Recent content by Mark_W

Hi all, thanks so much for your input. I double checked the voltage, reseated both rom chips as well as the swim chip, problem persisted. Swapped the motherboard into an SE chassis, same issue. Then I noticed something, I put a 47uf capacitor on C36 by mistake: Which should have been a 1uf...

Hello all, I picked up an SE SuperDrive last week and been busy restoring it. Cleaned the floppy drive and replaced the eject gear, recapped the analog/logic board and the power supply (it has an astec power supply and all capacitors tested good, but replaced them anyway), also dealt with...

Never used macsd before, did a quick google search and found this picture on their website: If the scsi connector is placed at the middle of the pcb then no it won't fit in the cc, cc's scsi cable is quite short and is connected to the motherboard edge connector directly so you can't replace...

Not sure if you seen this before but someone on github already reverse engineered the motorola ic and implemented it with discrete components: https://github.com/jonschultz/colorclassic_video_processor/ If you can order custom transformers then i guess there's no problem keeping the original...

Great work Arjen and congratulations on finally releasing the project. Took a quick look at it and noticed CP12 and CP15 are swapped, 100V capacitor should be on VE (+B, 60V) rail: Also some random thoughts: Can we use modular power supply instead of relying on original design? Most parts...

Regarding other common file types: .bin: macbinary encoded file, just use stuffit expander to extract it .hqx: hexa- or octal-encoded file, can't remember exactly, extract with stuffit expander .img, .dsk: floppy images (img could also be hdd or cd images, but you can tell by the size) and...

I use minivmac if the source file is a floppy image. It emulates a black and white 68k mac (plus iirc) so not the fastest emulator to work with, but on the plus side you can accelerate it and make file operations much faster. For sit files I use basilisk II or sheepshaver and enable the option...

Finally sorted everything out! This analog board really fought me till the very end. Long story short, after replacing all zener diodes and power resistors as suggested, the crt won't turn on at all. All voltages are present and logic board is booting, but no horizontal output at all. After...

Been working on this color classic on and off for a few days now, also spent some time reverse engineering the analog board, here are my findings: - Optocoupler near the smaller transformer (which outputs 60V, 24V and 8.3V and powers the CRT section) is for soft power only! It's NOT used for...

Ok it might seem ridiculous but I got it working! Bypassed the power supply section (desoldered transformer and switching mosfet) and connected 5v/12v/-12v capacitors to an atx psu, finally something showed up on screen. The image still has some stability issues and has hour glass distortion in...

Spent some time working on it this morning and noticed voltage on pin 6 drops to ~4v immediately after the power supply tries to start, then charges up slowly to 10v and next cycle continues. In theory the capacitor should be charged up by auxiliary winding through RP34 and DP15. They both...

Hello, I've been working on a color classics for a few nights now. Managed to fix the logic board after a recap, several trace repairs and a new DFAC-II sound chip. However, the analog board simply refuses to work. I've already recapped the analog board and replaced 2x TDA4605, 2xCNY17-3 and...

Btw this should be the correct position for t2 marker, to measure the end time of a complete cycle: Assume 50% duty cycle, the frequency should be 1/(t2-t1)=1/(800ns)=1.25MHz Or we can just use oscilloscope's default frequency measurement reading, it should take care of everything.

Grabbed my friend's se30 and removed rom, here's the result: Early revision with socketed cpu and pals. A2 is also 1.3mhz. And I think I know what's wring with the guide. Take a closer look at oscilloscope screenshot on pg 46, the frequency is calculated by 1/(t2-t1), but t2 is placed at...

I took another look at the repair guide: And on page 46 the scope shows square wave with 50% duty cycle, and its measurement is indeed 2.6MHz (pg 46): If ROM is installed, A2 will not show a perfect 50% duty cycle square wave, instead some irregular waveform as data is flowing on the bus (pg...