68kMLA Classic Interface

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Reverse Engineering the Color Classic AB
Posted by: rikerjoe on 2023-02-09 05:38:38
Answer is yes. Color Classic stereo mod instructions are available on the web, and I just finished gathering the needed parts to do the mod to my Mystic Color Classic as a project for #Marchintosh 2023.
Posted by: Cam on 2023-02-09 13:36:20
Here you go:
I haven't got my AB to work yet in stereo, but to be honest I haven't spent a lot of time troubleshooting it.
Posted by: rikerjoe on 2023-02-10 11:53:44
Here you go:
I haven't got my AB to work yet in stereo, but to be honest I haven't spent a lot of time troubleshooting it.
Yes, exactly the link I plan on using for my stereo mod.
Posted by: ironborn65 on 2023-02-17 06:53:00
In board revision C there is a connector (BC11 or BO11, I can not read it properly) that is not present in rev B.
1676644710250.png
at the back

1676644592293.png

as you can see, in rev B instead it's not present:
1676644578858.png
Following the trace it gets to the emitter of a transistor, whose collector is connected to the pin 1 of the optocoupler. The same trace goes to pin 5 of the connector that - given https://powercc.org/takky/ web page - it is the ADB Power Supply. The question it, what is supposed to be used for? A power-on LED?
Posted by: ironborn65 on 2023-02-17 07:04:56
another connector BV13 is present, on both board releases.
1676645649413.png
following the traces it gets to resistor RV46 and then to the output of the voltage regulator IP11.
I'm not able to bench test, I was wondering what's for.
Posted by: ironborn65 on 2023-02-20 05:27:53
1676898743987.png
View attachment 1676898845491.png

Component list is in https://github.com/pferronato/MacCCAB

Still work in progress
Posted by: ironborn65 on 2023-02-20 13:27:15
moving forward
endless work...

1676928053851.png1676928127305.png1676928177722.png1676928228251.png1676928389102.png
Posted by: pizzigri on 2023-05-27 09:24:41
I really hope you're continuing this. it's great work, and I believe that it actually could improve the quality of the CC AB, the only problem see is that there are at least three if not four revisions, and maybe it should be considered which revision is the most reliable so that the base project can be adapted to it.
An additional upgrade, once your project is completed, could be to isolate the HT/Video portion of the board and completely remove the LV part, instead relying on a ready built PSU of increased performance (i.e. Mean Well ultracompact and easily available units) "piggy backed" on the cleared part of the PCB to provide the standard voltages the LB needs to work, offloading burden to the rest of the components to both increase life and overall reliability of the board - and at the same time, simplify (re)construction.
Posted by: ironborn65 on 2023-05-28 01:23:31
correct @pizzigri , the model is 820-0360-B, I just added it to the README.

Replacing the PS is IMO already doable from the kicad file or from the dxf, but it's outside of my comfort zone due to lack of competences, I just did some donkey work
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