Sunday, September 26, 2010

Apple IIgs 1mb memory expansion to 4mb conversion

In the past a post to comp.sys.apple2 referred to this site: which documents how someone converted a common 1mb apple memory expansion card to 4mb using 30 pin simms. Recently, I also found another guy who did the same thing but not using 8/9 chip simms .

Since I do not have any 30 pin simms lying around I did not undertake this conversion. Recently I found some simms on ebay for under $10. I decided that maybe it's time to try this out.

This is how a card would look before the conversion:

The directions said to remove all the dram chips, sockets and capcacitors:
Here are the simms we're going to use:
We use double sided tape to attach the simms:
Then follow the schematic diagram. This is how it looks after the address lines are hooked up:
After several hours it's finally finished:

Lets plug it in:

Running the memory testing program from:

I'm leaving this running overnight to see if it produces any errors.

Friday, July 2, 2010

Apple IIc plus 240V modification revisited

In the previous modification I essentially followed Jorge's mod:
and adapted it with locally available parts.

This has one big drawback. It generates a lot of heat. It is also very inefficient. The voltage is dropped down by letting it go as heat. With the case closed, it may (I did not want to try) be possible to reach a temperature that can warp, deform, or quickly yellow the area of the case near the power supply.

I thought about modifying the switching power supply the "proper" way, but without knowing the actual design of the original supply, plus my limited knowledge of switching power supplies, I thought this may not be the way for me to go.

James Littlejohn have made a lot of adaptors for ATX power supplies for use with Apple II's. One of the items he has is the LittlePower IIc+. This handy device, plus a small enough ATX supply should be enough to run the IIc+ with no problems.

After waiting a few weeks for the USPS to deliver my mail, I finally got all the parts I need. Earlier today, I opened up the IIc+ to to a quick test:
After getting it to work, I proceeded to taking the power supply and the power brick apart:

As you can see the power brick is way smaller than the original power supply. This will fit nicely into the original metal shell, and still have room for the LittlePower IIc+ and the picopsu.

Now it's time to wire the picopsu directly to the power brick. Note that I have kept the shell and all the parts in case I want to put it back together. Or in case I decide I want to turn the IIc+ into a portable device with battery, etc built in. There is a grounding board at the bottom of the unit, it wasn't too hard to desolder this:
This is the actual board of the power brick. The AC goes into the 3 big pads near the right side:
Unfortunately for me, the LittlePower IIc+ doesn't fit into the metal shell in its intended location over the hole. It must have been expected that you will be removing the internal power supply to use this device. If I remove the power supply, there will be nothing to hold the switch and the IEC connector at the back. I thought that maybe I could extend the connector with some wires:
Ok looking good.
After putting electrical tape on the parts that can potentially touch the case, including the ATX pins, I am now able to close the case: (if you look carefully you can actually see the green LED of the power brick when the unit is on)

Finally I can close the whole case:

Run a short Applesoft program:

I have left both apple keys held down to run a continous self test. So far it's been 3 hours and I don't feel too much heat (next to none) out of the power supply. I may or may not revisit this yet again. I might decide to power the unit with batteries. There is still room on both sides of the 3.5" floppy drive for other things so maybe I may be able to leave the brick internal.

Friday, June 4, 2010

iPod touch repair

I recently came into possession of 2 ipod touch units. One is a 32Gb 2nd gen, the other an 8Gb 3rd gen (which is essentially same as the 2nd gen).

The first unit had a snapped ribbon cable. The previous owner attempted to replace the touch screen and ended up breaking the cable. To make things worse, the screen looks like it is "white on black". The midframe (plastic stuff) was also missing a big chunk of.

Off to ebay to get:
2nd gen touch screen
mid frame
2nd gen LCD

In the meantime I had a look at the 8Gb 3rd gen unit. Looks like this unit has never been opened, and the only thing really wrong with it is the bent pins in the dock connector. While I waited for the parts to arrive, I thought I'd just take the parts from this unit and get the 32Gb working. I transferred the LCD first, then the touch screen + midframe. After using a lens blower to blow away all the dust and brushing a bit with a lens brush, I closed up the unit. This unit is working very well, but it has a very short battery life. I just then added a battery to the list of parts. I didn't get a chance to take pictures of this unit, but since I moved all the broken parts to the other unit, I will take pictures when I do that.

The 2nd unit is a 8Gb 3rd gen unit (actually a 2nd gen unit).
After removing the LCD, this is what's inside

And after removing the metal shield (desoldered the 2 blobs on both sides and pried up the metal clips) we see the dock connector's completely bent pins

At this point, I was thinking of what to do with it. I could desolder the whole connector and replace it with one from one of my old broken ipod minis. But this means using a SMD rework station to heat the whole area potentially blowing off some of the nearby (tiny) components. I first checked if it was possible to straighten the pins. Using a small screwdriver I carefully "combed" the pins. This is the result:

Using an external USB power supply I plugged it in. No smoke. Seems to be a good sign. I went ahead and hooked up the LCD from the other unit:

That is what I meant when I said the colours were reversed. Everything looked like that, including the apple logo on boot up.

Well, having seen that the board is still working and that the dock connector is somewhat usable, I went ahead and tested it on my computer. It was detected by itunes and wanted to erase the contents. That's a good sign, it means that the USB pins also work. After "combing" the pins some more to get it as straight as I could, I soldered the shield back in place.

Then it's time to unpack the new LCD screen:

After installing the new screen:

After that I had to double sided tape the new frame (which arrived in 3 pieces) to the new touch screen and lock it on.

12-06-10 Update: My batteries for the first unit just arrived (in antistatic bag):

Here it is taken out:
After taking out the old battery:
A test fit:
Applied the solder:
Test with "bad" LCD. I have been using the "reversed colour" LCD to test. I try to keep the working LCD in a dust free environment.

After installing the original LCD and touch screen:

Saturday, May 22, 2010

Apple IIe TTL RGB to Commodore 1084s monitor

I have finally finished constructing my cable. Parts have just been sitting there waiting to be put together for a long time but I was too lazy to put them together.

So here is both sides of the cable:

This is how the whole setup looks like (Still no disk drives for now)

When I got this IIe, the Delete key was missing, So I looked for a temporary key to put in its place:

Here's the Startup screen:

Here's some 80 column text

And finally some low res graphics:

Update. After I tried to run some game, I realized that some of the colours look "not-quite-right". Output of the same program on Sweet 16 shows this:
I found from this post that the card actually outputs xrgb. I would have to think of how to resolve this issue... more updates later.