x0DG ... drive_link

video #4 another look at the arp mode
https://drive.google.com/file/d/1wttT90 ... drive_link



Top of power supply board
https://drive.google.com/file/d/1-Fk45q ... drive_link

Close up of voltage regulator at U3
https://drive.google.com/file/d/1sdy7aX ... drive_link

Bottom of power supply board
https://drive.google.com/file/d/1QxHl3R ... drive_link

Zoomed in bottom of power supply board... strange scratch all the way across trace involving voltage regulator at U3
https://drive.google.com/file/d/1AfJgzv ... drive_link

Is S71 a mod to The Source?
https://drive.google.com/file/d/1WBo_7q ... drive_link

Full boards view
https://drive.google.com/file/d/1jotr1p ... drive_link

Board #1 Closeup
https://drive.google.com/file/d/1e22dUb ... drive_link

Board #2 Closeup
https://drive.google.com/file/d/1ijbXLP ... drive_link

[analogmonster]

And what is the trouble now?

...
There also appears to be at least one if not several modifications to this synth. Leads have been soldered DIRECTLY onto the legs of certain IC chips. Are these post manufacture mods?
...

Probably.

[tommygun]

Thank you for responding though I'm not sure what is unclear. All of the problems in the videos are the trouble....

[analogmonster]

No, I mean when you use the instrument, are there any stability issues, drifts, scratches, malfunctions etc.?

[tommygun]

I'm sorry! I didn't realize that I forgot to include links to the videos demonstrating the problems. They are now in my original post.

[analogmonster]

Ad 1,2: Some synths have lower note priorization. Are you sure that yours should have higher note priorization implemented / activated?

Ad 3,4: Provided that all keys work correctly in monophonic mode: Seems that keyboard scanning for arpeggio is not possible. There could be corrosions on the address or data bus. To be sure all CPU board IC contacts should be cleaned / resoldered, but that is a lot of work. If you do that, start with the EPROM, to be sure that all program banks are available.

[tommygun]

Thank you soooo much for your responses. I'm a little embarrassed by what I'm about to share, but it's all about learning more about synths.

When you mentioned "note priority" I thought that I should check the owner's manual and sure enough, The Source prioritizes the lower note. I don't really understand why this would be the case. I assume prioritizing the last note pressed would be best.

After discovering this I decided to look up how the arpeggio mode works. Turns out it's totally different than I expected and it works as it should. Well gosh darn. It's not at all like how I expected it would work. I expected it to function like my Juno-60.

Finally, the board modifications, I discovered from the service manual, were an official modification so that The Source could work with drum machines of it's era. I verified several of the modifications described in the service manual including the wire soldered directly to the IC chip that I mentioned.

With some cleaning of the key contacts everything seems to be working as it should. Thanks again for your time!

Tom

[analogmonster]

Cool