Terin StockA few months ago I picked up an Apple IIc, which has been on my shelf since. I figured for #AprilApples I should clean it up and get it working again.
Hello fellow Apple II enthusiasts!
Hello fellow Apple II enthusiasts!
Now that everything is totally dry, I've put the Apple IIc back together. I'm really happy with how the handle turned out, less so by my skills protecting the "English" sticker on the spacebar.
More #AprilApples today, as the A2C DVI showed up. (As I'm not ready to tackle the monitor)
Good news: most of the Apple IIc seems to work.
Bad news: the floppy drive has a short.
Good news: most of the Apple IIc seems to work.
Bad news: the floppy drive has a short.
To make matters worse, this system is rocking ROM $FF, so I can't even boot from the Burger Disk. 🫠
AFAIK, I can't do anything with the SmartPort with this ROM and lack of a DOS.
AFAIK, I can't do anything with the SmartPort with this ROM and lack of a DOS.
As I'm building a 6502 homebrew computer, I have compatible EEPROMs, of course. Do I do the Apple Approved modification to cut traces?
A small bodge later (turns out I only had 28C256s) and we're back in business booting ProDOS from the Burger Disk!
However the system still freezes until I do Control-Closed Apple-Reset to get the ROM4X menu. I guess I need to fix the disk drive next.
However the system still freezes until I do Control-Closed Apple-Reset to get the ROM4X menu. I guess I need to fix the disk drive next.
Caps seem okay at first glance? I might have to see if Adrian has repaired one of these.
Looking at the pinout in the Apple IIc Technical Reference, it looks like the internal 51⁄4 drive has the same pinout as the Disk II drives. I have two Disk II drives, both have the same symptoms when connected to the IIc.
However, the internal 51⁄4″ Apple IIc drive works like a charm on the Apple II+!
Our fault is in another castle. Perhaps something is wrong with the DC-DC power supply card?
Our fault is in another castle. Perhaps something is wrong with the DC-DC power supply card?
Voltages from the DC-DC power supply all look very good on 5V, 12V and -12V while unloaded. UB13 also looks to be generating a good -5V (though it's not on the floppy ribbon cable).
Does anyone have an Apple IIc DC-DC power supply in working condition I can swap in to test?
Does anyone have an Apple IIc DC-DC power supply in working condition I can swap in to test?
With a drive connected and the keyboard unplugged (which I believe holds the CPU in reset) measured voltages are all good.
When the CPU is brought out of reset and it starts the floppy motor the voltages on all the rails drop.
When the CPU is brought out of reset and it starts the floppy motor the voltages on all the rails drop.
The DC-DC power supply board outputs -12V, 5V, and +12V. I only have two channels on my bench power supply so I can't just replace it. 🫠
I've removed all the old capacitors from the internal power supply. At least to my eyes, none looked to have failed.
Retiring capacitors, meet the new crew! As we all know, red makes the electrons go faster.
Unfortunately, the same symptoms in the Apple IIc when any floppy drive is connected. :(
I think next up is taking a look at the voltage regulators in the TO-220 package.
I think next up is taking a look at the voltage regulators in the TO-220 package.
I regret to inform everyone the issue has been resolved and the capacitor replacement was likely unnecessary.
I believed the label on the Apple IIc external power supply and I was current limiting the system with my bench power supply.
I believed the label on the Apple IIc external power supply and I was current limiting the system with my bench power supply.
Stuart Longland (VK4MSL)@terinjokes Just looking at that second photo, there's a pretty decent size transistor (2N6111) in a TO-220 package (and a couple of smaller TO-92 ones).
There are probably others, I wonder if those are okay? BJTs when subjected to high current can go into a thermal runaway mode which hastens their demise.
@stuartl I had them near the top of the list of suspects!
However, I instead washed my hands for dinner, this can wait until the weekend.
However, I instead washed my hands for dinner, this can wait until the weekend.