Recent content by mogs

I looked at the schematic after I sent my last message and saw the other 12V reg, I don't think I'd even noticed it before. My intention was to reduce complexity and replace it with modularity, your mods push this even further. Oh yeah, cheers 🍻, cool to see it get picked up.

Cool project, curious to know how you've connected stuff around the LM317? I think maybe in my final build I was injecting power into the lm317 input. I'd have to check the schematic but from memory it has soft start circuitry on the adj pin. I haven't played with my one since I ran out of...

I have one if these in my Plus. Also purchased from Kay Koba. It boots fine from the ROMinator when I hold the 'r' key down. Does boot this way? I haven't tried the Flash Tool yet, unfortunately I won't likely get an opportunity to test it any time soon but I'll report back here when I do if...

Thanks, it's taken till now for me to understand how those resistors are supposed to work. I have a pair of 1MB modules from a non working Classic to try. 4x1MB on the way. In the mean time I have the ROMinator and various SCSI gadgets to play with.... Oh, and 30+ years of filth to clean from...

So update, and success! I had a close look at the AB with the macro mode on my phone camera and could see where the solder pins to the connector might have been cracked. So I removed most of old solder, applied flux and re-soldered the pins, trying to ensure I was putting more heat in the pin...

I was going to start a new thread, but I think I'll just jump in here since I also have a mac plus with a black screen issue which may be related. My initial suggestions to your symptoms above. Chequerboard: remove the RAM and clean the contacts. Also, if both boards have exactly the same RAM...

@Trash80toHP_Mini Thanks, it was fun to get to that point, too bad I've run out of working classic 1,2 logic boards. Once the house is built I'll hopefully find time to play with these again. Been watching the logic board recreation threads with interest. I do like the SE/30 style AB form...

I get the same issue on my Q605 with some switchless DB15-DE15 cables I have. This is to a Samsung SyncMaster which seems to display pretty much anything the 605 can (with the exception of 512x384, which it does display, just not correctly). It's a shame since it would be nice not to need the...

So putting an ATX connector + audio amp circuitry on to the replacement logic board could mean the AB can be stripped right back to just a (modified) video circuit (+DC-DC boost to 31V for CRT) run from a molex. Then an off the shelf (Pico or SFF) ATX supply can be used either internally or...

The A/B can be considered as three separate systems (PSU + audio + video). I've managed to lobotomize the PSU components and hack in a Pico ATX PSU. https://68kmla.org/bb/index.php?threads/classic-classic-ii-atx-power-conversion.36679/ Was working nicely till the battery rot finally took out...

Should be fine, both use Atmega32U4 which is the magic sauce required for emulating USB devices.

The designers get to choose exactly how these two grounds are bonded, maintaining control over the flow of return currents at all frequencies. Otherwise you're leaving it to chance how high frequency return currents make their way back to the power supply. I've actually experienced this...

In answer to your question: RP2 is a NTC (negative temperature coefficient) resistor. This limits inrush current (due to relatively large values of capacitance CP1, CP13) when power is applied to the circuit. The cold resistance slows down the charging of those capacitors, when normal operating...

This looks pretty similar to what happened to my Classic II AB. Certainly the big MOSFET shorting is the most likely culprit. Although, in my case at least, it seems that the circuit can end up with such low impedance that a replacement fuse will draw very large currents before blowing taking...

So I followed up with this, and unfortunately it's not going to work. There is a local PCB fabrication place in town, and I knew they had an X-Ray machine for checking correct registration of multi-layer boards. I emailed them about the possibility of using it for imaging the internal layers...