Recent content by dhoelzer

I know I can purchase the a2heaven ram expansion for $70 when instock. However, looking at the schematics of the IIc's expansion port and reading the disassembly of the ROM code that deals with it, it seems that this is just RAM connected to slot #4 with ROM code to let you treat it like a...

Nope, serial issue not resolved. Only 7 bits in or out.

Nope. This is a ROM3 originally, but I have a ROM4 in it. I have to try the serial ports with the power issue addressed and see if there's a change.

My own question answered... I think all of this was caused by an underpowered external PSU. I switched to a 4 amp 20 volt external and all seems well.

Another question... Reviewing the schematics that AppleFritter has for the IIc, I'm noticing that sheet 5 shows that the connectors from the external PSU that I keep reading are not connected to anything, actually are... They run to the 1488 and 1489 serial lines. Am I crazy to think that this...

Yes, Verault. That's documented above in the post from 3:36.

And things have gotten worse.. It will now sometimes do it with only the internal floppy installed. It does seem like it's the internal switching PSU that's cutting out because of the fault, whatever it is. I'm thinking about wiring a bench supply in to the system to see if I can follow the...

Oh, interesting... With *anything* connected to the smartport, it can happen. It just happened with only a floppyemu connected, and that draws very little. To sum up: * It only happens with an internal 5.25 connected * Any 5.25 drive internally will cause it * With the internal drive...

No problem when the internal disk is disconnected. Yes, this only happens with the external unidisk connected.. but without the internal drive, I can connect the unidisk and another 5.25 behind it with no problem. I haven't tried measuring voltages when it does this, but that's a super idea...

Well, I dismantled the external 5.25 unidisk. It took some doing, but I wired it in... The system behaves *identically*. As soon as the internal drive tries to spin, "powerdown" like overcurrent protection. I'm remembering back now that I actually tried a different internal PSU in this iic a...

Yes, the voltages all look fine. The system operates completely fine most of the time. It's only sometimes that it acts in this way. I do have an external 5.25.. I've never had it apart and it's just stored. I'll open it up and see if that drive can fit in the chassis and if the behavior is...

Mm.. Pulled them all, tested (all good, one marginal) and replaced. Still has the same issue, regardless of external PSU. Any other thoughts?

Ok, I'll give that a shot. Thanks Timo. I've already swapped the external supply.

I have a IIc... Works fine without the unidisk connected. Normally works fine with the unidisk connected. However, sometimes, when I power on, it will beep and begin to spin the drive and then "power off."... It looks like over-current protection, but I need some guidance about where I should...

I did look at that... it's expensive to build...